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Quantum key distribution (QKD) theoretically offers unconditional security. Unfortunately, the gap between theory and practice threatens side-channel attacks on practical QKD systems. Many well-known QKD protocols use weak coherent laser…

In the burgeoning field of quantum computing, the precise design and optimization of quantum pulses are essential for enhancing qubit operation fidelity. This study focuses on refining the pulse engineering techniques for superconducting…

Quantum Physics · Physics 2024-09-13 Annika S. Wiening , Joern Bergendahl , Vicente Leyton-Ortega , Peter Nalbach

The idea of post-measurement coincidence pairing simplifies substantially long-distance, repeater-like quantum key distribution (QKD) by eliminating the need for tracking the differential phase of the users' lasers. However, optical…

Quantum Physics · Physics 2024-07-23 Chengfang Ge , Lai Zhou , Jinping Lin , Hua-Lei Yin , Qiang Zeng , Zhiliang Yuan

We propose a post-selection technique, based on quantum error detection, for quantum key distribution (QKD) systems that run over quantum repeaters with encoding. In such repeaters, quantum error correction techniques are used for…

Quantum Physics · Physics 2021-01-04 Yumang Jing , Daniel Alsina Leal , Mohsen Razavi

Quantum correlations may violate the Bell inequalities. Most of the experimental schemes confirming this prediction have been realized in all-optical Bell tests suffering from the detection loophole. Experiment which closes this loophole…

Quantum Physics · Physics 2011-09-23 Magdalena Stobińska , Pavel Sekatski , Adam Buraczewski , Nicolas Gisin , Gerd Leuchs

The measurement of time durations or instants of ocurrence of events has been frequently modelled ``operationally'' by coupling the system of interest to a ``clock''. According to several of these models the operational approach is limited…

Quantum Physics · Physics 2009-11-07 D. Alonso , R. Sala Mayato , J. G. Muga

In free-space quantum key distribution (QKD), the sensitivity of the receiver's detector channels may depend differently on the spatial mode of incoming photons. Consequently, an attacker can control the spatial mode to break security. We…

A pulsed source of entangled photons is desirable for some applications. Yet, such a source has intrinsic problems arising from the simultaneous arrival of the signal and noise photons to the detectors. These problems are analyzed and…

Optics · Physics 2015-06-18 Mónica B. Agüero , Alejandro A. Hnilo , Marcelo G. Kovalsky

Entanglement is a unique property of quantum systems and an essential resource for many quantum technologies. The ability to transfer or swap entanglement between systems is an important protocol in quantum information science. Entanglement…

Quantum Physics · Physics 2022-02-23 Sofiane Merkouche , Valérian Thiel , Alex O. C. Davis , Brian J. Smith

Superconducting quantum circuits, such as the superconducting phase qubit, have multiple quantum states that can interfere with ideal qubit operation. The use of multiple frequency control pulses, resonant with the energy differences of the…

Quantum Physics · Physics 2013-05-29 Anne M. Forney , Steven R. Jackson , Frederick W. Strauch

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…

Postselected quantum computation is distinguished from regular quantum computation by accepting the output only if measurement outcomes satisfy predetermined conditions. The output must be accepted with nonzero probability. Methods for…

Quantum Physics · Physics 2007-05-23 E. Knill

We investigate a quantum key distribution (QKD) scheme which utilizes a biased basis choice in order to increase the efficiency of the scheme. The optimal bias between the two measurement bases, a more refined error analysis, and finite key…

Quantum Physics · Physics 2012-10-25 C. Erven , X. Ma , R. Laflamme , G. Weihs

Device-independent quantum key distribution (DI-QKD) leverages nonlocal correlations to establish cryptographic keys between two honest parties while making minimal assumptions about the underlying systems. The security of DI-QKD is…

Quantum Physics · Physics 2026-05-20 Pritam Roy , Souradeep Sasmal , Subhankar Bera , Shashank Gupta , Arup Roy , A. S. Majumdar

A common way to manipulate a quantum system, for example spins or artificial atoms, is to use properly tailored control pulses. In order to accomplish quantum information tasks before coherence is lost, it is crucial to implement the…

Existing security proofs of quantum key distribution (QKD) suffer from two fundamental weaknesses. First, memory attacks have emerged as an important threat to the security of even device-independent quantum key distribution (DI-QKD),…

Quantum Physics · Physics 2020-07-14 Marcos Curty , Hoi-Kwong Lo

Clock synchronization is critical for maintaining low error rates in quantum key distribution. Here, we describe how a frequency mismatch between the transmitter and receiver clocks affects the quantum bit error rate in quantum key…

Quantum Physics · Physics 2026-05-27 Loïc Millet , Boris Korzh , Rob Thew , Gianluca Boso

The bases traditionally used for quantum key distribution (QKD) are a 0 or pi/2 polarization or alternatively a 0 or pi/2 phase measured by interferometry. We introduce a new set of bases, i.e. pulses sent in either a frequency or time…

Quantum Physics · Physics 2007-05-23 S. F. Yelin , Bing C. Wang

In this paper, we investigate limitations imposed by sequential attacks on the performance of a differential-phase-shift (DPS) quantum key distribution (QKD) protocol with weak coherent pulses. Specifically, we analyze a sequential attack…

Quantum Physics · Physics 2008-10-12 Hipolito Gomez-Sousa , Marcos Curty

A protocol with the potential of beating the existing distance records for conventional quantum key distribution (QKD) systems is proposed. It borrows ideas from quantum repeaters by using memories in the middle of the link, and that of…

Quantum Physics · Physics 2014-09-02 Christiana Panayi , Mohsen Razavi , Xiongfeng Ma , Norbert Lütkenhaus