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We consider a generalisation of Ekert's entanglement-based quantum cryptographic protocol where qubits are replaced by qu$N$its (i.e., N-dimensional systems). In order to study its robustness against optimal incoherent attacks, we derive…

Quantum Physics · Physics 2009-11-10 Thomas Durt , Dagomir Kaszlikowski , Jing-Ling Chen , L. C. Kwek

We devise a simple modification that essentially doubles the efficiency of the BB84 quantum key distribution scheme proposed by Bennett and Brassard. We also prove the security of our modified scheme against the most general eavesdropping…

Quantum Physics · Physics 2016-09-08 Hoi-Kwong Lo , H. F. Chau , M. Ardehali

Quantum key distribution (QKD) allows two remote users to establish a secret key in the presence of an eavesdropper. The users share quantum states prepared in two mutually-unbiased bases: one to generate the key while the other monitors…

Quantum Physics · Physics 2018-05-03 Nurul T. Islam , Charles Ci Wen Lim , Clinton Cahall , Jungsang Kim , Daniel J. Gauthier

The realization of effective quantum error correction protocols remains a central challenge in the development of scalable quantum computers. Employing high-dimensional quantum systems (qudits) can offer more hardware-efficient protocols…

Quantum Physics · Physics 2025-03-18 Sumin Lim , Mikhail V. Vaganov , Junjie Liu , Arzhang Ardavan

Fast qubit reset is essential for qubit reuse in the noisy intermediate-scale quantum computing era, yet it conflicts with the weak decoherence required for high-fidelity computation. We solve the time-optimal reset problem for a…

Quantum Physics · Physics 2026-04-24 Hong-Bo Huang , Hui Dong

Quantum key distribution is a cornerstone of quantum cryptography, enabling secure communication through the principles of quantum mechanics. In reality, most practical implementations rely on the decoy-state method to ensure security…

Quantum Physics · Physics 2024-11-04 Zitai Xu , Yizhi Huang , Xiongfeng Ma

A new scheme of quantum coding is presented. The scheme concerns the quantum states to which Schumacher's compression does not apply. It is shown that two qubits can be encoded in a single qutrit in such a way that one can faithfully…

Quantum Physics · Physics 2009-11-10 Andrzej Grudka , Antoni Wojcik

A critical step in experimental quantum information processing (QIP) is to implement control of quantum systems protected against decoherence via informational encodings, such as quantum error correcting codes, noiseless subsystems and…

Quantum Physics · Physics 2009-09-13 P. Cappellaro , J. S. Hodges , T. F. Havel , D. G. Cory

We present a one-shot method for preparing pure entangled states between a sender and a receiver at a minimal cost of entanglement and quantum communication. In the case of preparing unentangled states, an earlier paper showed that a…

Quantum Physics · Physics 2007-05-23 Anura Abeyesinghe , Patrick Hayden , Graeme Smith , Andreas Winter

We consider two quantum cryptographic schemes relying on encoding the key into qudits, i.e. quantum states in a d-dimensional Hilbert space. The first cryptosystem uses two mutually unbiased bases (thereby extending the BB84 scheme), while…

Quantum Physics · Physics 2009-11-07 Nicolas J. Cerf , Mohamed Bourennane , Anders Karlsson , Nicolas Gisin

Entanglement based quantum communication offers an increased level of security in practical secret shared key distribution. One of the fundamental principles enabling this security -- the fact that interfering with one photon will destroy…

To increase dramatically the distance and the secure key generation rate of quantum key distribution (QKD), the idea of quantum decoys--signals of different intensities--has recently been proposed. Here, we present the first experimental…

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

We present two new schemes for quantum key distribution (QKD) that neither require entanglement nor an ideal single-photon source, making them implementable with commercially available single-photon sources. These protocols are shown to be…

Quantum Physics · Physics 2025-05-13 Arindam Dutta , Anirban Pathak

With the rapid development of quantum computing, classical cryptography systems are increasingly vulnerable to security threats, thereby highlighting the urgency of constructing architectures that are resilient to quantum computing attacks.…

Cryptography and Security · Computer Science 2026-02-13 Xiaoming Chen , Haoze Chen , Fei Xu , Meifeng Gao , Jianguo Xie , Cheng Ye , An Hua , Shichang Jiang , Jiao Zhao , Minghan Li , Feilong Li , Yajun Miao , Wei Qi

Recently, Chau introduced an experimentally feasible qudit-based quantum-key-distribution (QKD) scheme. In that scheme, one bit of information is phase encoded in the prepared state in a $2^n$-dimensional Hilbert space in the form…

Quantum Physics · Physics 2017-02-15 H. F. Chau , Qinan Wang , Cardythy Wong

Due to its ability to tolerate high channel loss, decoy-state quantum key distribution (QKD) has been one of the main focuses within the QKD community. Notably, several experimental groups have demonstrated that it is secure and feasible…

Quantum Physics · Physics 2014-02-12 Charles Ci Wen Lim , Marcos Curty , Nino Walenta , Feihu Xu , Hugo Zbinden

We study a novel protocol for reference frame independent (RFI) quantum key distribution (QKD) using six states for Alice and four states for Bob, while previous RFI protocols require a six state analyzer for Bob. Our protocol can generate…

Quantum key distribution (QKD) is the most widely studied quantum cryptographic model that exploits quantum effects to achieve information-theoretically secure key establishment. Conventional QKD contains public classical post-processing…

Quantum Physics · Physics 2026-01-07 Zixuan Hu , Zhenyu Li

Near-term quantum computations are limited by high error rates, the scarcity of qubits and low qubit connectivity. Increasing support for mid-circuit measurements and qubit reset in near-term quantum computers enables qubit reuse that may…

Quantum Physics · Physics 2023-08-02 Sebastian Brandhofer , Ilia Polian , Kevin Krsulich

From the output produced by a memoryless deletion channel with a uniformly random input of known length $n$, one obtains a posterior distribution on the channel input. The difference between the Shannon entropy of this distribution and that…

Cryptography and Security · Computer Science 2020-03-27 Arash Atashpendar