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The ultimate goal of quantum information science is to build a global quantum network, which enables quantum resources to be distributed and shared between remote parties. Such quantum network can be realized by all fiber elements, which…

Quantum Physics · Physics 2016-10-19 Yin-Hai Li Zhi-Yuan Zhou , Zhao-Huai Xu , Li-Xin Xu , Bao-Sen Shi , Guang-Can Guo

The reliable distribution of high-dimensional entangled quantum states, an important resource in quantum technologies, through optical fibre networks is challenging due to the need to maintain coherence across multiple modes. Here we…

We create pairs of non-degenerate time-bin entangled photons at telecom wavelengths with ultra-short pump pulses. Entanglement is shown by performing Bell kind tests of the Franson type with visibilities of up to 91%. As time-bin…

We report that entangled pairs of quantum clocks (non-degenerate quantum bits) can be used as a specialized detector for precisely measuring difference of proper-times that each constituent quantum clock experiences. We describe why the…

Quantum Physics · Physics 2009-11-06 W. Y. Hwang , D. Ahn , S. W. Hwang , Y. D. Han

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

In recent years there has been a great deal of focus on a globe-spanning quantum network, including linked satellites for applications ranging from quantum key distribution to distributed sensors and clocks. In many of these schemes,…

Generating entanglement between distributed network nodes is a prerequisite for the quantum internet. Entanglement distribution protocols based on high-dimensional photonic qudits enable the simultaneous generation of multiple entangled…

Quantum Physics · Physics 2024-01-15 Xiaoyu Liu , Niv Bharos , Liubov Markovich , Johannes Borregaard

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

Entangled photons play a pivotal role in the distribution of quantum information in quantum networks. However, the frequency bands for optimal transmission and storage of photons are not necessarily the same. Here we experimentally…

Quantum Physics · Physics 2012-02-07 Sven Ramelow , Alessandro Fedrizzi , Andreas Poppe , Nathan K. Langford , Anton Zeilinger

The security analysis of quantum key distribution is difficult to perform when there is efficiency mismatch between various threshold detectors involved in an experimental setup. Even the verification that the device actually performs in…

Quantum Physics · Physics 2017-05-01 Yanbao Zhang , Norbert Lutkenhaus

We demonstrate a point-to-point clock synchronization protocol based on bidirectionally propagating photons generated in a single spontaneous parametric down-conversion (SPDC) source. Tight timing correlations between photon pairs are used…

Quantum Physics · Physics 2022-06-01 Jianwei Lee , Lijiong Shen , Adrian Nugraha Utama , Christian Kurtsiefer

Quantum computing and quantum communication, have been greatly developed in recent years and expected to contribute to quantum internet technologies, including cloud quantum computing and unconditionally secure communication. However,…

Quantum key distribution (QKD) enables two parties to establish a secret key over a potentially hostile channel by exchanging photonic quantum states, relying on the fact that it is impossible for an eavesdropper to tap the quantum channel…

Quantum Physics · Physics 2011-10-24 Jacob Mower , F. N. C. Wong , Jeff H. Shapiro , Dirk Englund

We report the security analysis of time-coding quantum key distribution protocols. The protocols make use of coherent single-photon pulses. The key is encoded in the photon time-detection. The use of coherent superposition of states allows…

Quantum Physics · Physics 2011-09-29 Thierry Debuisschert , Simon Fossier

In ``Distributed quantum sensing with mode-entangled spin-squeezed atomic states" Nature (2022), Malia et. al. claim to improve the precision of a network of clocks by using entanglement. In particular, by entangling a clock network with up…

Quantum Physics · Physics 2023-05-04 Liam P. McGuinness

We report the first experimental realization of entanglement swapping over large distances in optical fibers. Two photons separated by more than two km of optical fibers are entangled, although they never directly interacted. We use two…

Quantum Physics · Physics 2009-11-10 H. de Riedmatten , I. Marcikic , J. A. W. van Houwelingen , W. Tittel , H. Zbinden , N. Gisin

Practical quantum networking architectures are crucial for scaling the connection of quantum resources. Yet quantum network testbeds have thus far underutilized the full capabilities of modern lightwave communications, such as flexible-grid…

Entanglement shared between distant parties is a key resource in quantum networks. However, photon losses in quantum channels significantly reduce the success probability of entanglement sharing, which scales quadratically with the channel…

Quantum Physics · Physics 2024-05-08 Wan Zo , Bohdan Bilash , Donghwa Lee , Yosep Kim , Hyang-Tag Lim , Kyunghwan Oh , Syed M. Assad , Yong-Su Kim

Entanglement between stationary quantum memories and photonic channels is the essential resource for future quantum networks. Together with entanglement distillation it will enable for efficient distribution of quantum states. Here we…

Quantum information technology has the potential to revolutionize computing, communications, and security. To fully realize its potential, quantum processors with millions of qubits are needed, which is still far from being accomplished.…

Quantum Physics · Physics 2023-12-12 Nicholas Skjellum , Mohamed Shaban , Muhammad Ismail