Publications

Lanese, I & Devitt, S 2016, Preface.

Tomamichel, M 2016, Quantum Information Processing with Finite Resources - Mathematical Foundations, Springer, Cham, Switzerland.
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One of the predominant challenges when engineering future quantum information processors is that large quantum systems are notoriously hard to maintain and control accurately. It is therefore of immediate practical relevance to investigate quantum information processing with limited physical resources, for example to ask: How well can we perform information processing tasks if we only have access to a small quantum device? Can we beat fundamental limits imposed on information processing with classical resources? This book will introduce the reader to the mathematical framework required to answer such questions. A strong emphasis is given to information measures that are essential for the study of devices of finite size, including R\'enyi entropies and smooth entropies. The presentation is self-contained and includes rigorous and concise proofs of the most important properties of these measures. The first chapters will introduce the formalism of quantum mechanics, with particular emphasis on norms and metrics for quantum states. This is necessary to explore quantum generalizations of R\'enyi divergence and conditional entropy, information measures that lie at the core of information theory. The smooth entropy framework is discussed next and provides a natural means to lift many arguments from information theory to the quantum setting. Finally selected applications of the theory to statistics and cryptography are discussed.

Ying, M 2016, Foundations of Quantum Programming, Morgan Kaufmann.
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Devitt, SJ, Stephens, AM, Munro, WJ & Nemoto, K 2016, 'Analysis of an atom-optical architecture for quantum computation' in Lecture Notes in Physics, pp. 407-437.
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Ying, M 2016, 'Analysis of quantum programs' in Foundations of Quantum Programming, Elsevier, pp. 149-207.
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Ying, M 2016, 'Logic for quantum programs' in Foundations of Quantum Programming, Elsevier, pp. 103-148.
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Ying, M 2016, 'Preliminaries' in Foundations of Quantum Programming, Elsevier, pp. 11-58.
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Ying, M 2016, 'Prospects' in Foundations of Quantum Programming, Elsevier, pp. 327-336.
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Ying, M 2016, 'Quantum case statements' in Foundations of Quantum Programming, Elsevier, pp. 211-271.
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Ying, M 2016, 'Quantum recursion' in Foundations of Quantum Programming, Elsevier, pp. 273-324.
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Ying, M 2016, 'Syntax and semantics of quantum programs' in Foundations of Quantum Programming, Elsevier, pp. 61-102.
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Asaad, S, Dickel, C, Langford, NK, Poletto, S, Bruno, A, Rol, MA, Deurloo, D & DiCarlo, L 2016, 'Independent, extensible control of same-frequency superconducting qubits by selective broadcasting', NPJ QUANTUM INFORMATION, vol. 2.
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Berta, M & Tomamichel, M 2016, 'The Fidelity of Recovery Is Multiplicative', IEEE TRANSACTIONS ON INFORMATION THEORY, vol. 62, no. 4, pp. 1758-1763.
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Bremner, MJ, Montanaro, A & Shepherd, DJ 2016, 'Average-Case Complexity Versus Approximate Simulation of Commuting Quantum Computations', PHYSICAL REVIEW LETTERS, vol. 117, no. 8.
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Chan, B, Guan, H, Hou, L, Jo, J, Blumenstein, M & Wang, J 2016, 'Defining a conceptual framework for the integration of modelling and advanced imaging for improving the reliability and efficiency of bridge assessments', Journal of Civil Structural Health Monitoring, vol. 6, no. 4, pp. 703-714.
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© 2016, Springer-Verlag Berlin Heidelberg. Current bridge inspection practices are typically predicated upon manual paper-based data collection methods, which significantly limit the ability to transfer knowledge gained throughout the lifecycle of the asset, to benefit the assessment of the inspector or engineer. This study aims to overcome the limitations of current practices and proposes a conceptual framework to improve the reliability and efficiency of current bridge asset management practices through the integration of Building Information Modeling (BIM) and advanced computing and imaging technologies. As a tool for bridge inspections, BIM offers significant potential when integrated with laser scanning and keypoint-based texture recognition, which allows for the detection of such defects as cracking, corrosion or settlement in bridge components. In recent years, the construction industry has seen an increased use of BIM technology on-site to aid the construction process. However, the applications of it are deficient through the asset management phases of a project. Given the ability of BIM to house all component specific information gathered from the construction, inspection and maintenance phases, BIM is envisioned to allow emphasis to be placed on retrieving the relevant information throughout the project lifecycle, ultimately enabling engineers and bridge inspectors to make more informed decisions about the current condition of the structure. Using BIM as the focal point for information collection throughout the project lifecycle, findings from advanced imaging and data processing are proposed to be stored within the model for recall at future bridge assessments.

Chapman, RJ, Ferrie, C & Peruzzo, A 2016, 'Experimental Demonstration of Self-Guided Quantum Tomography', PHYSICAL REVIEW LETTERS, vol. 117, no. 4.
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Chen, J, Ji, Z, Yu, N & Zeng, B 2016, 'Detecting consistency of overlapping quantum marginals by separability', PHYSICAL REVIEW A, vol. 93, no. 3.
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Chen, J-Y, Ji, Z, Liu, Z-X, Shen, Y & Zeng, B 2016, 'Geometry of reduced density matrices for symmetry-protected topological phases', PHYSICAL REVIEW A, vol. 93, no. 1.
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Chen, J-Y, Ji, Z, Yu, N & Zeng, B 2016, 'Entanglement depth for symmetric states', PHYSICAL REVIEW A, vol. 94, no. 4.
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Cheng, H-C & Hsieh, M-H 2016, 'Characterizations of matrix and operator-valued Phi-entropies, and operator Efron-Stein inequalities', PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, vol. 472, no. 2187.
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Cheng, H-C & Hsieh, M-H 2016, 'Concavity of the Auxiliary Function for Classical-Quantum Channels', IEEE TRANSACTIONS ON INFORMATION THEORY, vol. 62, no. 10, pp. 5960-5965.
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Cheng, H-C, Hsieh, M-H & Yeh, P-C 2016, 'THE LEARNABILITY OF UNKNOWN QUANTUM MEASUREMENTS', QUANTUM INFORMATION & COMPUTATION, vol. 16, no. 7-8, pp. 615-656.
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Chitambar, E & Hsieh, M-H 2016, 'Relating the Resource Theories of Entanglement and Quantum Coherence', PHYSICAL REVIEW LETTERS, vol. 117, no. 2.
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Chitambar, E, Hsieh, M-H & Winter, A 2016, 'The Private and Public Correlation Cost of Three Random Variables With Collaboration', IEEE TRANSACTIONS ON INFORMATION THEORY, vol. 62, no. 4, pp. 2034-2043.
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Das, A, Ferrer, MA, Pal, U, Pal, S, Diaz, M & Blumenstein, M 2016, 'Multi-script versus single-script scenarios in automatic off-line signature verification', IET BIOMETRICS, vol. 5, no. 4, pp. 305-313.
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Das, A, Pal, U, Ferrer, MA & Blumenstein, M 2016, 'A framework for liveness detection for direct attacks in the visible spectrum for multimodal ocular biometrics', Pattern Recognition Letters, vol. 82, no. 2, pp. 232-241.
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In this research a new framework for software-based liveness detection for direct attacks in multimodal ocular biometrics across the visible spectrum is proposed. The framework aims to develop a more realistic method for liveness detection compared to previous frameworks proposed in the literature. To fulfil the above highlighted aims in this framework, intra-class level (i.e. user level) liveness detection is introduced. To detect liveness, a new set of image quality-based features is proposed for multimodal ocular biometrics in the visible spectrum. A variety of transformed domain (focus related) aspect and contrast-related quality features are employed to design the framework. Furthermore a new database is developed for liveness detection of multimodal ocular biometrics, which has the prominent presence of multimodal ocular traits (both sclera and iris). Moreover this database is comprised of a larger variety of fake images; those were prepared by employing versatile forging techniques which can be exhibited by imposters. Therefore the proposed schema has dealt with versatile categories of spoofing methods, which were not considered previously in the literature. The database contains a set of 500 fake and 500 genuine eye images acquired from 50 different eyes. An appreciable liveness detection result is achieved in the experiments. Furthermore, the experimental results conclude that this new framework is more efficient and competitive when compared to previous liveness detection schemes.

Datta, N, Hsieh, M-H & Oppenheim, J 2016, 'An upper bound on the second order asymptotic expansion for the quantum communication cost of state redistribution', JOURNAL OF MATHEMATICAL PHYSICS, vol. 57, no. 5.
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Datta, N, Tomamichel, M & Wilde, MM 2016, 'On the second-order asymptotics for entanglement-assisted communication', QUANTUM INFORMATION PROCESSING, vol. 15, no. 6, pp. 2569-2591.
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Devitt, SJ 2016, 'Performing quantum computing experiments in the cloud', Physical Review A, vol. 94, no. 3.
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© 2016 American Physical Society. Quantum computing technology has reached a second renaissance in the past five years. Increased interest from both the private and public sector combined with extraordinary theoretical and experimental progress has solidified this technology as a major advancement in the 21st century. As anticipated my many, some of the first realizations of quantum computing technology has occured over the cloud, with users logging onto dedicated hardware over the classical internet. Recently, IBM has released the Quantum Experience, which allows users to access a five-qubit quantum processor. In this paper we take advantage of this online availability of actual quantum hardware and present four quantum information experiments. We utilize the IBM chip to realize protocols in quantum error correction, quantum arithmetic, quantum graph theory, and fault-tolerant quantum computation by accessing the device remotely through the cloud. While the results are subject to significant noise, the correct results are returned from the chip. This demonstrates the power of experimental groups opening up their technology to a wider audience and will hopefully allow for the next stage of development in quantum information technology.

Devitt, SJ 2016, 'Programming quantum computers using 3-D puzzles, coffee cups, and doughnuts', XRDS: Crossroads, The ACM Magazine for Students, vol. 23, no. 1, pp. 45-50.
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Devitt, SJ, Greentree, AD, Stephens, AM & Van Meter, R 2016, 'High-speed quantum networking by ship', Scientific Reports, vol. 6.
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© The Author(s) 2016. Networked entanglement is an essential component for a plethora of quantum computation and communication protocols. Direct transmission of quantum signals over long distances is prevented by fibre attenuation and the no-cloning theorem, motivating the development of quantum repeaters, designed to purify entanglement, extending its range. Quantum repeaters have been demonstrated over short distances, but error-corrected, global repeater networks with high bandwidth require new technology. Here we show that error corrected quantum memories installed in cargo containers and carried by ship can provide a exible connection between local networks, enabling low-latency, high-fidelity quantum communication across global distances at higher bandwidths than previously proposed. With demonstrations of technology with sufficient fidelity to enable topological error-correction, implementation of the quantum memories is within reach, and bandwidth increases with improvements in fabrication. Our approach to quantum networking avoids technological restrictions of repeater deployment, providing an alternate path to a worldwide Quantum Internet.

Duan, R & Winter, A 2016, 'No-Signalling Assisted Zero-Error Capacity of Quantum Channels and an Information Theoretic Interpretation of the Lovasz Number', IEEE Transactions on Information Theory, vol. 62, no. 2, pp. 891-914.
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We study the one-shot zero-error classical capacity of a quantum channel assisted by quantum no-signalling correlations, and the reverse problem of exact simulation of a prescribed channel by a noiseless classical one. Quantum no-signalling correlations are viewed as two-input and two-output completely positive and trace preserving maps with linear constraints enforcing that the device cannot signal. Both problems lead to simple semidefinite programmes (SDPs) that depend only on the Kraus operator space of the channel. In particular, we show that the zero-error classical simulation cost is precisely the conditional min-entropy of the Choi-Jamiolkowski matrix of the given channel. The zero-error classical capacity is given by a similar-looking but different SDP; the asymptotic zero-error classical capacity is the regularization of this SDP, and in general we do not know of any simple form. Interestingly however, for the class of classical-quantum channels, we show that the asymptotic capacity is given by a much simpler SDP, which coincides with a semidefinite generalization of the fractional packing number suggested earlier by Aram Harrow. This finally results in an operational interpretation of the celebrated Lovasz $\vartheta$ function of a graph as the zero-error classical capacity of the graph assisted by quantum no-signalling correlations, the first information theoretic interpretation of the Lovasz number.

Duan, R, Severini, S & Winter, A 2016, 'On zero-error communication via quantum channels in the presence of noiseless feedback', IEEE Transactions on Information Theory, vol. 62, no. 9, pp. 5260-5277.
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We initiate the study of zero-error communication via quantum channels when the receiver and sender have at their disposal a noiseless feedback channel of unlimited quantum capacity, generalizing Shannon's zero-error communication theory with instantaneous feedback. We first show that this capacity is a function only of the linear span of Choi-Kraus operators of the channel, which generalizes the bipartite equivocation graph of a classical channel, and which we dub "non-commutative bipartite graph". Then we go on to show that the feedback-assisted capacity is non-zero (with constant activating noiseless communication) if and only if the non-commutative bipartite graph is non-trivial, and give a number of equivalent characterizations. This result involves a far-reaching extension of the "conclusive exclusion" of quantum states [Pusey/Barrett/Rudolph, Nature Phys. 8:475-478]. We then present an upper bound on the feedback-assisted zero-error capacity, motivated by a conjecture originally made by Shannon and proved later by Ahlswede. We demonstrate this bound to have many good properties, including being additive and given by a minimax formula. We also prove that this quantity is the entanglement-assisted capacity against an adversarially chosen channel from the set of all channels with the same Choi-Kraus span, which can also be interpreted as the feedback-assisted unambiguous capacity. The proof relies on a generalization of the "Postselection Lemma" [Christandl/Koenig/Renner, PRL 102:020504] that allows to reflect additional constraints, and which we believe to be of independent interest. We illustrate our ideas with a number of examples, including classical-quantum channels and Weyl diagonal channels, and close with an extensive discussion of open questions.

Ferrie, C & Blume-Kohout, R 2016, 'Minimax Quantum Tomography: Estimators and Relative Entropy Bounds', PHYSICAL REVIEW LETTERS, vol. 116, no. 9.
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Hayashi, M & Tomamichel, M 2016, 'Correlation detection and an operational interpretation of the Renyi mutual information', JOURNAL OF MATHEMATICAL PHYSICS, vol. 57, no. 10.
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Hsieh, M-H & Watanabe, S 2016, 'Channel Simulation and Coded Source Compression', IEEE TRANSACTIONS ON INFORMATION THEORY, vol. 62, no. 11, pp. 6609-6619.
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Jerger, M, Reshitnyk, Y, Oppliger, M, Potocnik, A, Mondal, M, Wallraff, A, Goodenough, K, Wehner, S, Juliusson, K, Langford, NK & Fedorov, A 2016, 'Contextuality without nonlocality in a superconducting quantum system', NATURE COMMUNICATIONS, vol. 7.
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Khare, V, Shivakumara, P, Raveendran, P & Blumenstein, M 2016, 'A blind deconvolution model for scene text detection and recognition in video', Pattern Recognition, vol. 54, pp. 128-148.
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© 2016 Elsevier Ltd. Text detection and recognition in poor quality video is a challenging problem due to unpredictable blur and distortion effects caused by camera and text movements. This affects the overall performance of the text detection and recognition methods. This paper presents a combined quality metric for estimating the degree of blur in the video/image. Then the proposed method introduces a blind deconvolution model that enhances the edge intensity by suppressing blurred pixels. The proposed deblurring model is compared with other state-of-the-art models to demonstrate its superiority. In addition, to validate the usefulness and the effectiveness of the proposed model, we conducted text detection and recognition experiments on blurred images classified by the proposed model from standard video databases, namely, ICDAR 2013, ICDAR 2015, YVT and then standard natural scene image databases, namely, ICDAR 2013, SVT, MSER. Text detection and recognition results on both blurred and deblurred video/images illustrate that the proposed model improves the performance significantly.

Knee, GC, Combes, J, Ferrie, C & Gauger, EM 2016, 'Weak-value amplification: state of play', Quantum Measurements and Quantum Metrology, vol. 3, no. 1, pp. 32-37.
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Weak values arise in quantum theory when the result of a weak measurement is conditioned on a subsequent strong measurement. The majority of the trials are discarded, leaving only very few successful events. Intriguingly those can display a substantial signal ampli cation. This raises the question of whether weak values carry potential to improve the performance of quantum sensors, and indeed a number of impressive experimental results suggested this may be the case. By contrast, recent theoretical studies have found the opposite: using weak-values to obtain an ampli cation generally worsens metrological performance. This survey summarises the implications of those studies, which call for a reappraisal of weak values’ utility and for further work to reconcile theory and experiment.

Lai, CY, Hsieh, MH & Lu, HF 2016, 'On the MacWilliams Identity for Classical and Quantum Convolutional Codes', IEEE Transactions on Communications, vol. 64, no. 8, pp. 3148-3159.
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© 2016 IEEE. The weight generating functions associated with convolutional codes (CCs) are based on state space realizations or the weight adjacency matrices (WAMs). The MacWilliams identity for CCs on the WAMs was first established by Gluesing-Luerssen and Schneider in the case of minimal encoders, and generalized by Forney. We consider this problem in the viewpoint of constraint codes and obtain a simple and direct proof of this MacWilliams identity in the case of minimal encoders. For our purpose, we choose a different representation for the exact weight generating function (EWGF) of a block code, by defining it as a linear combination of orthonormal vectors in Dirac bra-ket notation. This representation provides great flexibility so that general split weight generating functions and their MacWilliams identities can be easily obtained from the MacWilli ams identity for EWGFs. As a result, we also obtain the MacWilliams identity for the input-parity WAMs of a systematic convolutional code and its dual. Finally, paralleling the development of the classical case, we establish the MacWilliams identity for quantum CCs.

Leung, D & Yu, N 2016, 'Maximum privacy without coherence, zero-error', Journal of Mathematical Physics, vol. 57, no. 9.
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We study the possible difference between the quantum and the private capacities of a quantum channel in the zero-error setting. For a family of channels introduced by Leung et al. [Phys. Rev. Lett. 113, 030512 (2014)], we demonstrate an extreme difference: the zero-error quantum capacity is zero, whereas the zero-error private capacity is maximum given the quantum output dimension.

Li, N, Ferrie, C, Gross, JA, Kalev, A & Caves, CM 2016, 'Fisher-Symmetric Informationally Complete Measurements for Pure States.', Physical Review Letters, vol. 116, no. 18, pp. 180402-180402.
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We introduce a new kind of quantum measurement that is defined to be symmetric in the sense of uniform Fisher information across a set of parameters that uniquely represent pure quantum states in the neighborhood of a fiducial pure state. The measurement is locally informationally complete-i.e., it uniquely determines these parameters, as opposed to distinguishing two arbitrary quantum states-and it is maximal in the sense of a multiparameter quantum Cramér-Rao bound. For a d-dimensional quantum system, requiring only local informational completeness allows us to reduce the number of outcomes of the measurement from a minimum close to but below 4d-3, for the usual notion of global pure-state informational completeness, to 2d-1.

Long, Z, Duckham, M, Li, S & Schockaert, S 2016, 'Indexing large geographic datasets with compact qualitative representation', International Journal of Geographical Information Science, vol. 30, no. 6, pp. 1072-1094.
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© 2015 Taylor & Francis This paper develops a new mechanism to efficiently compute and compactly store qualitative spatial relations between spatial objects, focusing on topological and directional relations for large datasets of region objects. The central idea is to use minimum bounding rectangles (MBRs) to approximately represent region objects with arbitrary shape and complexity and only store spatial relations that cannot be unambiguously inferred from the relations of corresponding MBRs. We demonstrate, both in theory and practice, that our approach requires considerably less construction time and storage space, and can answer queries more efficiently than the state-of-the-art methods.

Lu, D, Xin, T, Yu, N, Ji, Z, Chen, J, Long, G, Baugh, J, Peng, X, Zeng, B & Laflamme, R 2016, 'Tomography is Necessary for Universal Entanglement Detection with Single-Copy Observables', PHYSICAL REVIEW LETTERS, vol. 116, no. 23.
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Ma, X, Jackson, T, Zhou, H, Chen, J, Lu, D, Mazurek, MD, Fisher, KAG, Peng, X, Kribs, D, Resch, KJ, Ji, Z, Zeng, B & Laflamme, R 2016, 'Pure-state tomography with the expectation value of Pauli operators', PHYSICAL REVIEW A, vol. 93, no. 3.
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Motes, KR, Gilchrist, A & Rohde, PP 2016, 'Quantum random walks on congested lattices and the effect of dephasing', Scientific Reports, vol. 6, pp. 1-10.
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We consider quantum random walks on congested lattices and contrast them to classical random walks. Congestion is modelled on lattices that contain static defects which reverse the walkerâ €™ s direction. We implement a dephasing process after each step which allows us to smoothly interpolate between classical and quantum random walks as well as study the effect of dephasing on the quantum walk. Our key results show that a quantum walker escapes a finite boundary dramatically faster than a classical walker and that this advantage remains in the presence of heavily congested lattices.

Motes, KR, Mann, RL, Olson, JP, Studer, NM, Bergeron, EA, Gilchrist, A, Dowling, JP, Berry, DW & Rohde, PP 2016, 'Efficient recycling strategies for preparing large Fock states from single-photon sources: Applications to quantum metrology', PHYSICAL REVIEW A, vol. 94, no. 1.
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Moyle, W, Jones, C, Sung, B, Bramble, M, O Dwyer, S, Blumenstein, M & Estivill-Castro, V 2016, 'What Effect Does an Animal Robot Called CuDDler Have on the Engagement and Emotional Response of Older People with Dementia? A Pilot Feasibility Study', International Journal of Social Robotics, vol. 8, no. 1, pp. 145-156.
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© 2015, Springer Science+Business Media Dordrecht. The development of companion animal robots is of growing interest. These robots have recently been marketed to older adults with dementia as a means of encouraging social engagement and reducing behavioural and psychological symptoms of dementia. This paper outlines the results of a pilot study that sought to assess the feasibility and effect of using a robotic companion animal called CuDDler on engagement and emotional states of five older adults with dementia living in nursing home care. CuDDler is a prototype robot developed in Singapore. Despite their cognitive decline, the study participants raised a number of concerns regarding the feasibility and tolerability of CuDDler. The effectiveness of CuDDler was also limited in these participants, although one participant with visual agnosia benefited greatly from the one-on-one experience. The findings demonstrate the importance of companion robots being developed that are of an appropriate size, weight and shape for older people, including those with dementia, and a realistic animal shape that does not encourage thoughts of it being a toy. Our conclusions indicate the need for further studies on the development and use of companion robots, and investigation of the comparative benefits of social robots both compared to and in association with human interactions.

Nagayama, S, Choi, BS, Devitt, S, Suzuki, S & Van Meter, R 2016, 'Interoperability in encoded quantum repeater networks', Physical Review A, vol. 93, no. 4.
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© 2016 American Physical Society. The future of quantum repeater networking will require interoperability between various error-correcting codes. A few specific code conversions and even a generalized method are known, however, no detailed analysis of these techniques in the context of quantum networking has been performed. In this paper we analyze a generalized procedure to create Bell pairs encoded heterogeneously between two separate codes used often in error-corrected quantum repeater network designs. We begin with a physical Bell pair and then encode each qubit in a different error-correcting code, using entanglement purification to increase the fidelity. We investigate three separate protocols for preparing the purified encoded Bell pair. We calculate the error probability of those schemes between the Steane [[7,1,3]] code, a distance-3 surface code, and single physical qubits by Monte Carlo simulation under a standard Pauli error model and estimate the resource efficiency of the procedures. A local gate error rate of 10-3 allows us to create high-fidelity logical Bell pairs between any of our chosen codes. We find that a postselected model, where any detected parity flips in code stabilizers result in a restart of the protocol, performs the best.

Nemoto, K, Trupke, M, Devitt, SJ, Scharfenberger, B, Buczak, K, Schmiedmayer, J & Munro, WJ 2016, 'Photonic Quantum Networks formed from NV^- centers', Scientific Reports, vol. 6.
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In this article we present a simple repeater scheme based on the negatively-charged nitrogen vacancy centre in diamond. Each repeater node is built from modules comprising an optical cavity containing a single NV-, with one nuclear spin from 15N as quantum memory. The module uses only deterministic processes and interactions to achieve high fidelity operations (>99%), and modules are connected by optical fiber. In the repeater node architecture, the processes between modules by photons can be in principle deterministic, however current limitations on optical components lead the processes to be probabilistic but heralded. Our resource-modest repeater architecture contains two modules at each node, and the repeater nodes are then connected by entangled photon pairs. We discuss the performance of such a quantum repeater network with modest resources and then incorporate more resource-intense strategies step by step. Our architecture should allow large-scale quantum information networks with existing or near future technology.

Paler, A, Devitt, SJ & Fowler, AG 2016, 'Synthesis of Arbitrary Quantum Circuits to Topological Assembly', Scientific Reports, vol. 6.
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© The Author(s) 2016. Given a quantum algorithm, it is highly nontrivial to devise an efficient sequence of physical gates implementing the algorithm on real hardware and incorporating topological quantum error correction. In this paper, we present a first step towards this goal, focusing on generating correct and simple arrangements of topological structures that correspond to a given quantum circuit and largely neglecting their efficiency. We detail the many challenges that will need to be tackled in the pursuit of efficiency. The software source code can be consulted at https://github.com/alexandrupaler/tqec.

Paler, A, Wille, R & Devitt, SJ 2016, 'Wire recycling for quantum circuit optimization', Physical Review A, vol. 94, no. 4.
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© 2016 American Physical Society. Quantum information processing is expressed using quantum bits (qubits) and quantum gates which are arranged in terms of quantum circuits. Here, each qubit is associated with a quantum circuit wire which is used to conduct the desired operations. Most of the existing quantum circuits allocate a single quantum circuit wire for each qubit and hence introduce significant overhead. In fact, qubits are usually not needed during the entire computation, only between their initialization and measurement. Before and after that, corresponding wires may be used by other qubits. In this work, we propose a solution which exploits this fact in order to optimize the design of quantum circuits with respect to the required wires. To this end, we introduce a representation of the lifetimes of all qubits which is used to analyze the respective need for wires. Based on this analysis, a method is proposed which "recycles" the available wires and, as a result, reduces the size of the resulting circuit. Numerical tests based on established reversible and fault-tolerant quantum circuits confirm that the proposed solution reduces the number of wires by more than 90% compared to unoptimized quantum circuits.

Pfister, C, Kaniewski, J, Tomamichel, M, Mantri, A, Schmucker, R, McMahon, N, Milburn, G & Wehner, S 2016, 'A universal test for gravitational decoherence.', Nature Communications, vol. 7, pp. 13022-13022.
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Quantum mechanics and the theory of gravity are presently not compatible. A particular question is whether gravity causes decoherence. Several models for gravitational decoherence have been proposed, not all of which can be described quantum mechanically. Since quantum mechanics may need to be modified, one may question the use of quantum mechanics as a calculational tool to draw conclusions from the data of experiments concerning gravity. Here we propose a general method to estimate gravitational decoherence in an experiment that allows us to draw conclusions in any physical theory where the no-signalling principle holds, even if quantum mechanics needs to be modified. As an example, we propose a concrete experiment using optomechanics. Our work raises the interesting question whether other properties of nature could similarly be established from experimental observations alone-that is, without already having a rather well-formed theory of nature to make sense of experimental data.

Su, G, Feng, Y, Chen, T & Rosenblum, DS 2016, 'Asymptotic Perturbation Bounds for Probabilistic Model Checking with Empirically Determined Probability Parameters', IEEE TRANSACTIONS ON SOFTWARE ENGINEERING, vol. 42, no. 7, pp. 623-639.
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Sutter, D, Tomamichel, M & Harrow, AW 2016, 'Strengthened Monotonicity of Relative Entropy via Pinched Petz Recovery Map', IEEE Transactions on Information Theory, vol. 62, no. 5, pp. 2907-2913.
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The quantum relative entropy between two states satisfies a monotonicity property meaning that applying the same quantum channel to both states can never increase their relative entropy. It is known that this inequality is only tight when there is a recovery map that exactly reverses the effects of the quantum channel on both states. In this paper, we strengthen this inequality by showing that the difference of relative entropies is bounded below by the measured relative entropy between the first state and a recovered state from its processed version. The recovery map is a convex combination of rotated Petz recovery maps and perfectly reverses the quantum channel on the second state. As a special case, we reproduce recent lower bounds on the conditional mutual information, such as the one proved by Fawzi and Renner. Our proof only relies on the elementary properties of pinching maps and the operator logarithm

Tomamichel, M, Berta, M & Renes, JM 2016, 'Quantum coding with finite resources', NATURE COMMUNICATIONS, vol. 7.
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Van Meter, R & Devitt, SJ 2016, 'The Path to Scalable Distributed Quantum Computing', Computer, vol. 49, no. 9, pp. 31-42.
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© 2016 IEEE. Researchers are fabricating quantum processors powerful enough to execute small instances of quantum algorithms. Scalability concerns are motivating distributed-memory multicomputer architectures, and experimental efforts have demonstrated some of the building blocks for such a design. Numberous systems are emerging with the goal of enabling local and distributed quantum computing.

Wang, HY, Zheng, WQ, Yu, NK, Li, KR, Lu, DW, Xin, T, Li, C, Ji, ZF, Kribs, D, Zeng, B, Peng, XH & Du, JF 2016, 'Quantum state and process tomography via adaptive measurements', Science China: Physics, Mechanics and Astronomy, vol. 59, no. 10.
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© 2016, Science China Press and Springer-Verlag Berlin Heidelberg.We investigate quantum state tomography (QST) for pure states and quantum process tomography (QPT) for unitary channels via adaptive measurements. For a quantum system with a d-dimensional Hilbert space, we first propose an adaptive protocol where only 2d − 1 measurement outcomes are used to accomplish the QST for all pure states. This idea is then extended to study QPT for unitary channels, where an adaptive unitary process tomography (AUPT) protocol of d2+d−1 measurement outcomes is constructed for any unitary channel. We experimentally implement the AUPT protocol in a 2-qubit nuclear magnetic resonance system. We examine the performance of the AUPT protocol when applied to Hadamard gate, T gate (π/8 phase gate), and controlled-NOT gate, respectively, as these gates form the universal gate set for quantum information processing purpose. As a comparison, standard QPT is also implemented for each gate. Our experimental results show that the AUPT protocol that reconstructing unitary channels via adaptive measurements significantly reduce the number of experiments required by standard QPT without considerable loss of fidelity.

Wang, X & Duan, R 2016, 'Improved semidefinite programming upper bound on distillable entanglement', PHYSICAL REVIEW A, vol. 94, no. 5.
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Wu, Y, Shivakumara, P, Lu, T, Tan, CL, Blumenstein, M & Kumar, GH 2016, 'Contour restoration of text components for recognition in video/scene images', IEEE Transactions on Image Processing, vol. 25, no. 12, pp. 5622-5634.
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Text recognition in video/natural scene images has gained significant attention in the field of image processing in many computer vision applications, which is much more challenging than recognition in plain background images. In this work, we aim to restore complete character contours in video/scene images from gray values, in contrast to the conventional techniques that consider edge images/binary information as inputs for text detection and recognition. We explore and utilize the strengths of zero crossing points given by the Laplacian to identify stroke candidate pixels (SPC). For each SPC pair, we propose new symmetry features based on gradient magnitude and Fourier phase angles to identify probable stroke candidate pairs (PSCP). The same symmetry properties are proposed at the PSCP level to choose seed stroke candidate pairs (SSCP). Finally, an iterative algorithm is proposed for SSCP to restore complete character contours. Experimental results on benchmark databases, namely, the ICDAR family of video and natural scenes, Street View Data (SVT), and MSRA datasets, show that the proposed technique outperforms the existing techniques in terms of both quality measures and recognition rate. We also show that character contour restoration is effective for text detection in video and natural scene images.

Yu, N 2016, 'Separability of a mixture of Dicke states', PHYSICAL REVIEW A, vol. 94, no. 6.
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Adak, C, Chaudhuri, BB & Blumenstein, M 2016, 'Named Entity Recognition from Unstructured Handwritten Document Images', Proceedings - 12th IAPR International Workshop on Document Analysis Systems, DAS 2016, International Workshop on Document Analysis Systems, IEEE, Santorini, Greece, pp. 375-380.
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© 2016 IEEE.Named entity recognition is an important topic in the field of natural language processing, whereas in document image processing, such recognition is quite challenging without employing any linguistic knowledge. In this paper we propose an approach to detect named entities (NEs) directly from offline handwritten unstructured document images without explicit character/word recognition, and with very little aid from natural language and script rules. At the preprocessing stage, the document image is binarized, and then the text is segmented into words. The slant/skew/baseline corrections of the words are also performed. After preprocessing, the words are sent for NE recognition. We analyze the structural and positional characteristics of NEs and extract some relevant features from the word image. Then the BLSTM neural network is used for NE recognition. Our system also contains a post-processing stage to reduce the true NE rejection rate. The proposed approach produces encouraging results on both historical and modern document images, including those from an Australian archive, which are reported here for the very first time.

Adak, C, Chaudhuri, BB & Blumenstein, M 2016, 'Offline cursive Bengali word recognition using CNNs with a recurrent model', Proceedings of International Conference on Frontiers in Handwriting Recognition, ICFHR, International Conference on Frontiers in Handwriting Recognition, IEEE, Shenzhen, China, pp. 429-434.
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© 2016 IEEE. This paper deals with offline handwritten word recognition of a major Indic script: Bengali. Due to the structure of this script, the characters (mostly ortho-syllables) are frequently overlapping and hard to segment, especially when the writing is cursive. Individual character recognition and the combination of outputs can increase the likelihood of errors. Instead, a better approach can be sending the whole word to a suitable recognizer. Here we use the Convolutional Neural Network (CNN) integrated with a recurrent model for this purpose. Long short-term memory blocks are used as hidden units. Also, the CNN-derived features are employed in a recurrent model with a CTC (Connectionist Temporal Classification) layer to get the output. We have tested our method on three datasets: (a) a publicly available dataset, (b) a new dataset generated by our research group and (c) an unconstrained dataset. The dataset (a) contains 17,091 words, while our dataset (b) contains 107,550 number of words in total. In addition to these, the dataset (c) is comprised of 5,223 words. We have compared our results with those of some earlier work in the area and have found improved performance, which is due to the novel integration of CNNs with the recurrent model.

Adak, C, Chaudhuri, BB & Blumenstein, M 2016, 'Writer identification by training on one script but testing on another', Proceedings - International Conference on Pattern Recognition, International Conference on Pattern Recognition, Mexico, pp. 1153-1158.
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© 2016 IEEE. This paper deals with identifying a writer from his/her offline handwriting. In a multilingual country where a writer can scribe in multiple scripts, writer identification becomes challenging when we have individual handwriting data in one script while we need to verify/identify a writer from handwriting in another script. In this paper such an issue is addressed with two scripts: English and Bengali. Here we model the task as a classification problem, where training data contains only Bengali handwritten samples and testing is performed on English handwritten texts. This work is based on the understanding that a writer has some inherent stroke characteristics that are independent of the script in which (s)he writes. In this work, some implicit structural and statistical features are extracted, and multiple classifiers are employed for writer identification. Many training sessions are run on a database of 100 writers and the performances are analyzed. We have obtained encouraging results on this database, which show the effectiveness of our method.

Alaei, A, Conte, D, Blumenstein, M & Raveaux, R 2016, 'Document Image Quality Assessment Based on Texture Similarity Index', Proceedings - 12th IAPR International Workshop on Document Analysis Systems, DAS 2016, International Workshop on Document Analysis Systems, IEEE, Santorini, Greece, pp. 132-137.
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© 2016 IEEE.In this paper, a full reference document image quality assessment (FR DIQA) method using texture features is proposed. Local binary patterns (LBP) as texture features are extracted at the local and global levels for each image. For each extracted LBP feature set, a similarity measure called the LBP similarity index (LBPSI) is computed. A weighting strategy is further proposed to improve the LBPSI obtained based on local LBP features. The LBPSIs computed for both local and global features are then combined to get the final LBPSI, which also provides the best performance for DIQA. To evaluate the proposed method, two different datasets were used. The first dataset is composed of document images, whereas the second one includes natural scene images. The mean human opinion scores (MHOS) were considered as ground truth for performance evaluation. The results obtained from the proposed LBPSI method indicate a significant improvement in automatically/accurately predicting image quality, especially on the document image-based dataset.

Alaei, F, Alaei, A, Blumenstein, M & Pal, U 2016, 'A brief review of document image retrieval methods: Recent advances', Proceedings of the International Joint Conference on Neural Networks, IEEE International Joint Conference on Neural Networks, IEEE, Vancouver, CANADA, pp. 3500-3507.
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© 2016 IEEE.Due to the rapid increase of different digitized documents, the development of a system to automatically retrieve document images from a large collection of structured and unstructured document images is in high demand. Many techniques have been developed to provide an efficient and effective way for retrieving and organizing these document images in the literature. This paper provides an overview of the methods which have been applied for document image retrieval over recent years. It has been found that from a textual perspective, more attention has been paid to the feature extraction methods without using OCR.

Alaei, F, Alaei, A, Pal, U & Blumenstein, M 2016, 'Document Image Retrieval Based on Texture Features: A Recognition-Free Approach', 2016 International Conference on Digital Image Computing: Techniques and Applications, DICTA 2016, Digital Image Computing Techniques and Applications, IEEE, Gold Coast, Australia, pp. 1-7.
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© 2016 IEEE.The tendency of current technology is towards a paperless world. Due to the rapid increase of digitized documents, providing a fast and easy method for retrieval is in high demand. The aim of this paper is to examine the effectiveness of texture features for document image retrieval. Thus, segmentation-free document image retrieval using a binary texture method is proposed. In the proposed approach, local features are extracted, local grey-level structures are summarised, and their distribution is characterised using global features. The assumption is that texture properties in the text regions and non-text regions of the document images are different. This assumption is used to rank the available document images and retrieve only those, which have greatest visual similarity to a given query. The under-sampled image and sub-images of the original image are further considered to improve the retrieval results, which are up to 76.0% in the first ranking and 96.2% in the Top-10 ranking. The Media Team Oulu Document Database, which is a heterogeneous database that offers a great variety of page layouts and contents, is used for experimentation.

Alaei, F, Alaei, A, Pal, U & Blumenstein, M 2016, 'Document Image Retrieval Based on Texture Features: A Recognition-Free Approach', 2016 INTERNATIONAL CONFERENCE ON DIGITAL IMAGE COMPUTING: TECHNIQUES AND APPLICATIONS (DICTA), International Conference on Digital Image Computing - Techniques and Applications (DICTA), IEEE, Gold Coast, AUSTRALIA, pp. 456-462.

Antonacopoulos, A, Gatos, B, Blumenstein, M, Lladós, J & Lopresti, D 2016, 'Message from the General Chairs and Program Chairs', Proceedings - 12th IAPR International Workshop on Document Analysis Systems, DAS 2016, p. xi.
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Berta, M, Fawzi, O & Tomamichel, M 2016, 'Exploiting variational formulas for quantum relative entropy', Proceedings IEEE International Symposium on Information Theory (ISIT 2016), IEEE International Symposium on Information Theory, IEEE, Barcelona, Spain, pp. 2844-2848.
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The relative entropy is the basic concept underlying various information measures like entropy, conditional entropy and mutual information. Here, we discuss how to make use of variational formulas for measured relative entropy and quantum relative entropy for understanding the additivity properties of various entropic quantities that appear in quantum information theory. In particular, we show that certain lower bounds on quantum conditional mutual information are superadditive.

Bremner, MJ, Montanaro, A & Shepherd, D 2016, 'Average-case complexity versus approximate simulation of commuting quantum computations', 19th Conference on Quantum Information Processing, Banff, Canada.

Broadbent, A, Ji, Z, Song, F & Watrous, J 2016, 'Zero-Knowledge Proof Systems for QMA', Proceedings - Annual IEEE Symposium on Foundations of Computer Science, FOCS, pp. 31-40.
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© 2016 IEEE. Prior work has established that all problems in NP admit classical zero-knowledge proof systems, and under reasonable hardness assumptions for quantum computations, these proof systems can be made secure against quantum attacks. We prove a result representing a further quantum generalization of this fact, which is that every problem in the complexity class QMA has a quantum zero-knowledge proof system. More specifically, assuming the existence of an unconditionally binding and quantum computationally concealing commitment scheme, we prove that every problem in the complexity class QMA has a quantum interactive proof system that is zero-knowledge with respect to efficient quantum computations. Our QMA proof system is sound against arbitrary quantum provers, but only requires an honest prover to perform polynomial-time quantum computations, provided that it holds a quantum witness for a given instance of the QMA problem under consideration.

Chakraborty, A & Blumenstein, M 2016, 'Marginal Noise Reduction in Historical Handwritten Documents - A Survey', Proceedings - 12th IAPR International Workshop on Document Analysis Systems, DAS 2016, International Workshop on Document Analysis Systems, IEEE, GREECE, pp. 323-328.
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© 2016 IEEE.This paper presents a survey on different approaches for removing the marginal noise from document images, and anlaysing the research challenges of those methods relating to handwritten historical datasets. In this survey, historical documents collected from Australian Archives and Libraries are introduced and the associated layout complexities of those document images are also described. Benchmarking other historical databases related to this work is also discussed. This survey discusses the difficulties and suitability of the state-of-the-art methods to remove marginal noise as well as preserving the text content from handwritten historical documents. This survey helps researchers to identify appropriate methods according to the associated marginal noise and also illustrates their drawbacks in order to make suggestions for developing approaches, which are more general and robust for any datasets.

Chakraborty, A & Blumenstein, M 2016, 'Preserving Text Content from Historical Handwritten Documents', Proceedings - 12th IAPR International Workshop on Document Analysis Systems, DAS 2016, International Workshop on Document Analysis Systems, IEEE, Santorini, Italy, pp. 329-334.
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© 2016 IEEE.We propose a holistic, dynamic method to preserve text content with zero tolerance while removing marginal noise for historical handwritten document images. The key idea is to identify and analyze the region between the sharp peak at the edge and page frame of the text content at each margin. Depending on the proximity of the sharp peak to the text, the text content is then extracted from the document image. This method automatically adapts thresholds for each single document image and is directly applicable to gray-scale images. The proposed method is evaluated on four diverse handwritten historical datasets: Queensland State Archive (QSA), Saint Gall, Parzival and the Prosecution Project. Experimental results show that the proposed method achieves higher accuracy compared with other methods tested on the Saint Gall and Parzival datasets, whilst for the other two Australian datasets, which have been introduced here for the first time, the results are very encouraging.

Cui, SX, Ji, Z, Yu, N & Zeng, B 2016, 'Quantum Capacities for Entanglement Networks', Proceedings of the 2016 IEEE International Symposium on Information Theory (ISIT), IEEE International Symposium on Information Theory, IEEE, Barcelona, Spain, pp. 1685-1689.
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We discuss quantum capacities for two types of entanglement networks: Q for the quantum repeater network with free classical communication, and R for the tensor network as the rank of the linear operation represented by the tensor network. We find that Q always equals R in the regularized case for the same network graph. However, the relationships between the corresponding one-shot capacities Q1 and R1 are more complicated, and the min-cut upper bound is in general not achievable. We show that the tensor network can be viewed as a stochastic protocol with the quantum repeater network, such that R1 is a natural upper bound of Q1. We analyze the possible gap between R1 and Q1 for certain networks, and compare them with the one-shot classical capacity of the corresponding classical network.

Das, A, Mondal, P, Pal, U, Ferrer, MA & Blumenstein, M 2016, 'Fast and efficent multimodal eye biometrics using projective dictionary pair learning', 2016 IEEE Congress on Evolutionary Computation, CEC 2016, IEEE Congress on Evolutionary Computation, IEEE, Vancouver, Canada, pp. 1402-1408.
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© 2016 IEEE.This work proposes a projective pairwise dictionary learning-based approach for fast and efficient multimodal eye biometrics. The work uses a faster Projective pairwise Discriminative Dictionary Learning (DL) in contrast to the traditional DL which uses synthesis DL. Projective Pairwise Discriminative Dictionary (PPDD) uses a synthesis dictionary and an analysis dictionary jointly to achieve the goal of pattern representation and discrimination. As the PPDD process of DL is in contrast to the use of l0 or l1-norm sparsity constraints on the representation coefficients adopted in most traditional DL, it works faster than other DL. Moreover, the blending of synthesis dictionary and an analysis dictionary also enhance the feature representation of the complex eye patterns. We employed the combination of sclera and iris traits to establish multimodal biometrics. The experimental study and analysis conducted fulfill the hypothesis we considered. In this work we employed a part of the UBIRIS version 1 dataset to conduct the experiments.

Das, A, Pal, U, Ferrer, MA & Blumenstein, M 2016, 'SSRBC 2016: Sclera Segmentation and Recognition Benchmarking Competition', 2016 International Conference on Biometrics, ICB 2016, International Conference on Biometrics (ICB), IEEE, Halmstad, Sweden.
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© 2016 IEEE.This article reports and summarizes the results of a competition on sclera segmentation and recognition benchmarking, called Sclera Segmentation and Recognition Benchmarking Competition 2016 (SSRBC 2016). It was organized in the context of the 9th IAPR International Conference on Biometrics (ICB 2016). The goal of this competition was to record the recent developments in sclera segmentation and recognition, and also to gain the attention of researchers on this subject of biometrics. In this regard, we have used a multi-angle sclera dataset (MASD version 1). It is comprised of 2624 images taken from both the eyes of 82 identities. Therefore, it consists of images of 164 (82∗2) different eyes. We have prepared a manual segmentation mask of these images to create the baseline for both tasks. We have, furthermore, adopted precision and recall based statistical measures to evaluate the effectiveness of the segmentation and the ranks of the competing algorithms. The recognition accuracy measure has been employed to measure the recognition task. To summarize, twelve participants registered for the competition, and among them, three participants submitted their algorithms/ systems for the segmentation task and two their recognition algorithm. The results produced by these algorithms reflect developments in the literature of sclera segmentation and recognition, employing cutting edge segmentation techniques. Along with the algorithms of three competing teams and their results, the MASD version 1 dataset will also be freely available for research purposes from the organizer's website. The competition also demonstrates the recent interests of researchers from academia as well as industry on this subject of biometrics.

Duan, R, Guo, C, Li, CK & Li, Y 2016, 'Parallel distinguishability of quantum operations', Proceedings of the IEEE International Symposium on Information Theory (ISIT), IEEE International Symposium on Information Theory, IEEE, Barcelona, Spain, pp. 2259-2263.
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© 2016 IEEE.We find that the perfect distinguishability of two quantum operations by a parallel scheme depends only on an operator subspace generated from their Choi-Kraus operators. We further show that any operator subspace can be obtained from two quantum operations in such a way. This connection enables us to study the parallel distinguishability of operator subspaces directly without explicitly referring to the underlining quantum operations. We obtain a necessary and sufficient condition for the parallel distinguishability of an operator subspace that is either one-dimensional or Hermitian. In both cases the condition is equivalent to the non-existence of positive definite operator in the subspace, and an optimal discrimination protocol is obtained. Finally, we provide more examples to show that the non-existence of positive definite operator is sufficient for many other cases, but in general it is only a necessary condition.

Grochow, JA, Mulmuley, KD & Qiao, Y 2016, 'Boundaries of VP and VNP', Leibniz International Proceedings in Informatics, LIPIcs, International Colloquium on Automata Languages and Programming, Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik, Rome, Italy.
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One fundamental question in the context of the geometric complexity theory approach to the VP vs. VNP conjecture is whether VP = !VP, where VP is the class of families of polynomials that can be computed by arithmetic circuits of polynomial degree and size, and VP is the class of families of polynomials that can be approximated infinitesimally closely by arithmetic circuits of polynomial degree and size. The goal of this article is to study the conjecture in (Mulmuley, FOCS 2012) that !VP is not contained in VP. Towards that end, we introduce three degenerations of VP (i.e., sets of points in VP), namely the stable degeneration Stable-VP, the Newton degeneration Newton-VP, and the p-definable one-parameter degeneration VP*. We also introduce analogous degenerations of VNP. We show that Stable-VP subseteq Newton-VP subseteq VP* subseteq VNP, and Stable-VNP = Newton-VNP = VNP* = VNP. The three notions of degenerations and the proof of this result shed light on the problem of separating VP from VP. Although we do not yet construct explicit candidates for the polynomial families in !VP\VP, we prove results which tell us where not to look for such families. Specifically, we demonstrate that the families in Newton-VP \VP based on semi-invariants of quivers would have to be nongeneric by showing that, for many finite quivers (including some wild ones), Newton degeneration of any generic semi-invariant can be computed by a circuit of polynomial size. We also show that the Newton degenerations of perfect matching Pfaffians, monotone arithmetic circuits over the reals, and Schur polynomials have polynomial-size circuits.

Haah, J, Harrow, AW, Ji, Z, Wu, X & Yu, N 2016, 'Sample-optimal tomography of quantum states', STOC '16 Proceedings of the forty-eighth annual ACM symposium on Theory of Computing, ACM symposium on Theory of Computing, ACM, Cambridge, MA, USA, pp. 913-925.
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It is a fundamental problem to decide how many copies of an unknown mixed quantum state are necessary and sufficient to determine the state. This is the quantum analogue of the problem of estimating a probability distribution given some number of samples. Previously, it was known only that estimating states to error є in trace distance required O(dr2/є2) copies for a d-dimensional density matrix of rank r. Here, we give a measurement scheme (POVM) that uses O( (dr/ δ ) ln(d/δ) ) copies to estimate ρ to error δ in infidelity. This implies O( (dr / є2)· ln(d/є) ) copies suffice to achieve error є in trace distance. For fixed d, our measurement can be implemented on a quantum computer in time polynomial in n. We also use the Holevo bound from quantum information theory to prove a lower bound of Ω(dr/є2)/ log(d/rє) copies needed to achieve error є in trace distance. This implies a lower bound Ω(dr/δ)/log(d/rδ) for the estimation error δ in infidelity. These match our upper bounds up to log factors. Our techniques can also show an Ω(r2d/δ) lower bound for measurement strategies in which each copy is measured individually and then the outcomes are classically post-processed to produce an estimate. This matches the known achievability results and proves for the first time that such “product” measurements have asymptotically suboptimal scaling with d and r.

Ji, Z 2016, 'Classical verification of quantum proofs', STOC '16 Proceedings of the forty-eighth annual ACM symposium on Theory of Computing, ACM symposium on Theory of Computing, ACM, Cambridge, MA, USA, pp. 885-898.
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We present a classical interactive protocol that verifies the validity of a quantum witness state for the local Hamiltonian problem. It follows from this protocol that approximating the non-local value of a multi-player one-round game to inverse polynomial precision is QMA-hard. Our work makes an interesting connection between the theory of QMA-completeness and Hamiltonian complexity on one hand and the study of non-local games and Bell inequalities on the other.

Khare, V, Blumenstein, M & Lu, T 2016, 'A quad tree based method for blurred and non-blurred video text frames classification through quality metrics', Proceedings of the 2016 23rd International Conference on Pattern Recognition (ICPR), International Conference on Pattern Recognition, IEEE, Cancun, Mexico, pp. 4023-4028.
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Blur is a common artifact in video, which adds more complexity to text detection and recognition. To achieve good accuracies for text detection and recognition, this paper suggests a new method for classifying blurred and non-blurred frames in video. We explore quality metrics, namely, BRISQUE, NRIQA, GPC and SI, in a new way for classification. We estimate the values of these metrics with the help of predefined samples called reference values. To widen the difference between metric values for better classification, we introduce scaling factors as a non-linear sigmoidal function, which considers the metric of each current frame and its reference and results in templates. Based on the characteristics of metrics, the proposed method finds a relationship between the metrics to derive rules for classification. To classify the frame containing local blur, we explore quad tree division with classification rules which divide non-blurred blocks to identify local blur. We use standard databases, namely, ICDAR 2013, ICDAR 2015 and YVT videos for experimentation, and evaluate the proposed method in terms of text detection and recognition rates given by text detection and binarization methods before and after classification.

Lee, JH, Li, S, Long, Z & Sioutis, M 2016, 'On Redundancy in Simple Temporal Networks', Frontiers in Artificial Intelligence and Applications, European Conference on Artificial Intelligence, AAAI Press, Netherlands, pp. 828-836.
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The Simple Temporal Problem (STP) has been widely used in various applications to schedule tasks. For dynamical systems, scheduling needs to be efficient and flexible to handle uncertainty and perturbation. To this end, modern approaches usually encode the temporal information as an STP instance. This representation contains redundant information, which can not only take a significant amount of storage space, but also make scheduling inefficient due to the non-concise representation. In this paper, we investigate the problem of simplifying an STP instance by removing redundant information. We show that such a simplification can result in a unique minimal representation without loss of temporal information, and present an efficient algorithm to achieve this task. Evaluation on a large benchmark dataset of STP exhibits a significant reduction in redundant information for the involved instances.

Li, Y, Song, L, Feng, Y & Zhang, L 2016, 'Verify LTL with Fairness Assumptions Efficiently', Proceedings of the International Symposium on Temporal Representation and Reasoning (TIME), International Symposium on Temporal Representation and Reasoning, IEEE, Kongens Lyngby, Denmark, pp. 41-50.
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© 2016 IEEE.This paper deals with model checking problems with respect to LTL properties under fairness assumptions. We first present an efficient algorithm to deal with a fragment of fairness assumptions and then extend the algorithm to handle arbitrary ones. Notably, by making use of some syntactic transformations, our algorithm avoids constructing corresponding Büchi automata for the whole fairness assumptions, which can be very large in practice. We implement our algorithm in NuSMV and consider a large selection of formulas. Our experiments show that in many cases our approach exceeds the automata-theoretic approach up to several orders of magnitude, in both time and memory.

Long, Z, Schockaert, S & Li, S 2016, 'Encoding large RCC8 scenarios using rectangular pseudo-solutions', Principles of Knowledge Representation and Reasoning: Proceedings of the 15th International Conference, KR 2016, International Conference on Principles of Knowledge Representation and Reasoning, Association for the Advancement of Artificial Intelligence, Cape Town, South Africa, pp. 463-472.
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Copyright © 2016, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved.Most approaches in the field of qualitative spatial reasoning (QSR) use constraint networks to encode spatial scenarios. The size of these networks is quadratic in the number of variables, which has severely limited the real-world application of QSR. In this paper, we propose another representation of spatial scenarios, in which each variable is associated with one or more rectangles. Instead of requiring these rectangles to define a solution of the corresponding constraint network, we construct sequences of rectangles that define partial solutions to progressively weaker constraint networks. We present experimental results that illustrate the effectiveness of this strategy.

Long, Z, Sioutis, M & Li, S 2016, 'Efficient path consistency algorithm for large qualitative constraint networks', Proceedings of the Twenty-Fifth International Joint Conference on Artificial Intelligence, International Joint Conference on Artificial Intelligence, AAAI Press, New York City, USA, pp. 1202-1208.
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We propose a new algorithm called DPC+ to enforce partial path consistency (PPC) on qualitative constraint networks. PPC restricts path consistency (PC) to a triangulation of the underlying constraint graph of a network. As PPC retains the sparseness of a constraint graph, it can make reasoning tasks such as consistency checking and minimal labelling of large qualitative constraint networks much easier to tackle than PC. For qualitative constraint networks defined over any distributive subalgebra of well-known spatio-temporal calculi, such as the Region Connection Calculus and the Interval Algebra, we show that DPC+ can achieve PPC very fast. Indeed, the algorithm enforces PPC on a qualitative constraint network by processing each triangle in a triangulation of its underlying constraint graph at most three times. Our experiments demonstrate significant improvements of DPC+ over the state-of-the-art PPC enforcing algorithm.

Pal, S, Alaei, A, Pal, U & Blumenstein, M 2016, 'Performance of an Off-Line Signature Verification Method Based on Texture Features on a Large Indic-Script Signature Dataset', Proceedings - 12th IAPR International Workshop on Document Analysis Systems, DAS 2016, International Workshop on Document Analysis Systems, IEEE, Santorini, Italy, pp. 72-77.
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© 2016 IEEE.In this paper, a signature verification method based on texture features involving off-line signatures written in two different Indian scripts is proposed. Both Local Binary Patterns (LBP) and Uniform Local Binary Patterns (ULBP), as powerful texture feature extraction techniques, are used for characterizing off-line signatures. The Nearest Neighbour (NN) technique is considered as the similarity metric for signature verification in the proposed method. To evaluate the proposed verification approach, a large Bangla and Hindi off-line signature dataset (BHSig260) comprising 6240 (260×24) genuine signatures and 7800 (260×30) skilled forgeries was introduced and further used for experimentation. We further used the GPDS-100 signature dataset for a comparison. The experiments were conducted, and the verification accuracies were separately computed for the LBP and ULBP texture features. There were no remarkable changes in the results obtained applying the LBP and ULBP features for verification when the BHSig260 and GPDS-100 signature datasets were used for experimentation.

Sioutis, M, Long, Z & Li, S 2016, 'Efficiently reasoning about qualitative constraints through variable elimination', ACM International Conference Proceeding Series, Hellenic Conference on Artificial Intelligence (SETN), Association for Computing Machinery Digital Library, Thessaloniki, Greece.
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© 2016 ACM.We introduce, study, and evaluate a novel algorithm in the context of qualitative constraint-based spatial and temporal reasoning, that is based on the idea of variable elimination, a simple and general exact inference approach in probabilistic graphical models. Given a qualitative constraint network M, our algorithm enforces a particular directional local consistency on M, which we denote by ←-consistency. Our discussion is restricted to distributive subclasses of relations, i.e., sets of relations closed under converse, intersection, and weak composition and for which weak composition distributes over non-empty intersections for all of their relations. We demonstrate that enforcing ←-consistency on a given qualitative constraint network defined over a distributive subclass of relations allows us to decide its satisfiability. The experimentation that we have conducted with random and real-world qualitative constraint networks defined over a distributive subclass of relations of the Region Connection Calculus, shows that our approach exhibits unparalleled performance against competing state-of-the-art approaches for checking the satisfiability of such constraint networks.

Su, G, Chen, T, Feng, Y, Rosenblum, DS & Thiagarajan, PS 2016, 'An iterative decision-making scheme for markov decision processes and its application to self-adaptive systems', Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Fundamental Approaches to Software Engineering, Springer, Eindhoven, The Netherlands, pp. 269-286.
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© Springer-Verlag Berlin Heidelberg 2016.Software is often governed by and thus adapts to phenomena that occur at runtime. Unlike traditional decision problems, where a decision-making model is determined for reasoning, the adaptation logic of such software is concerned with empirical data and is subject to practical constraints. We present an Iterative Decision-Making Scheme (IDMS) that infers both point and interval estimates for the undetermined transition probabilities in a Markov Decision Process (MDP) based on sampled data, and iteratively computes a confidently optimal scheduler from a given finite subset of schedulers. The most important feature of IDMS is the flexibility for adjusting the criterion of confident optimality and the sample size within the iteration, leading to a tradeoff between accuracy, data usage and computational overhead. We apply IDMS to an existing self-adaptation framework Rainbow and conduct a case study using a Rainbow system to demonstrate the flexibility of IDMS.

Sutter, D, Tomamichel, M & Harrow, AW 2016, 'Strengthened monotonicity of relative entropy via pinched Petz recovery map', Proceedings IEEE International Symposium on Information Theory (ISIT 2016), IEEE, Barcelona, pp. 760-764.
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Suwanwiwat, H, Pal, U & Blumenstein, M 2016, 'An Automatic Off-Line Short Answer Assessment System Using Novel Hybrid Features', 2016 International Conference on Digital Image Computing: Techniques and Applications, DICTA 2016, Digital Image Computing Techniques and Applications, IEEE, Gold Coast, Queensland, Australia.
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To date, paper-based examinations are still in use worldwide on all levels of education levels (e.g. secondary, tertiary levels). However, literature regarding off-line automatic assessment systems employing off-line handwriting recognition is not numerous. This paper proposes an off-line automatic assessment system employing a hybrid feature extraction technique - a newly proposed Modified Direction and Gaussian Grid Feature (MDGGF), along with its enhanced technique. In this study other original feature extraction techniques, together with their enhanced features, were also used for feature extraction technique efficiency comparison purposes. Classifiers, namely artificial neural networks and support vector machines, were selected to be employed in the experiments. Two types of datasets were employed in the experiment for both feature extraction technique accuracy and efficiency comparisons. The best correctly recognised rate of 98.33% with 100% accuracy was obtained when employing the proposed MDGGF to the off-line automatic assessment system.

Tomamichel, M & Hayashi, M 2016, 'Operational interpretation of Rényi conditional mutual information via composite hypothesis testing against Markov distributions', Proceedings IEEE International Symposium on Information Theory (ISIT 2016), IEEE International Symposium on Information Theory, IEEE, Barcelona, Spain, pp. 585-589.
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We revisit the problem of asymmetric binary hypothesis testing against a composite alternative hypothesis. We introduce a general framework to treat such problems when the alternative hypothesis adheres to certain axioms. In this case we find the threshold rate, the optimal error and strong converse exponents (at large deviations from the threshold) and the second-order asymptotics (at small deviations from the threshold). We apply our results to find operational interpretations of Rényi information measures. In particular, in case the alternative hypothesis consists of certain tripartite distributions satisfying the Markov property, we find that the optimal exponents are determined by the Rényi conditional mutual information

Wang, B, Gao, Y, Sun, C, Blumenstein, M & La Salle, J 2016, 'A Local Scale Selection Scheme for Multiscale Area Integral Invariants', 2016 International Conference on Digital Image Computing: Techniques and Applications, DICTA 2016, Digital Image Computing Techniques and Applications, IEEE, Gold Coast, QLD, Australia.
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© 2016 IEEE.Area integral invariant (AII) is a functional obtained by performing integral operations on the closed planar contour of a shape via the convolution with disc kernels. This shape descriptor is insensitive to noise and robust with respect to occlusions. AII intrinsically introduces the notion of scale using the size of kernel radius. However how to select an optimal scale remains unresolved. In this paper, we propose a local scale selection scheme for generating multiscale area integral invariants. For the same scale level, the disc kernel size is not fixed and varies with the contour point where the disc is centered. This scheme also provides a scale assignment for emphasising the features extraction at finer scales. The strong discriminative power of the multiscale area integral invariant derived from the proposed scale selection scheme has been validated through experiments on very challenging leaf image retrievals.

Wang, X & Duan, R 2016, 'A semidefinite programming upper bound of quantum capacity', IEEE International Symposium on Information Theory - Proceedings, IEEE International Symposium on Information Theory, IEEE, Barcelona, Spain, pp. 1690-1694.
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© 2016 IEEE.Recently the power of positive partial transpose preserving (PPTp) and no-signalling (NS) codes in quantum communication has been studied. We continue with this line of research and show that the NS/PPTp/NS∩PPTp codes assisted zero-error quantum capacity depends only on the non-commutative bipartite graph of the channel and the one-shot case can be computed efficiently by semidefinite programming (SDP). As an example, the activated PPTp codes assisted zero-error quantum capacity is carefully studied. We then present a general SDP upper bound QΓ of quantum capacity and show it is always smaller than or equal to the 'Partial transposition bound' introduced by Holevo and Werner, and the inequality could be strict. This upper bound is found to be additive, and thus is an upper bound of the potential PPTp assisted quantum capacity as well. We further demonstrate that QΓ is strictly better than several previously known upper bounds for an explicit class of quantum channels. Finally, we show that QΓ can be used to bound the super-activation of quantum capacity.

Wang, X & Duan, R 2016, 'On the quantum no-signalling assisted zero-error classical simulation cost of non-commutative bipartite graphs', IEEE International Symposium on Information Theory - Proceedings, IEEE International Symposium on Information Theory, IEEE, Barcelona, Spain, pp. 2244-2248.
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© 2016 IEEE.Using one channel to simulate another exactly with the aid of quantum no-signalling correlations has been studied recently. The one-shot no-signalling assisted classical zero-error simulation cost of non-commutative bipartite graphs has been formulated as semidefinite programms [Duan and Winter, IEEE Trans. Inf. Theory 62, 891 (2016)]. Before our work, it was unknown whether the one-shot (or asymptotic) no-signalling assisted zero-error classical simulation cost for general non-commutative graphs is multiplicative (resp. additive) or not. In this paper we address these issues and give a general sufficient condition for the multiplicativity of the one-shot simulation cost and the additivity of the asymptotic simulation cost of non-commutative bipartite graphs, which include all known cases such as extremal graphs and classical-quantum graphs. Applying this condition, we exhibit a large class of so-called cheapest-full-rank graphs whose asymptotic zero-error simulation cost is given by the one-shot simulation cost. Finally, we disprove the multiplicativity of one-shot simulation cost by explicitly constructing a special class of qubit-qutrit non-commutative bipartite graphs.

Xu, J, Shivakumara, P, Lu, T, Tan, CL & Blumenstein, M 2015, 'Text detection in born-digital images by mass estimation', Proceedings - 3rd IAPR Asian Conference on Pattern Recognition, ACPR 2015, IAPR Asian Conference on Pattern Recognition (ACPR), IEEE, Kuala Lumpur, Malaysia, pp. 690-694.
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© 2015 IEEE.There is a need for effective web-document understanding due to the explosive progress of internet and network technologies. In this paper, we propose a new method for text detection in born-digital images by introducing a mass estimation concept. We propose to explore super-pixel information of different color channels to identify text atoms in images. The proposed method uses similarity graphs and spectral clustering to identify candidate text regions. We propose a new idea of mapping Gabor responses of a candidate text region to a spatial circle to study the spatial coherency of pixels. We introduce a mass estimation concept to identify text candidates from the pixel distribution in a spatial circle. The linear linkage graphs help in grouping text candidates to obtain full text lines. The same Gabor responses are used as features to eliminate false positives with an SVM classifier. We evaluate the proposed method for the testing on standard datasets, such as ICDAR 2013 (challenge-1) and the Situ et al. dataset. Experimental results on both the datasets show that the proposed method outperforms the existing methods.

Rohde, P, Berry, DW, Motes, KR & Dowling, JP 2016, A Quantum Optics Argument for the #P-hardness of a Class of Multidimensional Integrals, https://arxiv.org/abs/1607.04960.

Ferrie, C & Blume-Kohout, R 2016, 'Bayes estimator for multinomial parameters and Bhattacharyya distances'.
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We derive the Bayes estimator for the parameters of a multinomial distribution under two loss functions ($1-B$ and $1-B^2$) that are based on the Bhattacharyya coefficient $B(\vec{p},\vec{q}) = \sum{\sqrt{p_kq_k}}$. We formulate a non-commutative generalization relevant to quantum probability theory as an open problem. As an example application, we use our solution to find minimax estimators for a binomial parameter under Bhattacharyya loss ($1-B^2$).

Lai, C-Y & Duan, R 2016, 'On the One-Shot Zero-Error Classical Capacity of Classical-Quantum Channels Assisted by Quantum Non-signalling Correlations'.
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Duan and Winter studied the one-shot zero-error classical capacity of a quantum channel assisted by quantum non-signalling correlations, and formulated this problem as a semidefinite program depending only on the Kraus operator space of the channel. For the class of classical-quantum channels, they showed that the asymptotic zero-error classical capacity assisted by quantum non-signalling correlations, minimized over all classical-quantum channels with a confusability graph $G$, is exactly $\log \vartheta(G)$, where $\vartheta(G)$ is the celebrated Lov\'{a}sz theta function. In this paper, we show that the same result holds in the one-shot setting for a class of circulant graphs defined by equal-sized cyclotomic cosets, which include the cycle graphs of odd length, the Paley graphs of prime vertices, and the cubit residue graphs of prime vertices. Examples of other graphs are also discussed. This endows the Lov\'{a}sz $\theta$ function with a more straightforward operational meaning.

Liu, T, Li, Y, Wang, S, Ying, M & Zhan, N 2016, 'A Theorem Prover for Quantum Hoare Logic and Its Applications.'.
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