PRA: Quantum information

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Recently published articles in Phys. Rev. A in the Table of Content section "Quantum information"
Updated: 6 min 3 sec ago

Algorithm for the solution of the Dirac equation on digital quantum computers

Fri, 2017-04-28 16:00

Author(s): François Fillion-Gourdeau, Steve MacLean, and Raymond Laflamme

A quantum algorithm that solves the time-dependent Dirac equation on a digital quantum computer is developed and analyzed. The time evolution is performed by an operator-splitting decomposition technique that allows for a mapping of the Dirac operator to a quantum walk supplemented by unitary rotati…


[Phys. Rev. A 95, 042343] Published Fri Apr 28, 2017

Categories: Journals, Physics

Device-independent quantum private query

Fri, 2017-04-28 16:00

Author(s): Arpita Maitra, Goutam Paul, and Sarbani Roy

In quantum private query (QPQ), a client obtains values corresponding to his or her query only, and nothing else from the server, and the server does not get any information about the queries. V. Giovannetti et al. [Phys. Rev. Lett. 100, 230502 (2008)] gave the first QPQ protocol and since then qui…


[Phys. Rev. A 95, 042344] Published Fri Apr 28, 2017

Categories: Journals, Physics

Measuring the Berry phase in a superconducting phase qubit by a shortcut to adiabaticity

Fri, 2017-04-28 16:00

Author(s): Zhenxing Zhang, Tenghui Wang, Liang Xiang, Jiadong Yao, Jianlan Wu, and Yi Yin

A scheme for fast measurements of geometrical phases in a superconducting qubit platform is demonstrated. The result might boost developments in quantum computation.


[Phys. Rev. A 95, 042345] Published Fri Apr 28, 2017

Categories: Journals, Physics

Protecting entanglement from finite-temperature thermal noise via weak measurement and quantum measurement reversal

Thu, 2017-04-27 16:00

Author(s): Wen-Jie Zou, Yu-Huai Li, Shu-Chao Wang, Yuan Cao, Ji-Gang Ren, Juan Yin, Cheng-Zhi Peng, Xiang-Bin Wang, and Jian-Wei Pan

In practical applications, quantum systems work in a finite-temperature environment. Quantum entanglement is inevitably destroyed by the thermal noise. Here we experimentally demonstrate the protection of entanglement on the platform of linear optics. The finite-temperature thermal noise is describe…


[Phys. Rev. A 95, 042342] Published Thu Apr 27, 2017

Categories: Journals, Physics

Surface code fidelity at finite temperatures

Wed, 2017-04-26 16:00

Author(s): E. Novais, A. J. Stanforth, and Eduardo R. Mucciolo

We study the dependence of the fidelity of the surface code in the presence of a single finite-temperature massless bosonic environment after a quantum error correction cycle. The three standard types of environment are considered: super-Ohmic, Ohmic, and sub-Ohmic. Our results show that, for regime…


[Phys. Rev. A 95, 042339] Published Wed Apr 26, 2017

Categories: Journals, Physics

Measurement-device-independent entanglement and randomness estimation in quantum networks

Wed, 2017-04-26 16:00

Author(s): Ivan Šupić, Paul Skrzypczyk, and Daniel Cavalcanti

Detection of entanglement in quantum networks consisting of many parties is one of the important steps toward building quantum communication and computation networks. We consider a scenario where the measurement devices used for this certification are uncharacterized. In this case, it is well known …


[Phys. Rev. A 95, 042340] Published Wed Apr 26, 2017

Categories: Journals, Physics

Quantum search on the two-dimensional lattice using the staggered model with Hamiltonians

Wed, 2017-04-26 16:00

Author(s): R. Portugal and T. D. Fernandes

Quantum search on the two-dimensional lattice with one marked vertex and cyclic boundary conditions is an important problem in the context of quantum algorithms with an interesting unfolding. It avails to test the ability of quantum walk models to provide efficient algorithms from the theoretical si…


[Phys. Rev. A 95, 042341] Published Wed Apr 26, 2017

Categories: Journals, Physics

Power of one nonclean qubit

Tue, 2017-04-25 16:00

Author(s): Tomoyuki Morimae, Keisuke Fujii, and Harumichi Nishimura

The one-clean qubit model (or the DQC1 model) is a restricted model of quantum computing where only a single qubit of the initial state is pure and others are maximally mixed. Although the model is not universal, it can efficiently solve several problems whose classical efficient solutions are not k…


[Phys. Rev. A 95, 042336] Published Tue Apr 25, 2017

Categories: Journals, Physics

Quantum coherence via skew information and its polygamy

Tue, 2017-04-25 16:00

Author(s): Chang-shui Yu

Quantifying coherence is a key task in both quantum-mechanical theory and practical applications. Here, a reliable quantum coherence measure is presented by utilizing the quantum skew information of the state of interest subject to a certain broken observable. This coherence measure is proven to ful…


[Phys. Rev. A 95, 042337] Published Tue Apr 25, 2017

Categories: Journals, Physics

Experimental measurement-device-independent quantum digital signatures over a metropolitan network

Tue, 2017-04-25 16:00

Author(s): Hua-Lei Yin, Wei-Long Wang, Yan-Lin Tang, Qi Zhao, Hui Liu, Xiang-Xiang Sun, Wei-Jun Zhang, Hao Li, Ittoop Vergheese Puthoor, Li-Xing You, Erika Andersson, Zhen Wang, Yang Liu, Xiao Jiang, Xiongfeng Ma, Qiang Zhang, Marcos Curty, Teng-Yun Chen, and Jian-Wei Pan

Quantum digital signatures (QDSs) provide a means for signing electronic communications with information-theoretic security. However, all previous demonstrations of quantum digital signatures assume trusted measurement devices. This renders them vulnerable against detector side-channel attacks, just…


[Phys. Rev. A 95, 042338] Published Tue Apr 25, 2017

Categories: Journals, Physics

Robust quantum entanglement generation and generation-plus-storage protocols with spin chains

Mon, 2017-04-24 16:00

Author(s): Marta P. Estarellas, Irene D'Amico, and Timothy P. Spiller

Reliable quantum communication and/or processing links between modules are a necessary building block for various quantum processing architectures. Here we consider a spin-chain system with alternating strength couplings and containing three defects, which impose three domain walls between topologic…


[Phys. Rev. A 95, 042335] Published Mon Apr 24, 2017

Categories: Journals, Physics

Superconducting quantum simulator for topological order and the toric code

Fri, 2017-04-21 16:00

Author(s): Mahdi Sameti, Anton Potočnik, Dan E. Browne, Andreas Wallraff, and Michael J. Hartmann

Topological order is now being established as a central criterion for characterizing and classifying ground states of condensed matter systems and complements categorizations based on symmetries. Fractional quantum Hall systems and quantum spin liquids are receiving substantial interest because of t…


[Phys. Rev. A 95, 042330] Published Fri Apr 21, 2017

Categories: Journals, Physics

Efficient state initialization by a quantum spectral filtering algorithm

Fri, 2017-04-21 16:00

Author(s): François Fillion-Gourdeau, Steve MacLean, and Raymond Laflamme

An algorithm that initializes a quantum register to a state with a specified energy range is given, corresponding to a quantum implementation of the celebrated Feit-Fleck method. This is performed by introducing a nondeterministic quantum implementation of a standard spectral filtering procedure com…


[Phys. Rev. A 95, 042331] Published Fri Apr 21, 2017

Categories: Journals, Physics

Hard decoding algorithm for optimizing thresholds under general Markovian noise

Fri, 2017-04-21 16:00

Author(s): Christopher Chamberland, Joel Wallman, Stefanie Beale, and Raymond Laflamme

Quantum error correction is instrumental in protecting quantum systems from noise in quantum computing and communication settings. Pauli channels can be efficiently simulated and threshold values for Pauli error rates under a variety of error-correcting codes have been obtained. However, realistic q…


[Phys. Rev. A 95, 042332] Published Fri Apr 21, 2017

Categories: Journals, Physics

Quantifying entanglement properties of qudit mixed states with incomplete permutation symmetry

Fri, 2017-04-21 16:00

Author(s): Artur Barasiński and Mateusz Nowotarski

The characterization of entanglement properties in mixed states is important from both a theoretical and a practical point of view. While the estimation of entanglement of bipartite pure states is well established, for mixed states it is a considerably much harder task. The key elements of the mixed…


[Phys. Rev. A 95, 042333] Published Fri Apr 21, 2017

Categories: Journals, Physics

Rényi formulation of entanglement criteria for continuous variables

Fri, 2017-04-21 16:00

Author(s): Alexey E. Rastegin

Entanglement criteria for an n-partite quantum system with continuous variables are formulated in terms of Rényi entropies. Rényi entropies are widely used as a good information measure due to many nice properties. Derived entanglement criteria are based on several mathematical results such as the H…


[Phys. Rev. A 95, 042334] Published Fri Apr 21, 2017

Categories: Journals, Physics

Accessible coherence and coherence distribution

Thu, 2017-04-20 16:00

Author(s): Teng Ma, Ming-Jing Zhao, Hai-Jun Zhang, Shao-Ming Fei, and Gui-Lu Long

The definition of accessible coherence is proposed. Through local measurement on the other subsystem and one-way classical communication, a subsystem can access more coherence than the coherence of its density matrix. Based on the local accessible coherence, the part that cannot be locally accessed …


[Phys. Rev. A 95, 042328] Published Thu Apr 20, 2017

Categories: Journals, Physics

Experimental demonstration of loop state-preparation-and-measurement tomography

Thu, 2017-04-20 16:00

Author(s): A. F. McCormick, S. J. van Enk, and M. Beck

We have performed an experiment demonstrating that loop state-preparation-and-measurement tomography [Jackson and van Enk, Phys. Rev. A 92, 042312 (2015)] is capable of detecting correlated errors between the preparation and the measurement of a quantum system. Specifically, we have prepared pure an…


[Phys. Rev. A 95, 042329] Published Thu Apr 20, 2017

Categories: Journals, Physics

Scaling of entanglement during the quantum phase transition for Ising spin systems on triangular and Sierpiński fractal lattices

Wed, 2017-04-19 16:00

Author(s): Yu-Liang Xu, Xiang-Mu Kong, Zhong-Qiang Liu, and Chuan-Cun Yin

Adopting concurrence as entanglement measure, we study entanglement and quantum phase transition of the Ising spin systems on the triangular lattice and Sierpiński fractal lattices by using the quantum renormalization-group method. It is found that the ground-state entanglement between two spins (or…


[Phys. Rev. A 95, 042327] Published Wed Apr 19, 2017

Categories: Journals, Physics

Measuring higher-dimensional entanglement

Tue, 2017-04-18 16:00

Author(s): Chandan Datta, Pankaj Agrawal, and Sujit K. Choudhary

We study local-realistic inequalities, Bell-type inequalities, for bipartite pure states of finite dimensional quantum systems—qudits. There are a number of proposed Bell-type inequalities for such systems. Our interest is in relating the value of the Bell-type inequality function with a measure of …


[Phys. Rev. A 95, 042323] Published Tue Apr 18, 2017

Categories: Journals, Physics