PRA: Quantum information

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Recently published articles in Phys. Rev. A in the Table of Content section "Quantum information"
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Chiral spin currents in a trapped-ion quantum simulator using Floquet engineering

Fri, 2018-01-19 11:00

Author(s): Tobias Graß, Alessio Celi, Guido Pagano, and Maciej Lewenstein

The most typical ingredient of topologically protected quantum states is magnetic fluxes. In a system of spins, complex-valued interaction parameters give rise to a flux, if their phases do not add up to zero along a closed loop. Here we apply periodic driving, a powerful tool for quantum engineerin...


[Phys. Rev. A 97, 010302(R)] Published Fri Jan 19, 2018

Categories: Journals, Physics

Protecting the entanglement of twisted photons by adaptive optics

Fri, 2018-01-19 11:00

Author(s): Nina Leonhard, Giacomo Sorelli, Vyacheslav N. Shatokhin, Claudia Reinlein, and Andreas Buchleitner

Entanglement degradation of orbital-angular-momentum modes can be prevented using adaptive optics. The results prove the possibility of significantly reducing the crosstalk of modes, thereby making entanglement available even under moderate atmospheric turbulence conditions.


[Phys. Rev. A 97, 012321] Published Fri Jan 19, 2018

Categories: Journals, Physics

Ultimate entanglement robustness of two-qubit states against general local noises

Fri, 2018-01-19 11:00

Author(s): Sergey N. Filippov, Vladimir V. Frizen, and Daria V. Kolobova

We study the problem of optimal preparation of a bipartite entangled state, which remains entangled the longest time under action of local qubit noises. We show that for unital noises, such a state is always maximally entangled, whereas for nonunital noises, it is not. We develop a decomposition tec...


[Phys. Rev. A 97, 012322] Published Fri Jan 19, 2018

Categories: Journals, Physics

Qudit hypergraph states and their properties

Fri, 2018-01-19 11:00

Author(s): Fei-Lei Xiong, Yi-Zheng Zhen, Wen-Fei Cao, Kai Chen, and Zeng-Bing Chen

Hypergraph states, a generalization of graph states, constitute a large class of quantum states with intriguing nonlocal properties, and they have promising applications in quantum information science and technology. In this paper, we study some features of an independently proposed generalization o...


[Phys. Rev. A 97, 012323] Published Fri Jan 19, 2018

Categories: Journals, Physics

Quantum-key-distribution protocol with pseudorandom bases

Tue, 2018-01-16 11:00

Author(s): A. S. Trushechkin, P. A. Tregubov, E. O. Kiktenko, Y. V. Kurochkin, and A. K. Fedorov

Quantum key distribution (QKD) offers a way for establishing information-theoretical secure communications. An important part of QKD technology is a high-quality random number generator for the quantum-state preparation and for post-processing procedures. In this work, we consider a class of prepare...


[Phys. Rev. A 97, 012311] Published Tue Jan 16, 2018

Categories: Journals, Physics

Generating maximally-path-entangled number states in two spin ensembles coupled to a superconducting flux qubit

Tue, 2018-01-16 11:00

Author(s): Yusef Maleki and Aleksei M. Zheltikov

An ensemble of nitrogen-vacancy (NV) centers coupled to a circuit QED device is shown to enable an efficient, high-fidelity generation of high-N00N states. Instead of first creating entanglement and then increasing the number of entangled particles N, our source of high-N00N states first prepares a ...


[Phys. Rev. A 97, 012312] Published Tue Jan 16, 2018

Categories: Journals, Physics

One-sided measurement-device-independent quantum key distribution

Tue, 2018-01-16 11:00

Author(s): Wen-Fei Cao, Yi-Zheng Zhen, Yu-Lin Zheng, Li Li, Zeng-Bing Chen, Nai-Le Liu, and Kai Chen

Measurement-device-independent quantum key distribution (MDI-QKD) protocol was proposed to remove all the detector side channel attacks, while its security relies on the trusted encoding systems. Here we propose a one-sided MDI-QKD (1SMDI-QKD) protocol, which enjoys detection loophole-free advantage...


[Phys. Rev. A 97, 012313] Published Tue Jan 16, 2018

Categories: Journals, Physics

Device-independent certification of two bits of randomness from one entangled bit and Gisin's elegant Bell inequality

Tue, 2018-01-16 11:00

Author(s): Ole Andersson, Piotr Badziąg, Irina Dumitru, and Adán Cabello

We prove that as conjectured by Acín et al. [Phys. Rev. A 93, 040102(R) (2016)], two bits of randomness can be certified in a device-independent way from one bit of entanglement using the maximal quantum violation of Gisin's elegant Bell inequality. This suggests a surprising connection between maxi...


[Phys. Rev. A 97, 012314] Published Tue Jan 16, 2018

Categories: Journals, Physics

Beating the classical limits of information transmission using a quantum decoder

Tue, 2018-01-16 11:00

Author(s): Robert J. Chapman, Akib Karim, Zixin Huang, Steven T. Flammia, Marco Tomamichel, and Alberto Peruzzo

Encoding schemes and error-correcting codes are widely used in information technology to improve the reliability of data transmission over real-world communication channels. Quantum information protocols can further enhance the performance in data transmission by encoding a message in quantum states...


[Phys. Rev. A 97, 012315] Published Tue Jan 16, 2018

Categories: Journals, Physics

Emergence of entanglement with temperature and time in factorization-surface states

Tue, 2018-01-16 11:00

Author(s): Titas Chanda, Tamoghna Das, Debasis Sadhukhan, Amit Kumar Pal, Aditi Sen(De), and Ujjwal Sen

There exist zero-temperature states in quantum many-body systems that are fully factorized, thereby possessing vanishing entanglement, and hence being of no use as resource in quantum information processing tasks. Such states can become useful for quantum protocols when the temperature of the system...


[Phys. Rev. A 97, 012316] Published Tue Jan 16, 2018

Categories: Journals, Physics

Passive state preparation in the Gaussian-modulated coherent-states quantum key distribution

Tue, 2018-01-16 11:00

Author(s): Bing Qi, Philip G. Evans, and Warren P. Grice

In the Gaussian-modulated coherent-states (GMCS) quantum key distribution (QKD) protocol, Alice prepares quantum states actively: For each transmission, Alice generates a pair of Gaussian-distributed random numbers, encodes them on a weak coherent pulse using optical amplitude and phase modulators, ...


[Phys. Rev. A 97, 012317] Published Tue Jan 16, 2018

Categories: Journals, Physics

Measurement-free implementations of small-scale surface codes for quantum-dot qubits

Tue, 2018-01-16 11:00

Author(s): H. Ekmel Ercan, Joydip Ghosh, Daniel Crow, Vickram N. Premakumar, Robert Joynt, Mark Friesen, and S. N. Coppersmith

The performance of quantum-error-correction schemes depends sensitively on the physical realizations of the qubits and the implementations of various operations. For example, in quantum-dot spin qubits, readout is typically much slower than gate operations, and conventional surface-code implementati...


[Phys. Rev. A 97, 012318] Published Tue Jan 16, 2018

Categories: Journals, Physics

High resource of azimuthal entanglement in terms of Cartesian variables of noncollinear biphotons

Tue, 2018-01-16 11:00

Author(s): M. V. Fedorov

Single-particle and coincidence distributions of photons are analyzed for the noncollinear frequency-degenerate type-I regime of spontaneous parametric down-conversion. Noncollinearity itself is shown to provide a new mechanism of strong broadening of the single-particle distributions in Cartesian c...


[Phys. Rev. A 97, 012319] Published Tue Jan 16, 2018

Categories: Journals, Physics

Optimal entangling operations between deterministic blocks of qubits encoded into single photons

Tue, 2018-01-16 11:00

Author(s): Jake A. Smith and Lev Kaplan

Here, we numerically simulate probabilistic elementary entangling operations between rail-encoded photons for the purpose of scalable universal quantum computation or communication. We propose grouping logical qubits into single-photon blocks wherein single-qubit rotations and the controlled-not (cn...


[Phys. Rev. A 97, 012320] Published Tue Jan 16, 2018

Categories: Journals, Physics

Quantum-enhanced sensing from hyperentanglement

Fri, 2018-01-12 11:00

Author(s): S. P. Walborn, A. H. Pimentel, L. Davidovich, and R. L. de Matos Filho

Hyperentanglement—simultaneous entanglement between multiple degrees of freedom of two or more systems—has been used to enhance quantum information tasks such as quantum communication and photonic quantum computing. Here we show that hyperentanglement can lead to increased quantum advantage in metro...


[Phys. Rev. A 97, 010301(R)] Published Fri Jan 12, 2018

Categories: Journals, Physics

Finding paths in tree graphs with a quantum walk

Fri, 2018-01-12 11:00

Author(s): Daniel Koch and Mark Hillery

We analyze the potential for different types of searches using the formalism of scattering random walks on quantum computers. Given a particular type of graph consisting of nodes and connections, a “tree maze,” we would like to find a selected final node as quickly as possible, faster than any class...


[Phys. Rev. A 97, 012308] Published Fri Jan 12, 2018

Categories: Journals, Physics

Analysis of coined quantum walks with renormalization

Fri, 2018-01-12 11:00

Author(s): Stefan Boettcher and Shanshan Li

We introduce a framework to analyze quantum algorithms with the renormalization group (RG). To this end, we present a detailed analysis of the real-space RG for discrete-time quantum walks on fractal networks and show how deep insights into the analytic structure as well as generic results about the...


[Phys. Rev. A 97, 012309] Published Fri Jan 12, 2018

Categories: Journals, Physics

Pilot-multiplexed continuous-variable quantum key distribution with a real local oscillator

Fri, 2018-01-12 11:00

Author(s): Tao Wang, Peng Huang, Yingming Zhou, Weiqi Liu, and Guihua Zeng

We propose a pilot-multiplexed continuous-variable quantum key distribution (CVQKD) scheme based on a local local oscillator (LLO). Our scheme utilizes time-multiplexing and polarization-multiplexing techniques to dramatically isolate the quantum signal from the pilot, employs two heterodyne detecto...


[Phys. Rev. A 97, 012310] Published Fri Jan 12, 2018

Categories: Journals, Physics

Entanglement and dynamical phase transition in a spin-orbit-coupled Bose-Einstein condensate

Thu, 2018-01-11 11:00

Author(s): F. X. Sun, W. Zhang, Q. Y. He, and Q. H. Gong

Characterizing quantum phase transitions through quantum correlations has been deeply developed for a long time, while the connections between dynamical phase transitions (DPTs) and quantum entanglement is not yet well understood. In this work, we show that the time-averaged two-mode entanglement in...


[Phys. Rev. A 97, 012307] Published Thu Jan 11, 2018

Categories: Journals, Physics

Gaussian intrinsic entanglement for states with partial minimum uncertainty

Wed, 2018-01-10 11:00

Author(s): Ladislav Mišta, Jr. and Klára Baksová

We develop a recently proposed theory of a quantifier of bipartite Gaussian entanglement called Gaussian intrinsic entanglement (GIE) [L. Mišta, Jr. and R. Tatham, Phys. Rev. Lett. 117, 240505 (2016)]. Gaussian intrinsic entanglement provides a compromise between computable and physically meaningful...


[Phys. Rev. A 97, 012305] Published Wed Jan 10, 2018

Categories: Journals, Physics