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Quantum key distribution (QKD) is a provably secure way of generating a secret key, which can later be used for encoding and decoding information. In this paper we analyze the effects of an eavesdropper's variable-strength measurements on…

Quantum Physics · Physics 2025-10-01 Yuval Idan , Tal Gofman , Ziv Abelson , Isabelle Cestier , Elad Mentovich , Eliahu Cohen

Quantum key distribution protocols based on the quantum eraser phenomenon offer an operational advantage: automatic identification of matching and mismatching encoding choices through interference, eliminating basis reconciliation. However,…

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

Quantum Key Distribution (QKD) is an innovative quantum communications protocol which exploits the laws of quantum mechanics to generate unconditionally secure cryptographic keying material between two geographically separated parties. The…

The characterization of quantum processes, e.g. communication channels, is an essential ingredient for establishing quantum information systems. For quantum key distribution protocols, the amount of overall noise in the channel determines…

The coding space in quantum communication could be expanded to high-dimensional space by using orbital angular momentum (OAM) states of photons, as both the capacity of the channel and security are enhanced. Here we present a novel approach…

Quantum Physics · Physics 2021-01-01 Ziwen Pan , Jiarui Cai , Chuan Wang

When elementary quantum systems, such as polarized photons, are used to transmit digital information, the uncertainty principle gives rise to novel cryptographic phenomena unachievable with traditional transmission media, e.g. a…

Quantum Physics · Physics 2021-03-23 Charles H. Bennett , Gilles Brassard

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

An application of quantum communications is the transmission of qubits to create shared symmetric encryption keys in a process called Quantum Key Distribution (QKD). Contrary to public-private key encryption, symmetric encryption is safe…

Quantum Physics · Physics 2019-04-25 Tom Vergoossen , Robert Bedington , James A Grieve , Alexander Ling

We propose a method to prepare different non-Poissonian signal pulses from sources of Poissonian photon number distribution using only linear optical elements and threshold photon detectors. This method allows a simple passive preparation…

Quantum Physics · Physics 2015-05-14 Marcos Curty , Tobias Moroder , Xiongfeng Ma , Norbert Lütkenhaus

We propose and demonstrate a quantum key distribution scheme in higher-order $d$-dimensional alphabets using spatial degrees of freedom of photons. Our implementation allows for the transmission of 4.56 bits per sifted photon, while…

Quantum Physics · Physics 2009-11-11 S. P. Walborn , D. S. Lemelle , M. P. Almeida , P. H. Souto Ribeiro

In this paper, we utilize the potential offered by multidimensional separable states (MSS) for secure and simultaneous distributions of keys in a layered network. We present protocols for both quantum and semi-quantum key distribution and…

Quantum Physics · Physics 2023-05-10 Rajni Bala , Sooryansh Asthana , V. Ravishankar

Quantum key distribution (QKD) provides means for unconditional secure key transmission between two distant parties. However, in practical implementations, it suffers from quantum hacking due to device imperfections. Here we propose a…

Quantum Physics · Physics 2014-07-16 Shi-Hai Sun , Mu-Sheng Jiang , Xiang-Chun Ma , Chun-Yan Li , Lin-Mei Liang

Secure communication protocols are becoming increasingly important, e.g. for internet-based communication. Quantum key distribution allows two parties, commonly called Alice and Bob, to generate a secret sequence of 0s and 1s called a key…

Physics Education · Physics 2017-04-05 Antje Kohnle , Aluna Rizzoli

The discrete variables (DV) time-frequency (TF) quantum key distribution (QKD) protocol is a BB84 like protocol, which utilizes time and frequency as complementary bases. As orthogonal modulations, pulse position modulation (PPM) and…

The practical realizations of BB84 quantum key distribution protocol using single-photon or weak coherent states have normally presented low efficiency, in the meaning that most bits sent by Alice are not useful for the final key. In this…

Quantum Physics · Physics 2007-05-23 Fabio Alencar Mendonca , Rubens Viana Ramos

Characterising the input-output photon-number distribution of an unknown optical quantum channel is an important task for many applications in quantum information processing. Ideally, this would require deterministic photon-number sources…

Quantum Physics · Physics 2021-09-14 Emilien Lavie , Ignatius William Primaatmaja , Wen Yu Kon , Chao Wang , Charles Ci Wen Lim

Quantum key distribution (QKD) is a concept of secret key exchange supported by fundamentals of quantum physics. Its perfect realization offers unconditional key security, however, known practical schemes are potentially vulnerable if the…

Quantum Physics · Physics 2014-04-18 I. V. Radchenko , K. S. Kravtsov , S. P. Kulik , S. N. Molotkov

In this Letter, we present quantum secret sharing and secret splitting protocols with single photons running forth and back between the participating parties. The protocol has a high intrinsic efficiency, namely all photons except those…

Quantum Physics · Physics 2009-11-11 Fu-Guo Deng , Hong-Yu Zhou , Gui Lu Long

We consider the security of a system of quantum key distribution (QKD) using only practical devices. Currently, attenuated laser pulses are widely used and considered to be the most practical light source. For the receiver of photons,…

Quantum Physics · Physics 2007-05-23 Masato Koashi