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PRA: Quantum information

Recently published articles in Phys. Rev. A in the Table of Content section "Quantum information"

Published: 2017-08-16T15:28:55-04:00


Probabilistic quantum teleportation via thermal entanglement


Author(s): Raphael Fortes and Gustavo Rigolin

We study the probabilistic (conditional) teleportation protocol when the entanglement needed for its implementation is given by thermal entanglement, i.e., when the entangled resource connecting Alice and Bob is an entangled mixed state described by the canonical ensemble density matrix. Specificall...

[Phys. Rev. A 96, 022315] Published Wed Aug 16, 2017

Quantum illumination for enhanced detection of Rayleigh-fading targets


Author(s): Quntao Zhuang, Zheshen Zhang, and Jeffrey H. Shapiro

Quantum illumination (QI) is an entanglement-enhanced sensing system whose performance advantage over a comparable classical system survives its usage in an entanglement-breaking scenario plagued by loss and noise. In particular, QI's error-probability exponent for discriminating between equally lik...

[Phys. Rev. A 96, 020302(R)] Published Tue Aug 15, 2017

Fast quantum state engineering via universal SU(2) transformation


Author(s): Bi-Hua Huang, Yi-Hao Kang, Ye-Hong Chen, Qi-Cheng Wu, Jie Song, and Yan Xia

We introduce a simple yet versatile protocol to inverse engineer the time-dependent Hamiltonian in two- and three-level systems. In the protocol, by utilizing a universal SU(2) transformation, a given speedup goal can be obtained with large freedom to select the control parameters. As an illustratio...

[Phys. Rev. A 96, 022314] Published Tue Aug 15, 2017

Linear feedback stabilization of a dispersively monitored qubit


Author(s): Taylor Lee Patti, Areeya Chantasri, Luis Pedro García-Pintos, Andrew N. Jordan, and Justin Dressel

The state of a continuously monitored qubit evolves stochastically, exhibiting competition between coherent Hamiltonian dynamics and diffusive partial collapse dynamics that follow the measurement record. We couple these distinct types of dynamics together by linearly feeding the collected record fo...

[Phys. Rev. A 96, 022311] Published Mon Aug 14, 2017

Optimal discrimination of single-qubit mixed states


Author(s): Graeme Weir, Stephen M. Barnett, and Sarah Croke

We consider the problem of minimum-error quantum state discrimination for single-qubit mixed states. We present a method which uses the Helstrom conditions constructively and analytically; this algebraic approach is complementary to existing geometric methods, and solves the problem for any number o...

[Phys. Rev. A 96, 022312] Published Mon Aug 14, 2017

Monogamy inequalities for certifiers of continuous-variable Einstein-Podolsky-Rosen entanglement without the assumption of Gaussianity


Author(s): L. Rosales-Zárate, R. Y. Teh, B. Opanchuk, and M. D. Reid

We consider three modes $A$, $B$, and $C$ and derive monogamy inequalities that constrain the distribution of bipartite continuous variable Einstein-Podolsky-Rosen entanglement amongst the three modes. The inequalities hold without the assumption of Gaussian states, and are based on measurements of ...

[Phys. Rev. A 96, 022313] Published Mon Aug 14, 2017

Secure alignment of coordinate systems using quantum correlation


Author(s): F. Rezazadeh, A. Mani, and V. Karimipour

We show that two parties far apart can use shared entangled states and classical communication to align their coordinate systems with a very high fidelity. Moreover, compared with previous methods proposed for such a task, i.e., sending parallel or antiparallel pairs or groups of spin states, our me...

[Phys. Rev. A 96, 022310] Published Fri Aug 11, 2017

Robust not gate by single-shot-shaped pulses: Demonstration of the efficiency of the pulses in rephasing atomic coherences


Author(s): Leo Van-Damme, Daniel Schraft, Genko T. Genov, Dominique Sugny, Thomas Halfmann, and Stéphane Guérin

We derive a versatile protocol to implement a fast and robust not quantum gate, driven by single-shot-shaped pulses with appropriate time-dependent phase and intensity profiles. The pulses are derived by combining analytic computations and numerical optimizations. We experimentally demonstrate the a...

[Phys. Rev. A 96, 022309] Published Thu Aug 10, 2017

Qubit entanglement across $ε$-near-zero media


Author(s): S.-A. Biehs and G. S. Agarwal

Currently, epsilon-near-zero (ENZ) materials have become important for controlling the propagation of light and enhancing by several orders of magnitude the Kerr and other nonlinearities. Given this advance it is important to examine the quantum electrodynamic processes and information tasks near EN...

[Phys. Rev. A 96, 022308] Published Wed Aug 09, 2017

Symmetry-protected topological order at nonzero temperature


Author(s): Sam Roberts, Beni Yoshida, Aleksander Kubica, and Stephen D. Bartlett

We address the question of whether symmetry-protected topological (SPT) order can persist at nonzero temperature, with a focus on understanding the thermal stability of several models studied in the theory of quantum computation. We present three results in this direction. First, we prove that nontr...

[Phys. Rev. A 96, 022306] Published Mon Aug 07, 2017

Einstein-Podolsky-Rosen-steering swapping between two Gaussian multipartite entangled states


Author(s): Meihong Wang, Zhongzhong Qin, Yu Wang, and Xiaolong Su

Multipartite Einstein-Podolsky-Rosen (EPR) steering is a useful quantum resource for quantum communication in quantum networks. It has potential applications in secure quantum communication, such as one-sided device-independent quantum key distribution and quantum secret sharing. By distributing opt...

[Phys. Rev. A 96, 022307] Published Mon Aug 07, 2017

Complete Bell-state analysis for superconducting-quantum-interference-device qubits with a transitionless tracking algorithm


Author(s): Yi-Hao Kang, Ye-Hong Chen, Zhi-Cheng Shi, Bi-Hua Huang, Jie Song, and Yan Xia

We propose a protocol for complete Bell-state analysis for two superconducting-quantum-interference-device qubits. The Bell-state analysis could be completed by using a sequence of microwave pulses designed by the transitionless tracking algorithm, which is a useful method in the technique of shortc...

[Phys. Rev. A 96, 022304] Published Fri Aug 04, 2017

Arbitrary multimode Gaussian operations on mechanical cluster states


Author(s): Darren W. Moore, Oussama Houhou, and Alessandro Ferraro

We consider opto- and electromechanical quantum systems composed of a driven cavity mode interacting with a set of mechanical resonators. It has been proposed that the latter can be initialized in arbitrary cluster states, including universal resource states for measurement-based quantum computation...

[Phys. Rev. A 96, 022305] Published Fri Aug 04, 2017

Approximate broadcasting of quantum correlations


Author(s): Wei Xie, Kun Fang, Xin Wang, and Runyao Duan

Broadcasting quantum and classical information is a basic task in quantum information processing, and is also a useful model in the study of quantum correlations including quantum discord. We establish a full operational characterization of two-sided quantum discord in terms of bilocal broadcasting ...

[Phys. Rev. A 96, 022302] Published Thu Aug 03, 2017

Sequential scheme for locally discriminating bipartite unitary operations without inverses


Author(s): Lvzhou Li

Local distinguishability of bipartite unitary operations has recently received much attention. A nontrivial and interesting question concerning this subject is whether there is a sequential scheme for locally discriminating between two bipartite unitary operations, because a sequential scheme usuall...

[Phys. Rev. A 96, 022303] Published Thu Aug 03, 2017

Exact boson sampling using Gaussian continuous-variable measurements


Author(s): A. P. Lund, S. Rahimi-Keshari, and T. C. Ralph

Boson sampling is a quantum mechanical task involving Fock basis state preparation and detection and evolution using only linear interactions. A classical algorithm for producing samples from this quantum task cannot be efficient unless the polynomial hierarchy of complexity classes collapses, a sit...

[Phys. Rev. A 96, 022301] Published Wed Aug 02, 2017

Quantum parameter estimation with the Landau-Zener transition


Author(s): Jing Yang, Shengshi Pang, and Andrew N. Jordan

We investigate the fundamental limits in precision allowed by quantum mechanics from Landau-Zener transitions, concerning Hamiltonian parameters. While the Landau-Zener transition probabilities depend sensitively on the system parameters, much more precision may be obtained using the acquired phase,...

[Phys. Rev. A 96, 020301(R)] Published Tue Aug 01, 2017

Quantum algorithm for linear regression


Author(s): Guoming Wang

We present a quantum algorithm for fitting a linear regression model to a given data set using the least-squares approach. Differently from previous algorithms which yield a quantum state encoding the optimal parameters, our algorithm outputs these numbers in the classical form. So by running it onc...

[Phys. Rev. A 96, 012335] Published Mon Jul 31, 2017

Genuine multipartite nonlocality in the one-dimensional ferromagnetic spin-1/2 chain


Author(s): Yue Dai, Chengjie Zhang, Wenlong You, Yuli Dong, and C. H. Oh

Genuine multipartite entanglement has been found in some spin chain systems. However, genuine multipartite nonlocality is much rarer than genuine multipartite entanglement. Here we present genuine multipartite nonlocality in a spin chain system. After introducing the definition of genuine multiparti...

[Phys. Rev. A 96, 012336] Published Mon Jul 31, 2017

Generation of coherence via Gaussian measurements


Author(s): Francesco Albarelli, Marco G. Genoni, and Matteo G. A. Paris

We address measurement-based generation of quantum coherence in continuous variable systems. We consider Gaussian measurements performed on Gaussian states and focus on two scenarios: In the first one, we assume an initially correlated bipartite state shared by two parties and study how correlations...

[Phys. Rev. A 96, 012337] Published Mon Jul 31, 2017

Theory of noise suppression in $\mathrm{Λ}$-type quantum memories by means of a cavity


Author(s): J. Nunn, J. H. D. Munns, S. Thomas, K. T. Kaczmarek, C. Qiu, A. Feizpour, E. Poem, B. Brecht, D. J. Saunders, P. M. Ledingham, Dileep V. Reddy, M. G. Raymer, and I. A. Walmsley

Quantum memories, capable of storing single photons or other quantum states of light, to be retrieved on demand, offer a route to large-scale quantum information processing with light. A promising class of memories is based on far-off-resonant Raman absorption in ensembles of $\mathrm{Λ}$-type atom...

[Phys. Rev. A 96, 012338] Published Mon Jul 31, 2017

Entanglement dynamics of two two-level atoms in the vicinity of an invisibility cloak


Author(s): Ehsan Amooghorban and Elnaz Aleebrahim

We study the entanglement between two identical two-level atoms located near an ideal model of invisibility cloaks by monitoring the time evolution of the concurrence measure. We obtain the reduced density operator of the atomic subsystem based on a canonical quantization scheme presented for the el...

[Phys. Rev. A 96, 012339] Published Mon Jul 31, 2017

Universal feedback control of two-qubit entanglement


Author(s): Morteza Rafiee, Alireza Nourmandipour, and Stefano Mancini

We consider two qubits undergoing local dissipation and subject to local driving. We then determine the optimal Markovian feedback action to preserve initial entanglement as well as to create stationary entanglement with the help of an $\text{XY}$ interaction Hamiltonian. Such feedback actions are w...

[Phys. Rev. A 96, 012340] Published Mon Jul 31, 2017

Quantum coherence of planar spin models with Dzyaloshinsky-Moriya interaction


Author(s): Chandrashekar Radhakrishnan, Igor Ermakov, and Tim Byrnes

The quantum coherence of one-dimensional planar spin models with Dzyaloshinsky-Moriya interaction is investigated. The anisotropic XY model, the isotropic XX model, and the transverse field model are studied in the large $N$ limit using two qubit reduced density matrices and two point correlation fu...

[Phys. Rev. A 96, 012341] Published Mon Jul 31, 2017

Multiparty quantum mutual information: An alternative definition


Author(s): Asutosh Kumar

Mutual information is the reciprocal information that is common to or shared by two or more parties. Quantum mutual information for bipartite quantum systems is non-negative, and bears the interpretation of total correlation between the two subsystems. This may, however, no longer be true for three ...

[Phys. Rev. A 96, 012332] Published Thu Jul 27, 2017

Degenerate eigensubspace in a triangle-level system and its geometric quantum control


Author(s): Yan-Xiong Du, Bao-Jie Liu, Qing-Xian Lv, Xin-Ding Zhang, Hui Yan, and Shi-Liang Zhu

The non-Abelian geometric phases appear only in a degenerate subspace and the most familiar model with such a subspace is the $N$-pod system. Here we propose an alternative system to realize a non-Abelian gauge structure. We demonstrate that a three-level system with a triangular form can have two d...

[Phys. Rev. A 96, 012333] Published Thu Jul 27, 2017

Fast reconstruction of high-qubit-number quantum states via low-rate measurements


Author(s): K. Li, J. Zhang, and S. Cong

Due to the exponential complexity of the resources required by quantum state tomography (QST), people are interested in approaches towards identifying quantum states which require less effort and time. In this paper, we provide a tailored and efficient method for reconstructing mixed quantum states ...

[Phys. Rev. A 96, 012334] Published Thu Jul 27, 2017

Four-concurrence in the transverse $XY$ spin-1/2 chain


Author(s): Andreas Osterloh and Ralf Schützhold

We analyze the entanglement measure ${C}_{4}$ for specific mixed states in general and for the ground state of the transverse $XY$ spin-1/2 chain. We find that its factorizing property for pure states does not easily extend to mixed states. For cases where the density matrix is a tensor product, ${C...

[Phys. Rev. A 96, 012331] Published Wed Jul 26, 2017

Quasiadiabatic Grover search via the Wentzel-Kramers-Brillouin approximation


Author(s): Siddharth Muthukrishnan and Daniel A. Lidar

In various applications one is interested in quantum dynamics at intermediate evolution times, for which the adiabatic approximation is inadequate. Here we develop a quasiadiabatic approximation based on the WKB method, designed to work for such intermediate evolution times. We apply it to the probl...

[Phys. Rev. A 96, 012329] Published Tue Jul 25, 2017

Strong algorithmic cooling in large star-topology quantum registers


Author(s): Varad R. Pande, Gaurav Bhole, Deepak Khurana, and T. S. Mahesh

Cooling the qubit into a pure initial state is crucial for realizing fault-tolerant quantum information processing. Here we envisage a star-topology arrangement of reset and computation qubits for this purpose. The reset qubits cool or purify the computation qubit by transferring its entropy to a he...

[Phys. Rev. A 96, 012330] Published Tue Jul 25, 2017

Ground-state blockade of Rydberg atoms and application in entanglement generation


Author(s): X. Q. Shao, D. X. Li, Y. Q. Ji, J. H. Wu, and X. X. Yi

We propose a mechanism of ground-state blockade between two $N$-type Rydberg atoms by virtue of the Rydberg-antiblockade effect and the Raman transition. Inspired by the quantum Zeno effect, the strong Rydberg antiblockade interaction plays a role in frequently measuring one ground state of two, lea...

[Phys. Rev. A 96, 012328] Published Mon Jul 24, 2017

One-step generation of continuous-variable quadripartite cluster states in a circuit QED system


Author(s): Zhi-peng Yang, Zhen Li, Sheng-li Ma, and Fu-li Li

We propose a dissipative scheme for one-step generation of continuous-variable quadripartite cluster states in a circuit QED setup consisting of four superconducting coplanar waveguide resonators and a gap-tunable superconducting flux qubit. With external driving fields to adjust the desired qubit-r...

[Phys. Rev. A 96, 012327] Published Fri Jul 21, 2017

Single-laser-pulse implementation of arbitrary $ZYZ$ rotations of an atomic qubit


Author(s): Han-gyeol Lee, Yunheung Song, and Jaewook Ahn

Arbitrary rotation of a qubit can be performed with a three-pulse sequence, for example, $ZYZ$ rotations. However, this requires precise control of the relative phase and timing between the pulses, making it technically challenging in optical implementation in a short time scale. Here we show any $Z...

[Phys. Rev. A 96, 012326] Published Thu Jul 20, 2017

Single-photon-driven high-order sideband transitions in an ultrastrongly coupled circuit-quantum-electrodynamics system


Author(s): Zhen Chen, Yimin Wang, Tiefu Li, Lin Tian, Yueyin Qiu, Kunihiro Inomata, Fumiki Yoshihara, Siyuan Han, Franco Nori, J. S. Tsai, and J. Q. You

We report the experimental observation of high-order sideband transitions at the single-photon level in a quantum circuit system of a flux qubit ultrastrongly coupled to a coplanar waveguide resonator. With the coupling strength reaching 10% of the resonator's fundamental frequency, we obtain clear ...

[Phys. Rev. A 96, 012325] Published Wed Jul 19, 2017

Quantum approach to the unique sink orientation problem


Author(s): Dave Bacon

We consider quantum algorithms for the unique sink orientation problem on cubes. This problem is widely considered to be of intermediate computational complexity. This is because there is no known polynomial algorithm (classical or quantum) for the problem and yet it arises as part of a series of pr...

[Phys. Rev. A 96, 012323] Published Tue Jul 18, 2017

Storage of polarization-entangled THz-bandwidth photons in a diamond quantum memory


Author(s): Kent A. G. Fisher, Duncan G. England, Jean-Philippe W. MacLean, Philip J. Bustard, Khabat Heshami, Kevin J. Resch, and Benjamin J. Sussman

Bulk diamond phonons have been shown to be a versatile platform for the generation, storage, and manipulation of high-bandwidth quantum states of light. Here we demonstrate a diamond quantum memory that stores, and releases on demand, an arbitrarily polarized $∼250$ fs duration photonic qubit. The s...

[Phys. Rev. A 96, 012324] Published Tue Jul 18, 2017

Capacity of optical communications over a lossy bosonic channel with a receiver employing the most general coherent electro-optic feedback control


Author(s): Hye Won Chung, Saikat Guha, and Lizhong Zheng

We study the problem of designing optical receivers to discriminate between multiple coherent states using coherent processing receivers—i.e., one that uses arbitrary coherent feedback control and quantum-noise-limited direct detection—which was shown by Dolinar to achieve the minimum error probabil...

[Phys. Rev. A 96, 012320] Published Mon Jul 17, 2017

Entanglement verification of noisy NOON states


Author(s): M. Bohmann, J. Sperling, and W. Vogel

Entangled quantum states, such as NOON states, are of major importance for quantum technologies due to their quantum-enhanced performance. At the same time, their quantum correlations are relatively vulnerable when they are subjected to imperfections. Therefore, it is crucial to determine under whic...

[Phys. Rev. A 96, 012321] Published Mon Jul 17, 2017

Computational complexity of exterior products and multiparticle amplitudes of noninteracting fermions in entangled states


Author(s): Dmitri A. Ivanov

Noninteracting bosons were proposed to be used for a demonstration of quantum-computing supremacy in a boson-sampling setup. A similar demonstration with fermions would require that the fermions are initially prepared in an entangled state. I suggest that pairwise entanglement of fermions would be s...

[Phys. Rev. A 96, 012322] Published Mon Jul 17, 2017

Suppression of charge noise using barrier control of a singlet-triplet qubit


Author(s): Xu-Chen Yang and Xin Wang

It has been recently demonstrated that a singlet-triplet spin qubit in semiconductor double quantum dots can be controlled by changing the height of the potential barrier between the two dots (“barrier control”), which has led to a considerable reduction of charge noises as compared with the traditi...

[Phys. Rev. A 96, 012318] Published Thu Jul 13, 2017

Characterization of a measurement-based noiseless linear amplifier and its applications


Author(s): Jie Zhao, Jing Yan Haw, Thomas Symul, Ping Koy Lam, and Syed M. Assad

A noiseless linear amplifier (NLA) adds no noise to the signals it processes, which works only in a probabilistic way. It can be realized approximately with either a physical implementation that truncates the working space of the NLA on a photon-number basis or a measurement-based implementation tha...

[Phys. Rev. A 96, 012319] Published Thu Jul 13, 2017

Capacity of coherent-state adaptive decoders with interferometry and single-mode detectors


Author(s): Matteo Rosati, Andrea Mari, and Vittorio Giovannetti

A class of adaptive decoders (ADs) for coherent-state sequences is studied, including in particular the most common technology for optical-signal processing, e.g., interferometers, coherent displacements, and photon-counting detectors. More generally we consider ADs comprising adaptive procedures ba...

[Phys. Rev. A 96, 012317] Published Wed Jul 12, 2017

Cat-state generation and stabilization for a nuclear spin through electric quadrupole interaction


Author(s): Ceyhun Bulutay

Spin cat states are superpositions of two or more coherent spin states (CSSs) that are distinctly separated over the Bloch sphere. Additionally, the nuclei with angular momenta greater than 1/2 possess a quadrupolar charge distribution. At the intersection of these two phenomena, we devise a simple ...

[Phys. Rev. A 96, 012312] Published Tue Jul 11, 2017

Towards a heralded eigenstate-preserving measurement of multi-qubit parity in circuit QED


Author(s): Patrick Huembeli and Simon E. Nigg

Eigenstate-preserving multi-qubit parity measurements lie at the heart of stabilizer quantum error correction, which is a promising approach to mitigate the problem of decoherence in quantum computers. In this work we explore a high-fidelity, eigenstate-preserving parity readout for superconducting ...

[Phys. Rev. A 96, 012313] Published Tue Jul 11, 2017

Cut-and-paste restoration of entanglement transmission


Author(s): Álvaro Cuevas, Andrea Mari, Antonella De Pasquale, Adeline Orieux, Marcello Massaro, Fabio Sciarrino, Paolo Mataloni, and Vittorio Giovannetti

The distribution of entangled quantum systems among two or more nodes of a network is a key task at the basis of quantum communication, quantum computation, and quantum cryptography. Unfortunately, the transmission lines used in this procedure can introduce so many perturbations and so much noise in...

[Phys. Rev. A 96, 012314] Published Tue Jul 11, 2017

Heralded quantum controlled-phase gates with dissipative dynamics in macroscopically distant resonators


Author(s): Wei Qin, Xin Wang, Adam Miranowicz, Zhirong Zhong, and Franco Nori

Heralded near-deterministic multiqubit controlled-phase gates with integrated error detection have recently been proposed by Borregaard et al. [Phys. Rev. Lett. 114, 110502 (2015)]. This protocol is based on a single four-level atom (a heralding quartit) and $N$ three-level atoms (operational qutrit...

[Phys. Rev. A 96, 012315] Published Tue Jul 11, 2017

Estimating temperature via sequential measurements


Author(s): Antonella De Pasquale, Kazuya Yuasa, and Vittorio Giovannetti

We study the efficiency of estimation procedures in which the temperature of an external bath is indirectly recovered by monitoring the transformations induced on a probing system that is put in thermal contact with the bath. In particular we compare the performances of sequential measurement scheme...

[Phys. Rev. A 96, 012316] Published Tue Jul 11, 2017

Engineering autonomous error correction in stabilizer codes at finite temperature


Author(s): C. Daniel Freeman, C. M. Herdman, and K. B. Whaley

We present an error-correcting protocol that enhances the lifetime of stabilizer code–based qubits which are susceptible to the creation of pairs of localized defects (due to stringlike error operators) at finite temperature, such as the toric code. The primary tool employed is periodic application ...

[Phys. Rev. A 96, 012311] Published Mon Jul 10, 2017

Quantum metrology matrix


Author(s): Haidong Yuan and Chi-Hang Fred Fung

Various strategies exist in quantum metrology, such as with or without ancillary system, with a fixed or optimized measurement, with or without monitoring the environment, etc. Different set of tools are usually needed for different strategies. In this article, we provide a unified framework for the...

[Phys. Rev. A 96, 012310] Published Fri Jul 07, 2017

Exact stabilization of entangled states in finite time by dissipative quantum circuits


Author(s): Peter D. Johnson, Francesco Ticozzi, and Lorenza Viola

Open quantum systems evolving according to discrete-time dynamics are capable, unlike continuous-time counterparts, to converge to a stable equilibrium in finite time with zero error. We consider dissipative quantum circuits consisting of sequences of quantum channels subject to specified quasi-loca...

[Phys. Rev. A 96, 012308] Published Thu Jul 06, 2017

Intrinsic errors in transporting a single-spin qubit through a double quantum dot


Author(s): Xiao Li, Edwin Barnes, J. P. Kestner, and S. Das Sarma

Coherent spatial transport or shuttling of a single electron spin through semiconductor nanostructures is an important ingredient in many spintronic and quantum computing applications. In this work we analyze the possible errors in solid-state quantum computation due to leakage in transporting a sin...

[Phys. Rev. A 96, 012309] Published Thu Jul 06, 2017

Sufficiency of quantum non-Gaussianity for discrete-variable quantum key distribution over noisy channels


Author(s): Mikołaj Lasota, Radim Filip, and Vladyslav C. Usenko

Quantum key distribution can be enhanced and extended if nonclassical single-photon states of light are used. We study a connection between the security of quantum key distribution and quantum non-Gaussianity of light arriving at the receiver's detection system after the propagation through a noisy ...

[Phys. Rev. A 96, 012301] Published Wed Jul 05, 2017

Symmetry-protected topological phases with uniform computational power in one dimension


Author(s): Robert Raussendorf, Dong-Sheng Wang, Abhishodh Prakash, Tzu-Chieh Wei, and David T. Stephen

We investigate the usefulness of ground states of quantum spin chains with symmetry-protected topological order (SPTO) for measurement-based quantum computation. We show that, in spatial dimension 1, if an SPTO phase protects the identity gate, then, subject to an additional symmetry condition that ...

[Phys. Rev. A 96, 012302] Published Wed Jul 05, 2017

Unconditionally verifiable blind quantum computation


Author(s): Joseph F. Fitzsimons and Elham Kashefi

Blind quantum computing (BQC) allows a client to have a server carry out a quantum computation for them such that the client's input, output, and computation remain private. A desirable property for any BQC protocol is verification, whereby the client can verify with high probability whether the ser...

[Phys. Rev. A 96, 012303] Published Wed Jul 05, 2017

Information-theoretic limitations on approximate quantum cloning and broadcasting


Author(s): Marius Lemm and Mark M. Wilde

We prove quantitative limitations on any approximate simultaneous cloning or broadcasting of mixed states. The results are based on information-theoretic (entropic) considerations and generalize the well-known no-cloning and no-broadcasting theorems. We also observe and exploit the fact that the uni...

[Phys. Rev. A 96, 012304] Published Wed Jul 05, 2017

Finite-key analysis for quantum key distribution with weak coherent pulses based on Bernoulli sampling


Author(s): Shun Kawakami, Toshihiko Sasaki, and Masato Koashi

An essential step in quantum key distribution is the estimation of parameters related to the leaked amount of information, which is usually done by sampling of the communication data. When the data size is finite, the final key rate depends on how the estimation process handles statistical fluctuati...

[Phys. Rev. A 96, 012305] Published Wed Jul 05, 2017

Factoring with qutrits: Shor's algorithm on ternary and metaplectic quantum architectures


Author(s): Alex Bocharov, Martin Roetteler, and Krysta M. Svore

We determine the cost of performing Shor's algorithm for integer factorization on a ternary quantum computer, using two natural models of universal fault-tolerant computing: (i) a model based on magic state distillation that assumes the availability of the ternary Clifford gates, projective measurem...

[Phys. Rev. A 96, 012306] Published Wed Jul 05, 2017

Electric nonadiabatic geometric entangling gates on spin qubits


Author(s): Vahid Azimi Mousolou

Producing and maintaining entanglement reside at the heart of the optimal construction of quantum operations and are fundamental issues in the realization of universal quantum computation. We here introduce a setup of spin qubits that allows the geometric implementation of entangling gates between t...

[Phys. Rev. A 96, 012307] Published Wed Jul 05, 2017

Coherent-state constellations and polar codes for thermal Gaussian channels


Author(s): Felipe Lacerda, Joseph M. Renes, and Volkher B. Scholz

Optical communication channels are ultimately quantum mechanical in nature, and we must therefore look beyond classical information theory to determine their communication capacity as well as to find efficient encoding and decoding schemes of the highest rates. Thermal channels, which arise from lin...

[Phys. Rev. A 95, 062343] Published Fri Jun 30, 2017

Simple derivation of the Weyl and Dirac quantum cellular automata


Author(s): Philippe Raynal

We consider quantum cellular automata on a body-centered cubic lattice and provide a simple derivation of the only two homogenous, local, isotropic, and unitary two-dimensional automata [G. M. D'Ariano and P. Perinotti, Phys. Rev. A 90, 062106 (2014)]. Our derivation relies on the notion of Gram mat...

[Phys. Rev. A 95, 062344] Published Fri Jun 30, 2017

Quantum error-correction failure distributions: Comparison of coherent and stochastic error models


Author(s): Jeff P. Barnes, Colin J. Trout, Dennis Lucarelli, and B. D. Clader

A comparison between different types of error models is performed. The investigation highlights the need for extra caution when choosing an adequate quantum error-correction routine, which is an essential step for fault-tolerant quantum computation.

[Phys. Rev. A 95, 062338] Published Thu Jun 29, 2017

Dissipation-based entanglement via quantum Zeno dynamics and Rydberg antiblockade


Author(s): X. Q. Shao, J. H. Wu, and X. X. Yi

A scheme is proposed for dissipative generation of maximally entanglement between two Rydberg atoms in the context of cavity QED. The spontaneous emission of atoms combined with quantum Zeno dynamics and the Rydberg antiblockade guarantees a unique steady solution of the master equation of the syste...

[Phys. Rev. A 95, 062339] Published Thu Jun 29, 2017

Discordlike correlation of bipartite coherence


Author(s): Yu Guo and Sumit Goswami

Quantum discord has been studied extensively as a measure of nonclassical correlations which includes entanglement as a subset. Although it is well known that nonzero discord can exist without entanglement, the origin of quantum discord is not well understood as compared to entanglement, which manif...

[Phys. Rev. A 95, 062340] Published Thu Jun 29, 2017

Monotonic quantum-to-classical transition enabled by positively correlated biphotons


Author(s): Rui-Bo Jin, Guo-Qun Chen, Hui Jing, Changliang Ren, Pei Zhao, Ryosuke Shimizu, and Pei-Xiang Lu

Multiparticle interference is a fundamental phenomenon in the study of quantum mechanics. It was discovered in a recent experiment [Y.-S. Ra et al., Proc. Natl. Acad. Sci. USA 110, 1227 (2013)] that spectrally uncorrelated biphotons exhibited a nonmonotonic quantum-to-classical transition in a four...

[Phys. Rev. A 95, 062341] Published Thu Jun 29, 2017

Enhancing sensitivity in quantum metrology by Hamiltonian extensions


Author(s): Julien Mathieu Elias Fraïsse and Daniel Braun

A well-studied scenario in quantum parameter estimation theory arises when the parameter to be estimated is imprinted on the initial state by a Hamiltonian of the form $θG$. For such “phase-shift Hamiltonians” it has been shown that one cannot improve the channel quantum Fisher information by adding...

[Phys. Rev. A 95, 062342] Published Thu Jun 29, 2017

Unbiased simulation of near-Clifford quantum circuits


Author(s): Ryan S. Bennink, Erik M. Ferragut, Travis S. Humble, Jason A. Laska, James J. Nutaro, Mark G. Pleszkoch, and Raphael C. Pooser

Modeling and simulation are essential for predicting and verifying the behavior of fabricated quantum circuits, but existing simulation methods are either impractically costly or require an unrealistic simplification of error processes. We present a method of simulating noisy Clifford circuits that ...

[Phys. Rev. A 95, 062337] Published Wed Jun 28, 2017

Hybrid benchmarking of arbitrary quantum gates


Author(s): Tobias Chasseur, Daniel M. Reich, Christiane P. Koch, and Frank K. Wilhelm

We present a protocol for interleaved randomized benchmarking of arbitrary quantum gates using Monte Carlo sampling of quantum states. It is generally applicable, including non-Clifford gates while preserving key advantages of randomized benchmarking such as error amplification as well as independen...

[Phys. Rev. A 95, 062335] Published Tue Jun 27, 2017

Superfast maximum-likelihood reconstruction for quantum tomography


Author(s): Jiangwei Shang, Zhengyun Zhang, and Hui Khoon Ng

Conventional methods for computing maximum-likelihood estimators (MLE) often converge slowly in practical situations, leading to a search for simplifying methods that rely on additional assumptions for their validity. In this work, we provide a fast and reliable algorithm for maximum-likelihood reco...

[Phys. Rev. A 95, 062336] Published Tue Jun 27, 2017

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


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

Genuine $N$-partite entanglement without $N$-partite correlation functions


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

Construction of optimal resources for concatenated quantum protocols


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

Quantum key distribution protocol based on contextuality monogamy


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

Quantum money with nearly optimal error tolerance


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...

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

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


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 independ...

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

Monogamy inequality for entanglement and local contextuality


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

Resource theory of coherence: Beyond states


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

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


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

Robust quantum gates for stochastic time-varying noise


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

Quantum and random walks as universal generators of probability distributions


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

Self-testing of binary observables based on commutation


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

Nonadditivity of Rains' bound for distillable entanglement


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

Bipartite entanglement in fermion systems


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

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


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

General scheme for preparation of different topological states on cluster states


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

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


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

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


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

Optimal shortcut approach based on an easily obtained intermediate Hamiltonian


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

Experimental bilocality violation without shared reference frames


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

Quantum resource theories in the single-shot regime


Author(s): Gilad Gour

One of the main goals of any resource theory such as entanglement, quantum thermodynamics, quantum coherence, and asymmetry, is to find necessary and sufficient conditions that determine whether one resource can be converted to another by the set of free operations. Here we find such conditions for ...

[Phys. Rev. A 95, 062314] Published Thu Jun 08, 2017

Robustness of quantum key distribution with discrete and continuous variables to channel noise


Author(s): Mikołaj Lasota, Radim Filip, and Vladyslav C. Usenko

We study the robustness of quantum key distribution protocols using discrete or continuous variables to the channel noise. We introduce the model of such noise based on coupling of the signal to a thermal reservoir, typical for continuous-variable quantum key distribution, to the discrete-variable c...

[Phys. Rev. A 95, 062312] Published Wed Jun 07, 2017

Improved measurement-device-independent quantum key distribution with uncharacterized qubits


Author(s): Won-Young Hwang, Hong-Yi Su, and Joonwoo Bae

We propose an improved bound for the difference between phase and bit error rate in measurement-device-independent quantum key distribution with uncharacterized qubits. We show by simulations that the bound considerably increases the final key rates.

[Phys. Rev. A 95, 062313] Published Wed Jun 07, 2017

Single-shot realization of nonadiabatic holonomic quantum gates in decoherence-free subspaces


Author(s): P. Z. Zhao, G. F. Xu, Q. M. Ding, Erik Sjöqvist, and D. M. Tong

Nonadiabatic holonomic quantum computation in decoherence-free subspaces has attracted increasing attention recently, as it allows for high-speed implementation and combines both the robustness of holonomic gates and the coherence stabilization of decoherence-free subspaces. Since the first protocol...

[Phys. Rev. A 95, 062310] Published Tue Jun 06, 2017

Upper bound on three-tangles of reduced states of four-qubit pure states


Author(s): S. Shelly Sharma and N. K. Sharma

Closed formulas for upper bounds on three-tangles of three-qubit reduced states in terms of three-qubit–invariant polynomials of pure four-qubit states are obtained. Our results offer tighter constraints on total three-way entanglement of a given qubit with the rest of the system than those used by ...

[Phys. Rev. A 95, 062311] Published Tue Jun 06, 2017

Criteria for universality of quantum gates


Author(s): Adam Sawicki and Katarzyna Karnas

Compact-form criteria are provided for deciding universality of a given set of gates in a finite number of steps. The criteria may also indicate what types of gates can be added to a set of nonuniversal gates to turn it into a universal set.

[Phys. Rev. A 95, 062303] Published Mon Jun 05, 2017

Limitations of two-level emitters as nonlinearities in two-photon controlled-phase gates


Author(s): Anders Nysteen, Dara P. S. McCutcheon, Mikkel Heuck, Jesper Mørk, and Dirk R. Englund

We investigate the origin of imperfections in the fidelity of a two-photon controlled-phase gate based on two-level-emitter nonlinearities. We focus on a passive system that operates without external modulations to enhance its performance. We demonstrate that the fidelity of the gate is limited by o...

[Phys. Rev. A 95, 062304] Published Mon Jun 05, 2017

Measurement-device-independent randomness generation with arbitrary quantum states


Author(s): Felix Bischof, Hermann Kampermann, and Dagmar Bruß

Measurements of quantum systems can be used to generate classical data that are truly unpredictable for every observer. However, this true randomness needs to be discriminated from randomness due to ignorance or lack of control of the devices. We analyze the randomness gain of a measurement-device-i...

[Phys. Rev. A 95, 062305] Published Mon Jun 05, 2017

Quantum voting and violation of Arrow's impossibility theorem


Author(s): Ning Bao and Nicole Yunger Halpern

A quantum voting system is proposed in the tradition of quantum game theory. It is shown that this system violates the quantum analogy of Arrow’s impossibility theorem, which makes claims about dictatorship in a classical electoral system.

[Phys. Rev. A 95, 062306] Published Mon Jun 05, 2017

Estimating phase with a random generator: Strategies and resources in multiparameter quantum metrology


Author(s): Rozhin Yousefjani, Rosanna Nichols, Shahriar Salimi, and Gerardo Adesso

Quantum metrology aims to exploit quantum phenomena to overcome classical limitations in the estimation of relevant parameters. We consider a probe undergoing a phase shift $φ$ whose generator is randomly sampled according to a distribution with unknown concentration $κ$, which introduces a physical...

[Phys. Rev. A 95, 062307] Published Mon Jun 05, 2017

Superadiabatic holonomic quantum computation in cavity QED


Author(s): Bao-Jie Liu, Zhen-Hua Huang, Zheng-Yuan Xue, and Xin-Ding Zhang

Adiabatic quantum control is a powerful tool for quantum engineering and a key component in some quantum computation models, where accurate control over the timing of the involved pulses is not needed. However, the adiabatic condition requires that the process be very slow and thus limits its applic...

[Phys. Rev. A 95, 062308] Published Mon Jun 05, 2017

Non-Gaussian operations on bosonic modes of light: Photon-added Gaussian channels


Author(s): Krishna Kumar Sabapathy and Andreas Winter

A systematic framework to study linear bosonic non-Gaussian channels of continuous-variable systems is presented. The non-Gaussian channels investigated are realized by extending quantum-limited Gaussian channels with photon addition applied to the environment state in the Stinespring dilation of these channels.

[Phys. Rev. A 95, 062309] Published Mon Jun 05, 2017