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We propose a new quantum key distribution scheme that is based on the optimum expectation values of maximally entangled Greenberger-Horne-Zeilinger states. Our protocol makes use of the degrees of freedom in continuously variable angles,…

Quantum Physics · Physics 2023-08-21 Hyung S. Choi , Ye Jin Han , Collin Kessinger , Qiaoren Wang

In this paper, we present a flowchart-based description of the decoy-state BB84 quantum key distribution (QKD) protocol and provide a step-by-step, self-contained information-theoretic security proof for this protocol within the universal…

Quantum Physics · Physics 2025-05-27 Akihiro Mizutani , Toshihiko Sasaki , Go Kato

Quantum key distribution (QKD) offers the promise of absolutely secure communications. However, proofs of absolute security often assume perfect implementation from theory to experiment. Thus, existing systems may be prone to insidious…

Quantum Physics · Physics 2014-06-23 Samuel L. Braunstein , Stefano Pirandola

The security of quantum key distribution (QKD) is evaluated based on the secrecy of Alice's key and the correctness of the keys held by Alice and Bob. A practical method for ensuring correctness is known as error verification, in which…

Quantum Physics · Physics 2025-12-04 Toyohiro Tsurumaru , Akihiro Mizutani , Toshihiko Sasaki

We show the unconditional security of decoy-state method quantum cryptography with whatever intensity error pattern provided that the error is not too large. Our result immediately applies to the existing experimental data. Our result is…

Quantum Physics · Physics 2013-05-29 Xiang-Bin Wang , Cheng-Zhi Peng , Jun Zhang , Jian-Wei Pan

Quantum key distribution (QKD) promises everlasting security based on the laws of physics. Most common protocols are grouped into two distinct categories based on the degrees of freedom used to carry information, which can be either…

Quantum Physics · Physics 2024-02-28 Jasminder S. Sidhu , Rocco Maggi , Saverio Pascazio , Cosmo Lupo

In this paper, we prove that the unconditionally secure key can be surprisingly extracted from {\it multi}-photon emission part in the photon polarization-based QKD. One example is shown by explicitly proving that one can indeed generate an…

Quantum Physics · Physics 2009-11-10 Kiyoshi Tamaki , Hoi-Kwong Lo

The quantum key distribution (QKD), guaranteed by the principle of quantum physics, is a promising solution for future secure information and communication technology. However, device imperfections compromise the security of real-life QKD…

Quantum Physics · Physics 2022-09-14 Ye Chen , Chunfeng Huang , Zihao Chen , Wenjie He , Chengxian Zhang , Shihai Sun , Kejin Wei

It is well known that no quantum bit commitment protocol is unconditionally secure. Nonetheless, there can be non-trivial upper bounds on both Bob's probability of correctly estimating Alice's commitment and Alice's probability of…

Quantum Physics · Physics 2007-05-23 R. W. Spekkens , T. Rudolph

In contrast to classical public-key cryptosystems, where the security of encoded messages relies on on computational assumptions, Quantum Key Distribution (QKD) enables two distant parties to establish a shared secret key that, when…

Security proofs of quantum key distribution (QKD) typically assume that the devices of the legitimate users are perfectly shielded from the eavesdropper. This assumption is, however, very hard to meet in practice, and thus the security of…

Quantum Physics · Physics 2018-09-05 Weilong Wang , Kiyoshi Tamaki , Marcos Curty

Security proof of practical quantum key distribution (QKD) has attracted a lot of attentions in recent years. Most of real-life QKD implementations are based on phase-coding BB84 protocol, which usually uses Unbalanced Mach-Zehnder…

Quantum Physics · Physics 2010-09-08 Hong-Wei Li , Zhen-Qiang Yin , Zheng-Fu Han , Wan-Su Bao , Guang-Can Guo

Quantum states cannot be cloned. I show how to extend this property to classical messages encoded using quantum states, a task I call "uncloneable encryption." An uncloneable encryption scheme has the property that an eavesdropper Eve not…

Quantum Physics · Physics 2007-05-23 Daniel Gottesman

Quantum key distribution (QKD) promises information-theoretic security based on quantum mechanics, but practical implementations face security vulnerabilities due to device imperfections. Recent advances have separately addressed source and…

Quantum Physics · Physics 2025-07-08 Guillermo Currás-Lorenzo , Margarida Pereira , Shlok Nahar , Devashish Tupkary

Quantum key distribution(QKD) is one of the most significant areas in quantum information theory. For nearly four decades, substantial QKD schemes are developed. In early years, the security of QKD protocols is depend on switching different…

Quantum Physics · Physics 2022-12-12 Hao Shu

We introduce a new quantum key distribution protocol that uses d-level quantum systems to encode an alphabet with c letters. It has the property that the error rate introduced by an intercept-and-resend attack tends to one as the numbers c…

Quantum Physics · Physics 2009-10-15 Stephen Brierley

The existing theory of decoy-state quantum cryptography assumes the exact control of each states from Alice's source. Such exact control is impossible in practice. We develop the theory of decoy-state method so that it is unconditionally…

Quantum Physics · Physics 2009-11-13 Xiang-Bin Wang , C. -Z. Peng , J. Zhang , L. Yang , Jian-Wei Pan

Quantum Key Distribution (QKD) is revolutionizing cryptography by promising information-theoretic security through the immutable laws of quantum mechanics. Yet, the challenge of transforming these idealized security models into practical,…

Quantum Physics · Physics 2026-02-24 Nitin Jha , Abhishek Parakh , Mahadevan Subramaniam

Coherent one-way quantum key distribution (COW-QKD) has been widely investigated, and even been deployed in real-world quantum network. However, the proposal of the zero-error attack has critically undermined its security guarantees, and…

Quantum Physics · Physics 2026-01-13 Xiao-Yu Cao , Xiao-Ran Sun , Ming-Yang Li , Yu-Shuo Lu , Hua-Lei Yin , Zeng-Bing Chen

We show how weak non-linearities can be used in a device-independent quantum key distribution (QKD) protocol using generalized two-mode Schr\"odinger cat states. The QKD protocol is therefore shown to be secure against collective attacks…

Quantum Physics · Physics 2015-08-12 Curtis J. Broadbent , Kevin Marshall , Christian Weedbrook , John C. Howell