PRA: Quantum information

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Recently published articles in Phys. Rev. A in the Table of Content section "Quantum information"
Updated: 30 min 57 sec ago

Adaptive estimation of a time-varying phase with coherent states: Smoothing can give an unbounded improvement over filtering

5 hours 4 min ago

Author(s): Kiarn T. Laverick, Howard M. Wiseman, Hossein T. Dinani, and Dominic W. Berry

The problem of measuring a time-varying phase, even when the statistics of the variation is known, is considerably harder than that of measuring a constant phase. In particular, the usual bounds on accuracy, such as the 1/(4n¯) standard quantum limit with coherent states, do not apply. Here, by rest...


[Phys. Rev. A 97, 042334] Published Mon Apr 23, 2018

Categories: Journals, Physics

Extended analysis of the Trojan-horse attack in quantum key distribution

5 hours 4 min ago

Author(s): Scott E. Vinay and Pieter Kok

The discrete-variable quantum key distribution protocols based on the 1984 protocol of Bennett and Brassard (BB84) are known to be secure against an eavesdropper, Eve, intercepting the flying qubits and performing any quantum operation on them. However, these protocols may still be vulnerable to sid...


[Phys. Rev. A 97, 042335] Published Mon Apr 23, 2018

Categories: Journals, Physics

Entanglement criterion for tripartite systems based on local sum uncertainty relations

Thu, 2018-04-19 12:00

Author(s): Y. Akbari-Kourbolagh and M. Azhdargalam

We propose a sufficient criterion for the entanglement of tripartite systems based on local sum uncertainty relations for arbitrarily chosen observables of subsystems. This criterion generalizes the tighter criterion for bipartite systems introduced by Zhang et al. [C.-J. Zhang, H. Nha, Y.-S. Zhang,...


[Phys. Rev. A 97, 042333] Published Thu Apr 19, 2018

Categories: Journals, Physics

Scrambling of quantum information in quantum many-body systems

Wed, 2018-04-18 12:00

Author(s): Eiki Iyoda and Takahiro Sagawa

We systematically investigate scrambling (or delocalizing) processes of quantum information encoded in quantum many-body systems by using numerical exact diagonalization. As a measure of scrambling, we adopt the tripartite mutual information (TMI) that becomes negative when quantum information is de...


[Phys. Rev. A 97, 042330] Published Wed Apr 18, 2018

Categories: Journals, Physics

Measurement-device-independent quantum key distribution with correlated source-light-intensity errors

Wed, 2018-04-18 12:00

Author(s): Cong Jiang, Zong-Wen Yu, and Xiang-Bin Wang

We present an analysis for measurement-device-independent quantum key distribution with correlated source-light-intensity errors. Numerical results show that the results here can greatly improve the key rate especially with large intensity fluctuations and channel attenuation compared with prior res...


[Phys. Rev. A 97, 042331] Published Wed Apr 18, 2018

Categories: Journals, Physics

Weighted polygamy inequalities of multiparty entanglement in arbitrary-dimensional quantum systems

Wed, 2018-04-18 12:00

Author(s): Jeong San Kim

We provide a generalization for the polygamy constraint of multiparty entanglement in arbitrary-dimensional quantum systems. By using the βth power of entanglement of assistance for 0≤β≤1 and the Hamming weight of the binary vector related with the distribution of subsystems, we establish a class of...


[Phys. Rev. A 97, 042332] Published Wed Apr 18, 2018

Categories: Journals, Physics

Continuous-variable measurement-device-independent quantum key distribution with virtual photon subtraction

Tue, 2018-04-17 12:00

Author(s): Yijia Zhao, Yichen Zhang, Bingjie Xu, Song Yu, and Hong Guo

The method of improving the performance of continuous-variable quantum key distribution protocols by postselection has been recently proposed and verified. In continuous-variable measurement-device-independent quantum key distribution (CV-MDI QKD) protocols, the measurement results are obtained from...


[Phys. Rev. A 97, 042328] Published Tue Apr 17, 2018

Categories: Journals, Physics

Continuous-variable measurement-device-independent quantum key distribution with photon subtraction

Tue, 2018-04-17 12:00

Author(s): Hong-Xin Ma, Peng Huang, Dong-Yun Bai, Shi-Yu Wang, Wan-Su Bao, and Gui-Hua Zeng

It has been found that non-Gaussian operations can be applied to increase and distill entanglement between Gaussian entangled states. We show the successful use of the non-Gaussian operation, in particular, photon subtraction operation, on the continuous-variable measurement-device-independent quant...


[Phys. Rev. A 97, 042329] Published Tue Apr 17, 2018

Categories: Journals, Physics

Neural-network-designed pulse sequences for robust control of singlet-triplet qubits

Mon, 2018-04-16 12:00

Author(s): Xu-Chen Yang, Man-Hong Yung, and Xin Wang

Composite pulses are essential for universal manipulation of singlet-triplet spin qubits. In the absence of noise, they are required to perform arbitrary single-qubit operations due to the special control constraint of a singlet-triplet qubit, while in a noisy environment, more complicated sequences...


[Phys. Rev. A 97, 042324] Published Mon Apr 16, 2018

Categories: Journals, Physics

Mode entanglement of Gaussian fermionic states

Mon, 2018-04-16 12:00

Author(s): C. Spee, K. Schwaiger, G. Giedke, and B. Kraus

The entanglement properties of multipartite Gaussian fermionic states are investigated. It is shown that there exist no nontrivial Gaussian local operations assisted by classical communication among pure fully entangled Gaussian fermionic states.


[Phys. Rev. A 97, 042325] Published Mon Apr 16, 2018

Categories: Journals, Physics

Leakage and sweet spots in triple-quantum-dot spin qubits: A molecular-orbital study

Mon, 2018-04-16 12:00

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

A triple-quantum-dot system can be operated as either an exchange-only qubit or a resonant-exchange qubit. While it is generally believed that the decisive advantage of the resonant-exchange qubit is the suppression of charge noise because it is operated at a sweet spot, we show that the leakage is ...


[Phys. Rev. A 97, 042326] Published Mon Apr 16, 2018

Categories: Journals, Physics

Towers of generalized divisible quantum codes

Mon, 2018-04-16 12:00

Author(s): Jeongwan Haah

A divisible binary classical code is one in which every code word has weight divisible by a fixed integer. If the divisor is for a positive integer ν, then one can construct a Calderbank-Shor-Steane (CSS) code, where X-stabilizer space is the divisible classical code, that admits a transversal ga...


[Phys. Rev. A 97, 042327] Published Mon Apr 16, 2018

Categories: Journals, Physics

Practical quantum appointment scheduling

Thu, 2018-04-12 12:00

Author(s): Dave Touchette, Benjamin Lovitz, and Norbert Lütkenhaus

A quantum appointment-scheduling protocol based on coherent states and basic linear optics operations is proposed. The protocol is shown to perform better than a classical one in terms of information leakage.


[Phys. Rev. A 97, 042320] Published Thu Apr 12, 2018

Categories: Journals, Physics

Stochastic gradient ascent outperforms gamers in the Quantum Moves game

Thu, 2018-04-12 12:00

Author(s): Dries Sels

Are human players suitable to deliver good strategies for developing quantum protocols? While recent results suggest a positive answer to this question, here a simple stochastic local optimization method is shown to outperform all players.


[Phys. Rev. A 97, 040302(R)] Published Thu Apr 12, 2018

Categories: Journals, Physics

Many-body strategies for multiqubit gates: Quantum control through Krawtchouk-chain dynamics

Thu, 2018-04-12 12:00

Author(s): Koen Groenland and Kareljan Schoutens

We propose a strategy for engineering multiqubit quantum gates. As a first step, it employs an eigengate to map states in the computational basis to eigenstates of a suitable many-body Hamiltonian. The second step employs resonant driving to enforce a transition between a single pair of eigenstates,...


[Phys. Rev. A 97, 042321] Published Thu Apr 12, 2018

Categories: Journals, Physics

Simple expression for the quantum Fisher information matrix

Thu, 2018-04-12 12:00

Author(s): Dominik Šafránek

Quantum Fisher information matrix (QFIM) is a cornerstone of modern quantum metrology and quantum information geometry. Apart from optimal estimation, it finds applications in description of quantum speed limits, quantum criticality, quantum phase transitions, coherence, entanglement, and irreversib...


[Phys. Rev. A 97, 042322] Published Thu Apr 12, 2018

Categories: Journals, Physics

Classical verification of quantum circuits containing few basis changes

Wed, 2018-04-11 12:00

Author(s): Tommaso F. Demarie, Yingkai Ouyang, and Joseph F. Fitzsimons

We consider the task of verifying the correctness of quantum computation for a restricted class of circuits which contain at most two basis changes. This contains circuits giving rise to the second level of the Fourier hierarchy, the lowest level for which there is an established quantum advantage. ...


[Phys. Rev. A 97, 042319] Published Wed Apr 11, 2018

Categories: Journals, Physics

Dark state polarizing a nuclear spin in the vicinity of a nitrogen-vacancy center

Tue, 2018-04-10 12:00

Author(s): Yang-Yang Wang (王洋洋), Jing Qiu (邱静), Ying-Qi Chu (褚莹琦), Mei Zhang (章梅), Jianming Cai (蔡建明), Qing Ai (艾清), and Fu-Guo Deng (邓富国)

The nuclear spin in the vicinity of a nitrogen-vacancy (NV) center possesses long coherence time and convenient manipulation assisted by the strong hyperfine interaction with the NV center. It is suggested for the subsequent quantum information storage and processing after appropriate initialization...


[Phys. Rev. A 97, 042313] Published Tue Apr 10, 2018

Categories: Journals, Physics

Reservoir-engineered entanglement in a hybrid modulated three-mode optomechanical system

Tue, 2018-04-10 12:00

Author(s): Chang-Geng Liao, Rong-Xin Chen, Hong Xie, and Xiu-Min Lin

We propose an effective approach for generating highly pure and strong cavity-mechanical entanglement (or optical-microwave entanglement) in a hybrid modulated three-mode optomechanical system. By applying two-tone driving to the cavity and modulating the coupling strength between two mechanical osc...


[Phys. Rev. A 97, 042314] Published Tue Apr 10, 2018

Categories: Journals, Physics

Quantum machine learning for quantum anomaly detection

Tue, 2018-04-10 12:00

Author(s): Nana Liu and Patrick Rebentrost

Anomaly detection is used for identifying data that deviate from “normal” data patterns. Its usage on classical data finds diverse applications in many important areas such as finance, fraud detection, medical diagnoses, data cleaning, and surveillance. With the advent of quantum technologies, anoma...


[Phys. Rev. A 97, 042315] Published Tue Apr 10, 2018

Categories: Journals, Physics