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We propose and theoretically analyze a teleportation-based scheme for high-fidelity noiseless quantum amplification of coherent states of light. In our approach, the probabilistic noiseless quantum amplification operation is encoded into a…

Quantum Physics · Physics 2025-08-26 Jaromír Fiurášek

We establish a security proof of frequency-time coding quantum key distribution (FT-QKD) protocol by showing its connection to the squeezed state quantum key distribution protocol, which has been proven to be unconditionally secure. We also…

Quantum Physics · Physics 2015-03-18 Bing Qi

Significant work has been done to develop quantum satellites, which generate entangled pairs in space and distribute them to ground stations separated some distance away. The reverse uplink case, where pairs are generated on the ground and…

Quantum Physics · Physics 2025-06-30 S. Srikara , Hudson Leone , Alexander S. Solnstev , Simon J. Devitt

Communication in quantum networks suffers notoriously from photon loss. Resulting errors can be mitigated with a suitable measurement herald at the receiving node. However, waiting for a herald and communicating the measurement result back…

Quantum Physics · Physics 2025-12-11 Gianvito Chiarella , Tobias Frank , Leart Zuka , Pau Farrera , Gerhard Rempe

Quantum key distribution (QKD) offers an unconditionally secure means of communication based on the laws of quantum mechanics. Currently, a major challenge is to achieve a QKD system with a 40 dB channel loss, which is required if we are to…

Several vulnerabilities of single photon detectors have recently been exploited to compromise the security of quantum key distribution (QKD) systems. In this letter we report the first proof-of-principle implementation of a new quantum key…

Quantum Physics · Physics 2013-10-03 Allison Rubenok , Joshua A. Slater , Philip Chan , Itzel Lucio-Martinez , Wolfgang Tittel

Two-photon processes are crucial in applications like microscopy and microfabrication, but their low cross-section requires intense illumination and limits, e.g., the penetration depth in nonlinear microscopy. Entangled states have been…

Using polarization-entangled photons from spontaneous parametric downconversion, we have implemented Ekert's quantum cryptography protocol. The near-perfect correlations of the photons allow the sharing of a secret key between two parties.…

Quantum Physics · Physics 2009-10-31 D. S. Naik , C. G. Peterson , A. G. White , A. J. Berglund , P. G. Kwiat

An ideal controlled-NOT gate followed by projective measurements can be used to identify specific Bell states of its two input qubits. When the input qubits are each members of independent Bell states, these projective measurements can be…

Quantum Physics · Physics 2016-11-18 T. B. Pittman , M. M. Donegan , M. J. Fitch , B. C. Jacobs , J. D. Franson , P. Kok , H. Lee , J. P. Dowling

Entanglement concentration is a critical technique to prevent degraded fidelity and security in long-distance quantum communication. We propose novel practical entanglement concentration protocols (ECPs) for less-entangled Bell and…

Quantum Physics · Physics 2023-04-05 Gui-Long Jiang , Wen-Qiang Liu , Hai-Rui Wei

Entanglement generation between distant nodes is a fundamental process in distributed quantum information processing. Qudits, high-dimensional quantum states, are promising candidates for enhancing entanglement distribution capabilities.…

Quantum Physics · Physics 2026-03-26 Kazufumi Tanji , Hikaru Shimizu , Masahiro Takeoka

One of the most fascinating aspects of quantum networks is their capability to distribute entanglement as a nonlocal communication resource. In a first step, this requires network-ready devices that can generate and store entangled states.…

Measurement-device-independent quantum key distribution (MDI-QKD) removes all detector side channels and enables secure QKD with an untrusted relay. It is suitable for building a star-type quantum access network, where the complicated and…

Modular networks are a promising paradigm for increasingly complex quantum devices based on the ability to transfer qubits and generate entanglement between modules. These tasks require a low-loss, high-speed intermodule link that enables…

Decoherence is detrimental to quantum key distribution (QKD) over large distances. One of the proposed solutions is to use quantum repeaters, which divide the total distance between the users into smaller segments to minimise the effects of…

Generating quantum entanglement is not only an important scientific endeavor, but will be essential to realizing quantum-enhanced technologies, in particular, quantum-enhanced measurements with precision beyond classical limits. We…

Quantum Physics · Physics 2011-10-24 Jonathan C. F. Matthews , Alberto Politi , Damien Bonneau , Jeremy L. O'Brien

Quantum key distribution (QKD offers a long-term solution to establish information-theoretically secure keys between two distant users. In practice, with a careful characterization of quantum sources and the decoy-state method,…

Entangled states of photons form the foundation of quantum communication, computation, and metrology. Yet their generation remains fundamentally constrained: in the absence of intrinsic photon-photon interactions, the generation of such…

Entangled photons are a crucial resource for quantum communication and linear optical quantum computation. Unfortunately, the applicability of many photon-based schemes is limited due to the stochastic character of the photon sources.…

Quantum Physics · Physics 2012-02-07 Stefanie Barz , Gunther Cronenberg , Anton Zeilinger , Philip Walther

Addition of single photons to two-mode-squeezed-vacuum states has the effect of distilling quantum entanglement, and, when deployed in quantum key distribution, should lead also to an increase in the secret key rate. However, the extraction…

Quantum Physics · Physics 2025-07-25 Hao Jeng , Ping Koy Lam , Syed M. Assad