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We give an achievable secret key rate of a binary modulated continuous variable quantum key distribution schemes in the collective attack scenario considering quantum channels that impose arbitrary noise on the exchanged signals. Bob…

Quantum Physics · Physics 2009-11-13 Yi-Bo Zhao , Matthias Heid , Johannes Rigas , Norbert Lütkenhaus

We analyse the distribution of secure keys using quantum cryptography based on the continuous variable degree of freedom of entangled photon pairs. We derive the information capacity of a scheme based on the spatial entanglement of photons…

Quantum Physics · Physics 2009-11-13 Lijian Zhang , Christine Silberhorn , Ian A. Walmsley

We establish a lower bound on the asymptotic secret key rate of continuous-variable quantum key distribution with a discrete modulation of coherent states. The bound is valid against collective attacks and is obtained by formulating the…

Quantum Physics · Physics 2019-06-27 Shouvik Ghorai , Philippe Grangier , Eleni Diamanti , Anthony Leverrier

We present and demonstrate a new protocol for practical quantum cryptography, tailored for an implementation with weak coherent pulses to obtain a high key generation rate. The key is obtained by a simple time-of-arrival measurement on the…

Quantum Physics · Physics 2009-11-11 Damien Stucki , Nicolas Brunner , Nicolas Gisin , Valerio Scarani , Hugo Zbinden

A key requirement for scalable quantum computing is that elementary quantum gates can be implemented with sufficiently low error. One method for determining the error behavior of a gate implementation is to perform process tomography.…

As quantum computing advances toward early fault-tolerant machines, testing and verification of quantum programs become urgent but costly, since each execution consumes scarce hardware resources. Unlike in classical software testing, every…

Quantum Physics · Physics 2025-10-28 Andriy Miranskyy

Current techniques in quantum process tomography typically return a single point estimate of an unknown process based on a finite albeit large amount of measurement data. Due to statistical fluctuations, however, other processes close to…

Quantum Physics · Physics 2019-05-15 Le Phuc Thinh , Philippe Faist , Jonas Helsen , David Elkouss , Stephanie Wehner

Noise mechanisms in quantum systems can be broadly characterized as either coherent (i.e., unitary) or incoherent. For a given fixed average error rate, coherent noise mechanisms will generally lead to a larger worst-case error than…

Quantum Physics · Physics 2019-01-29 Joel J. Wallman , Christopher Granade , Robin Harper , Steven T. Flammia

Quantum key distribution is an effective encryption technique which can be used to perform secure quantum communication between satellite and ground stations. Quantum cryptography enhances security in various networks such as optical fibers…

Quantum Physics · Physics 2018-07-20 Vishal Sharma , Subhashish Banerjee

Quantum continuous variables are being explored as an alternative means to implement quantum key distribution, which is usually based on single photon counting. The former approach is potentially advantageous because it should enable higher…

Quantum Physics · Physics 2009-11-10 F. Grosshans , G. Van Assche , J. Wenger , R. Brouri , N. J. Cerf , Ph. Grangier

This paper discusses the use of computer-aided verification as a practical means for analysing quantum information systems; specifically, the BB84 protocol for quantum key distribution is examined using this method. This protocol has been…

Cryptography and Security · Computer Science 2007-05-23 Rajagopal Nagarajan , Nikolaos Papanikolaou , Garry Bowen , Simon Gay

Recently, we proposed a simultaneous quantum and classical communication (SQCC) protocol, where random numbers for quantum key distribution (QKD) and bits for classical communication are encoded on the \emph{same} weak coherent pulse, and…

Quantum Physics · Physics 2018-05-16 Bing Qi , Charles Ci Wen Lim

In this thesis we study the finite-size analysis of two continuous-variables quantum key distribution schemes. The first one is the one-way protocol using Gaussian modulation of thermal states and the other is the…

Quantum Physics · Physics 2019-06-13 Panagiotis Papanastasiou

Quantum key distribution (QKD) gradually has become a crucial element of practical secure communication. In different scenarios, the security analysis of genuine QKD systems is complicated. A universal secret key rate calculation method,…

Quantum Physics · Physics 2021-09-13 Zehong Chang , Fumin Wang , Xiaoli Wang , Xiaofei Liu , Rongqian Wu , Yi lv , Pei Zhang

Semi-quantum key distribution (SQKD) allows sharing random keys between a quantum user and a classical user, which significantly saves user resources, especially when using the Single-state protocol. However, the operation of the classical…

Efforts to scale-up quantum computation have reached a point where the principal limiting factor is not the number of qubits, but the entangling gate infidelity. However, the highly detailed system characterization required to understand…

In the near-term noisy intermediate-scale quantum (NISQ) era, high noise will significantly reduce the fidelity of quantum computing. Besides, the noise on quantum devices is not stable. This leads to a challenging problem: At run-time, is…

Quantum Physics · Physics 2023-09-13 Zhirui Hu , Robert Wolle , Mingzhen Tian , Qiang Guan , Travis Humble , Weiwen Jiang

Quantum Key Distribution (QKD) in principle offers unconditional security based on the laws of physics. Continuous variable (CV) quantum key distribution has the potential for high-key-rate and low-cost implementations using standard…

Quantum Physics · Physics 2021-10-19 Chenyang Li , Li Qian , Hoi-Kwong Lo

Scalable and effective calibration is a fundamental requirement for Low Cost Air Quality Monitoring Systems and will enable accurate and pervasive monitoring in cities. Suffering from environmental interferences and fabrication variance,…

In practical continuous-variable quantum key distribution system using local local oscillator (LLO CV-QKD), the phase noise related to coherent detection and phase-reference pulse intensity that can be locally calibrated at the receiver…

Quantum Physics · Physics 2023-03-22 Yun Shao , Yang Li , Heng Wang , Yan Pan , Yaodi Pi , Yichen Zhang , Wei Huang , Bingjie Xu