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In this paper we demonstrate an active polarization drift compensation scheme for optical fibres employed in a quantum key distribution experiment with polarization encoded qubits. The quantum signals are wavelength multiplexed in one fibre…

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…

We present two protocols for the single-photon entanglement concentration. With the help of the 50:50 beam splitter, variable beam splitter and an auxiliary photon, we can concentrate a less-entangled single-photon state into a maximally…

Quantum Physics · Physics 2012-10-01 Lan Zhou

Quantum network sensing shows potential to enhance the estimation precision for functions of spatially distributed parameters beyond the shot noise limit. The key resource required for this task is possibly multi-partite quantum…

Quantum Physics · Physics 2025-05-16 Yoshihiro Ueda , Makoto Ishihara , Wojciech Roga , Masahiro Takeoka

Error-free transmission (EFT) of quantum information is a crucial ingredient in quantum communication network. To overcome the unavoidable decoherence in noisy channel, to date, many efforts have focused on faithfully transmitting one state…

Quantum Physics · Physics 2010-05-04 Xian-Min Jin , Zhen-Huan Yi , Bin Yang , Fei Zhou , Tao Yang , Cheng-Zhi Peng

Quantum-cryptography key distribution (QCKD) experiments have been recently reported using polarization-entangled photons. However, in any practical realization, quantum systems suffer from either unwanted or induced interactions with the…

Quantum Physics · Physics 2009-11-07 S. Castelletto , I. P. Degiovanni , M. L. Rastello

We propose an efficient quantum key distribution scheme based on entanglement. The sender chooses pairs of photons in one of the two equivalent nonmaximally entangled states randomly, and sends a sequence of photons from each pair to the…

Quantum Physics · Physics 2009-11-07 Peng Xue , Chuan-Feng Li , Guang-Can Guo

We present a quantum repeater protocol for distributing entanglement over long distances, where a dedicated communication stage enables trial rates not limited by the travel time between repeater nodes. To accomplish this, each node…

Quantum Physics · Physics 2025-04-25 Adam Kinos , Andreas Walther , Stefan Kröll , Lars Rippe

Understanding the distribution of quantum entanglement over many parties is a fundamental challenge of quantum physics and is of practical relevance for several applications in the field of quantum information. Here we use methods from…

In this Letter, the generation of 1.5 {\mu}m discrete frequency entangled two-photon state is realized based on a piece of commercial polarization maintaining fiber (PMF). It is connected with a polarization beam splitter to realize a…

Quantum Physics · Physics 2014-04-01 Qiang Zhou , Wei Zhang , Chenzhi Yuan , Yidong Huang , Jiangde Peng

Entanglement distribution is key to the success of secure communication schemes based on quantum mechanics, and there is a strong need for an ultimate architecture able to overcome the limitations of recent proposals such as those based on…

Quantum Physics · Physics 2015-09-10 Alexander Streltsov , Remigiusz Augusiak , Maciej Demianowicz , Maciej Lewenstein

We investigate entanglement distribution in pure-state quantum networks. We consider the case when non-maximally entangled two-qubit pure states are shared by neighboring nodes of the network. For a given pair of nodes, we investigate how…

Quantum Physics · Physics 2009-01-19 S. Perseguers , J. Wehr , A. Acin , M. Lewenstein , J. I. Cirac

Quantum networking can be realized by distributing pairs of entangled qubits between remote quantum processing nodes. Devoted communication qubits within each node can naturally interface with photons which bus quantum information between…

Quantum Physics · Physics 2025-06-09 Ely Novakoski , Jungsang Kim

Quantum information is often carried in the frequency and polarization degrees of freedom (DoFs) in single photons and entangled photons. We demonstrate a new approach to couple and decouple the frequency and polarization DoFs of broadband…

Quantum Physics · Physics 2023-11-27 Arash Riazi , Eric Y. Zhu , Dan Xu , Li Qian

Quantum entanglement across spatially separated network nodes is conventionally established through the distribution of photons from a common source or via entanglement swapping that relies on Bell-state measurements and pre-shared…

Quantum Physics · Physics 2026-01-06 Sören Arlt , Mario Krenn , Xuemei Gu

Entanglement distribution between distant parties is one of the most important and challenging tasks in quantum communication. Distribution of photonic entangled states using optical fiber links is a fundamental building block towards…

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…

The binary (one-bit-per-photon) encoding that most existing quantum key distribution (QKD) protocols employ puts a fundamental limit on their achievable key rates, especially under high channel loss conditions associated with long-distance…

We demonstrate polarization entanglement in highly non-degenerate photon pairs, generated through Type-0 spontaneous parametric down conversion (SPDC) using bulk periodically poled Lithium Niobate (PPLN) crystals. Through the utilization of…

Quantum Physics · Physics 2024-11-21 Sungeun Oh , Thomas Jennewein

High-dimensional entanglement provides unique ways of transcending the limitations of current approaches in quantum information processing, quantum communications based on qubits. The generation of time-frequency qudit states offer…