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Quantum key distribution (QKD) is a crucial technology for information security in the future. Developing simple and efficient ways to establish QKD among multiple users are important to extend the applications of QKD in communication…

Quantum Physics · Physics 2020-01-15 Xu Liu , Xin Yao , Rong Xue , Heqing Wang , Hao Li , Zhen Wang , Lixing You , Xue Feng , Fang Liu , Kaiyu Cui , Yidong Huang , Wei Zhang

We report on the first real-time implementation of a quantum key distribution (QKD) system using entangled photon pairs that are sent over two free-space optical telescope links. The entangled photon pairs are produced with a type-II…

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

State-of-the-art quantum key distribution systems are based on the BB84 protocol and single photons generated by lasers. These implementations suffer from range limitations and security loopholes, which require expensive adaptation. The use…

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

We propose a high-dimensional quantum key distribution (QKD) protocol that employs temporal correlations of entangled photons. The security of the protocol relies on measurements by Alice and Bob in one of two conjugate bases, implemented…

Quantum Key Distribution (QKD) guarantees the security of communication with quantum physics. Most of widely adopted QKD protocols currently encode the key information with binary signal format---qubit, such as the polarization states.…

Quantum Physics · Physics 2018-01-23 Fumin Wang , Pei Zeng , Xiaoli Wang , Hong Gao , Fuli Li , Pei Zhang

A highly attenuated laser pulse which gives a weak coherent state is widely used in quantum key distribution (QKD) experiments. A weak coherent state has multi-photon components, which opens up a security loophole to the sophisticated…

Quantum Physics · Physics 2008-08-12 Xiongfeng Ma

Entangled photons are crucial resources for quantum information processing. Here, we present an ultrabright polarization-entangled photon source based on a periodically poled lithium niobate waveguide designed for practical quantum…

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

A workflow for evaluation of entanglement source quality is proposed. Based on quantum state density matrices obtained from theoretical models and experimental data, we make an estimate of a potential performance of a quantum entanglement…

Quantum Physics · Physics 2021-04-27 Radim Hošák , Ivo Straka , Ana Predojević , Radim Filip , Miroslav Ježek

Space-based distribution of quantum entanglement will be essential for global quantum networking and secure communications. Modelling and analysis of the performance of satellite entanglement pair distribution is important for the…

Quantum Physics · Physics 2026-02-13 Jasminder S. Sidhu , Sarah E. McCarthy , Cameron Paterson , Daniel K. L. Oi

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…

Quantum communication implementations require efficient and reliable quantum channels. Optical fibers have proven to be an ideal candidate for distributing quantum states. Thus, today's efforts address overcoming issues towards high data…

One of the challenges in practical quantum key distribution is dealing with efficiency mismatch between different threshold single-photon detectors. There are known bounds for the secret key rate for the BB84 protocol with…

Quantum Physics · Physics 2019-03-06 M. K. Bochkov , A. S. Trushechkin

Quantum key distribution (QKD) will most likely be an integral part of any practical quantum network in the future. However, not all QKD protocols can be used in today's networks because of the lack of single-photon emitters and noisy…

Quantum Physics · Physics 2025-10-07 Nitin Jha , Abhishek Parakh , Mahadevan Subramaniam

Multi-photon states from parametric down-conversion can be entangled both in polarization and photon number. Maximal high-dimensional entanglement can be concentrated from these states via photon counting. This makes them natural candidates…

Quantum Physics · Physics 2009-11-07 Gabriel A. Durkin , Christoph Simon , Dik Bouwmeester

Quantum light sources emitting triggered single photons or entangled photon pairs have the potential to boost the performance of quantum key distribution (QKD) systems. Proof-of-principle experiments affirmed these prospects, but further…

High-dimensional quantum key distribution (HDQKD) offers the possibility of high secure-key rate with high photon-information efficiency. We consider HDQKD based on the time-energy entanglement produced by spontaneous parametric…

Quantum Physics · Physics 2015-06-17 Zheshen Zhang , Jacob Mower , Dirk Englund , Franco N. C. Wong , Jeffrey H. Shapiro

We investigate the use of photon number states to identify eavesdropping attacks on quantum key distribution (QKD) schemes. The technique is based on the fact that different photon numbers traverse a channel with different transmittivity.…

Quantum Physics · Physics 2009-11-13 Daryl Achilles , Ekaterina Rogacheva , Alexei Trifonov

We present our approach for sharing photons and assessing resultant four-photon visibility between two distant parties using concatenated entanglement swapping. In addition we determine the corresponding key generation rate and the quantum…

Quantum Physics · Physics 2017-04-05 Aeysha Khalique , Barry C. Sanders