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To improve the performance of a quantum key distribution (QKD) system, high speed, low dark count single photon detectors (or low noise homodyne detectors) are required. However, in practice, a fast detector is usually noisy. Here, we…

Quantum Physics · Physics 2009-11-13 Bing Qi , Yi Zhao , Xiongfeng Ma , Hoi-Kwong Lo , Li Qian

In recent years, there has been a great effort to prove the security of quantum key distribution (QKD) with a minimum number of assumptions. Besides its intrinsic theoretical interest, this would allow for larger tolerance against device…

Quantum Physics · Physics 2018-03-28 Kiyoshi Tamaki , Marcos Curty , Marco Lucamarini

The security of quantum key distribution (QKD) relies on the Heisenberg uncertainty principle, with which legitimate users are able to estimate information leakage by monitoring the disturbance of the transmitted quantum signals. Normally,…

Quantum Physics · Physics 2017-04-03 Zhen Zhang , Xiao Yuan , Zhu Cao , Xiongfeng Ma

Variations of phase-matching measurement-device-independent quantum key distribution (PM-MDI QKD) protocols have been investigated before, but it was recently discovered that this type of protocol (under the name of twin-field QKD) can beat…

Quantum Physics · Physics 2018-10-30 Jie Lin , Norbert Lütkenhaus

In this paper, we study the unconditional security of the so-called measurement device independent quantum key distribution (MDIQKD) with the basis-dependent flaw in the context of phase encoding schemes. We propose two schemes for the…

Quantum Physics · Physics 2015-06-03 Kiyoshi Tamaki , Hoi-Kwong Lo , Chi-Hang Fred Fung , Bing Qi

Future global quantum communication networks, or quantum Internet, will realize high-rate secure communication and entanglement distribution for large-scale users over long distances. Continuous variable (CV) quantum key distribution (QKD)…

Quantum Physics · Physics 2026-02-26 Zhiyue Zuo , Masoud Ghalaii , Stefano Pirandola

We analyze the dynamics of entanglement entropy in a generic quantum many-body open system from the perspective of quantum information and error corrections. We introduce a random unitary circuit model with intermittent projective…

Quantum Physics · Physics 2020-07-17 Soonwon Choi , Yimu Bao , Xiao-Liang Qi , Ehud Altman

Optical homodyne detection has been widely used in continuous-variable (CV) quantum information processing for measuring field quadrature values. In this paper we explore the possibility of operating a conjugate homodyne detection system in…

Quantum Physics · Physics 2021-01-22 Bing Qi

Optical key distribution (OKD) protects the physical layer of communication links by taking advantage of the inherent noise present in the photodetection process. It allows for efficient generation of a shared random key between two distant…

Quantum Physics · Physics 2026-03-24 Karol Łukanowski , Michał Wójcik , Stefano Olivares , Konrad Banaszek , Marcin Jarzyna

Quantum key distribution (QKD) allows two distant parties to share secret keys with the proven security even in the presence of an eavesdropper with unbounded computational power. Recently, GHz-clock decoy QKD systems have been realized by…

It is known that placing a mechanical oscillator in a superposition of coherent states allows, in theory, a measurement of a linear force whose sensitivity increases with the amplitude of the mechanical oscillations, a uniquely quantum…

Quantum Physics · Physics 2017-09-13 Kurt Jacobs , Radhakrishnan Balu , John D. Teufel

Quantum key distribution (QKD) allows two users to exchange a provably secure key for cryptographic applications. In prepare-and-measure QKD protocols, the states must be indistinguishable to prevent information leakage to an eavesdropper…

The sensitivity in optical interferometry is strongly affected by losses during the signal propagation or at the detection stage. The optimal quantum states of the probing signals in the presence of loss were recently found. However, in…

In this paper, we use the non-linear dynamics of the individual quantum trajectories of an optical cavity inside an instantaneous quantum feedback loop to measure the phase shift between two pathways of light with an accuracy above the…

Quantum Physics · Physics 2016-08-31 Lewis A. Clark , Adam Stokes , Almut Beige

Throughout history, every advance in encryption has been defeated by advances in hacking with severe consequences. Quantum cryptography holds the promise to end this battle by offering unconditional security when ideal single-photon sources…

Digital signatures ensure the integrity of a classical message and the authenticity of its sender. Despite their far-reaching use in modern communication, currently used signature schemes rely on computational assumptions and will be…

Quantum Physics · Physics 2022-12-26 Matthew Thornton , Hannah Scott , Callum Croal , Natalia Korolkova

We describe a scheme for quantum error correction that employs feedback and weak measurement rather than the standard tools of projective measurement and fast controlled unitary gates. The advantage of this scheme over previous protocols…

Quantum Physics · Physics 2009-11-10 Mohan Sarovar , Charlene Ahn , Kurt Jacobs , Gerard J. Milburn

Quantum key distribution (QKD) enables two remote parties to share encryption keys with security based on the laws of physics. Continuous variable (CV) QKD with coherent states and coherent detection integrates well with existing…

The performance of quantum key distribution (QKD) is severely limited by multiphoton emissions, due to the photon-number-splitting attack. The most efficient solution, the decoy-state method, requires that the phases of all transmitted…

A novel protocol - measurement-device-independent quantum key distribution (MDI-QKD) - removes all attacks from the detection system, the most vulnerable part in QKD implementations. In this paper, we present an analysis for practical…

Quantum Physics · Physics 2013-11-14 Feihu Xu , Marcos Curty , Bing Qi , Hoi-Kwong Lo