PRA: Quantum information

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Recently published articles in Phys. Rev. A in the Table of Content section "Quantum information"
Updated: 14 min 5 sec ago

Experimental study on all-fiber-based unidimensional continuous-variable quantum key distribution

6 hours 59 min ago

Author(s): Xuyang Wang, Wenyuan Liu, Pu Wang, and Yongmin Li

We experimentally demonstrated an all-fiber-based unidimensional continuous-variable quantum key distribution (CV QKD) protocol and analyzed its security under collective attack in realistic conditions. A pulsed balanced homodyne detector, which could not be accessed by eavesdroppers, with phase-ins...

[Phys. Rev. A 95, 062330] Published Mon Jun 26, 2017

Categories: Journals, Physics

Genuine N-partite entanglement without N-partite correlation functions

6 hours 59 min ago

Author(s): Minh Cong Tran, Margherita Zuppardo, Anna de Rosier, Lukas Knips, Wiesław Laskowski, Tomasz Paterek, and Harald Weinfurter

A generalized and thorough investigation of entanglement without correlations is presented. The study sheds light on the different properties of systems composed of an even or odd number of qubits, and might help to construct computable measures of multipartite correlation.

[Phys. Rev. A 95, 062331] Published Mon Jun 26, 2017

Categories: Journals, Physics

Construction of optimal resources for concatenated quantum protocols

6 hours 59 min ago

Author(s): A. Pirker, J. Wallnöfer, H. J. Briegel, and W. Dür

We consider the explicit construction of resource states for measurement-based quantum information processing. We concentrate on special-purpose resource states that are capable to perform a certain operation or task, where we consider unitary Clifford circuits as well as non-trace-preserving comple...

[Phys. Rev. A 95, 062332] Published Mon Jun 26, 2017

Categories: Journals, Physics

Quantum key distribution protocol based on contextuality monogamy

6 hours 59 min ago

Author(s): Jaskaran Singh, Kishor Bharti, and Arvind

The security of quantum key distribution (QKD) protocols hinges upon features of physical systems that are uniquely quantum in nature. We explore the role of quantumness, as qualified by quantum contextuality, in a QKD scheme. A QKD protocol based on the Klyachko-Can-Binicioğlu-Shumovsky (KCBS) cont...

[Phys. Rev. A 95, 062333] Published Mon Jun 26, 2017

Categories: Journals, Physics

Quantum money with nearly optimal error tolerance

6 hours 59 min ago

Author(s): Ryan Amiri and Juan Miguel Arrazola

We present a family of quantum money schemes with classical verification which display a number of benefits over previous proposals. Our schemes are based on hidden matching quantum retrieval games and they tolerate noise up to 23%, which we conjecture reaches 25% asymptotically as the dimension of ...

[Phys. Rev. A 95, 062334] Published Mon Jun 26, 2017

Categories: Journals, Physics

Long-time efficacy of the surface code in the presence of a super-Ohmic environment

Fri, 2017-06-23 16:00

Author(s): D. A. López-Delgado, E. Novais, E. R. Mucciolo, and A. O. Caldeira

We study the long-time evolution of a quantum memory coupled to a bosonic environment on which quantum error correction (QEC) is performed using the surface code. The memory's evolution encompasses N QEC cycles, each of them yielding a nonerror syndrome. This assumption makes our analysis independen...

[Phys. Rev. A 95, 062328] Published Fri Jun 23, 2017

Categories: Journals, Physics

Monogamy inequality for entanglement and local contextuality

Fri, 2017-06-23 16:00

Author(s): S. Camalet

We derive a monogamy inequality for entanglement and local contextuality, for any finite bipartite system. It essentially results from the relations between the entropy of a local state and the entanglement of the global state, and between the purity of a state, in the sense of majorization, and its...

[Phys. Rev. A 95, 062329] Published Fri Jun 23, 2017

Categories: Journals, Physics

Resource theory of coherence: Beyond states

Tue, 2017-06-20 16:00

Author(s): Khaled Ben Dana, María García Díaz, Mohamed Mejatty, and Andreas Winter

We generalize the recently proposed resource theory of coherence (or superposition) [T. Baumgratz et al., Phys. Rev. Lett. 113, 140401 (2014); A. Winter and D. Yang, Phys. Rev. Lett. 116, 120404 (2016)] to the setting where not just the free (“incoherent”) resources, but also the manipulated object...

[Phys. Rev. A 95, 062327] Published Tue Jun 20, 2017

Categories: Journals, Physics

Entanglement, coherence, and redistribution of quantum resources in double spontaneous down-conversion processes

Fri, 2017-06-16 16:00

Author(s): David Edward Bruschi, Carlos Sabín, and Gheorghe Sorin Paraoanu

We study the properties of bisqueezed tripartite Gaussian states created by two spontaneous parametric down-conversion processes that share a common idler. We give a complete description of the quantum correlations across all partitions, as well as of the genuine multipartite entanglement, obtaining...

[Phys. Rev. A 95, 062324] Published Fri Jun 16, 2017

Categories: Journals, Physics

Robust quantum gates for stochastic time-varying noise

Fri, 2017-06-16 16:00

Author(s): Chia-Hsien Huang and Hsi-Sheng Goan

How to effectively construct robust quantum gates for time-varying noise is a very important but still outstanding problem. Here we develop a systematic method to find pulses for quantum gate operations robust against both low- and high-frequency (comparable to the qubit transition frequency) stocha...

[Phys. Rev. A 95, 062325] Published Fri Jun 16, 2017

Categories: Journals, Physics

Quantum and random walks as universal generators of probability distributions

Fri, 2017-06-16 16:00

Author(s): Miquel Montero

Quantum walks and random walks bear similarities and divergences. One of the most remarkable disparities affects the probability of finding the particle at a given location: typically, almost a flat function in the first case and a bell-shaped one in the second case. Here I show how one can impose a...

[Phys. Rev. A 95, 062326] Published Fri Jun 16, 2017

Categories: Journals, Physics

Self-testing of binary observables based on commutation

Thu, 2017-06-15 16:00

Author(s): Jędrzej Kaniewski

We consider the problem of certifying binary observables based on a Bell inequality violation alone, a task known as self-testing of measurements. We introduce a family of commutation-based measures, which encode all the distinct arrangements of two projective observables on a qubit. These quantitie...

[Phys. Rev. A 95, 062323] Published Thu Jun 15, 2017

Categories: Journals, Physics

Nonadditivity of Rains' bound for distillable entanglement

Wed, 2017-06-14 16:00

Author(s): Xin Wang and Runyao Duan

Rains' bound is arguably the best known upper bound of the distillable entanglement by operations completely preserving positivity of partial transpose (PPT) and was conjectured to be additive and coincide with the asymptotic relative entropy of entanglement. We disprove both conjectures by explicit...

[Phys. Rev. A 95, 062322] Published Wed Jun 14, 2017

Categories: Journals, Physics

Bipartite entanglement in fermion systems

Tue, 2017-06-13 16:00

Author(s): N. Gigena and R. Rossignoli

We discuss the relation between fermion entanglement and bipartite entanglement. We first show that an exact correspondence between them arises when the states are constrained to have a definite local number parity. Moreover, for arbitrary states in a four-dimensional single-particle Hilbert space, ...

[Phys. Rev. A 95, 062320] Published Tue Jun 13, 2017

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Achieving high-fidelity single-qubit gates in a strongly driven silicon-quantum-dot hybrid qubit

Tue, 2017-06-13 16:00

Author(s): Yuan-Chi Yang, S. N. Coppersmith, and Mark Friesen

Performing qubit gate operations as quickly as possible can be important to minimize the effects of decoherence. For resonant gates, this requires applying a strong ac drive. However, strong driving can present control challenges by causing leakage to levels that lie outside the qubit subspace. Stro...

[Phys. Rev. A 95, 062321] Published Tue Jun 13, 2017

Categories: Journals, Physics

General scheme for preparation of different topological states on cluster states

Mon, 2017-06-12 16:00

Author(s): Mohammad Hossein Zarei

Although it is well-known that all quantum states can be produced by single-qubit measurements on the cluster states, it is not a simple task to explicitly find which measurement patterns on the cluster states can generate different quantum states. In this paper, we introduce a general scheme to fin...

[Phys. Rev. A 95, 062316] Published Mon Jun 12, 2017

Categories: Journals, Physics

Witnessing nonclassical correlations via a single-shot experiment on an ensemble of spins using nuclear magnetic resonance

Mon, 2017-06-12 16:00

Author(s): Amandeep Singh, Arvind, and Kavita Dorai

A bipartite quantum system in a mixed state can exhibit nonclassical correlations which can go beyond quantum entanglement. While quantum discord is the standard measure of quantifying such general quantum correlations, the nonclassicality can be determined by simpler means via the measurement of wi...

[Phys. Rev. A 95, 062318] Published Mon Jun 12, 2017

Categories: Journals, Physics

Near-optimal quantum circuit for Grover's unstructured search using a transverse field

Mon, 2017-06-12 16:00

Author(s): Zhang Jiang, Eleanor G. Rieffel, and Zhihui Wang

Inspired by a class of algorithms proposed by Farhi et al. (arXiv:1411.4028), namely, the quantum approximate optimization algorithm (QAOA), we present a circuit-based quantum algorithm to search for a needle in a haystack, obtaining the same quadratic speedup achieved by Grover's original algorith...

[Phys. Rev. A 95, 062317] Published Mon Jun 12, 2017

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Optimal shortcut approach based on an easily obtained intermediate Hamiltonian

Mon, 2017-06-12 16:00

Author(s): Ye-Hong Chen, Zhi-Cheng Shi, Jie Song, Yan Xia, and Shi-Biao Zheng

We present a general approach to speed up the adiabatic process without adding the traditional counterdiabatic driving Hamiltonian. The strategy is to design an easy-to-get intermediate Hamiltonian to connect the original Hamiltonian and final transitionless Hamiltonian. With a final transitionless ...

[Phys. Rev. A 95, 062319] Published Mon Jun 12, 2017

Categories: Journals, Physics

Experimental bilocality violation without shared reference frames

Fri, 2017-06-09 16:00

Author(s): Francesco Andreoli, Gonzalo Carvacho, Luca Santodonato, Marco Bentivegna, Rafael Chaves, and Fabio Sciarrino

Nonclassical correlations arising in complex quantum networks are attracting growing interest, both from a fundamental perspective and for potential applications in information processing. In particular, in an entanglement swapping scenario a new kind of correlations arise, the so-called nonbilocal ...

[Phys. Rev. A 95, 062315] Published Fri Jun 09, 2017

Categories: Journals, Physics