scholarly journals Coupling of a quantum memory and telecommunication wavelength photons for high-rate entanglement distribution in quantum repeaters

2021 ◽  
Author(s):  
Kyoko Mannami ◽  
Takeshi Kondo ◽  
Tomoki Tsuno ◽  
Takuto Miyashita ◽  
Daisuke Yoshida ◽  
...  
2020 ◽  
Vol 18 (05) ◽  
pp. 2050026
Author(s):  
Daisuke Yoshida ◽  
Kazuya Niizeki ◽  
Shuhei Tamura ◽  
Tomoyuki Horikiri

Quantum repeaters, which are indispensable for long-distance quantum communication, are necessary for extending the entanglement from short distance to long distance; however, high-rate entanglement distribution, even between adjacent repeater nodes, has not been realized. In a recent work by [C. Jones et al., New J. Phys. 18 (2016) 083015], the entanglement distribution rate between adjacent repeater nodes was calculated for a plurality of quantum dots, nitrogen-vacancy centers in diamond, and trapped ions adopted as quantum memories inside the repeater nodes. Considering practical use, arranging a plurality of quantum memories becomes so difficult with the state-of-the art technology. It is desirable that high-rate entanglement distribution is realized with as few memory crystals as possible. Here, we propose new entanglement distribution scheme with one quantum memory based on the atomic frequency comb which enables temporal multimode operation with one crystal. The adopted absorptive-type quantum memory degrades the difficulty of multimode operation compared with the previously investigated quantum memories directly generating spin-photon entanglement. It is shown that this scheme improves the distribution rate by nearly two orders of magnitude compared with the result in [C. Jones et al., New J. Phys. 18 (2016) 083015] and the experimental implementation is close by utilizing state-of-the-art technology.


Quantum ◽  
2018 ◽  
Vol 2 ◽  
pp. 93 ◽  
Author(s):  
F. Kimiaee Asadi ◽  
N. Lauk ◽  
S. Wein ◽  
N. Sinclair ◽  
C. O'Brien ◽  
...  

We present a quantum repeater scheme that is based on individual erbium and europium ions. Erbium ions are attractive because they emit photons at telecommunication wavelength, while europium ions offer exceptional spin coherence for long-term storage. Entanglement between distant erbium ions is created by photon detection. The photon emission rate of each erbium ion is enhanced by a microcavity with high Purcell factor, as has recently been demonstrated. Entanglement is then transferred to nearby europium ions for storage. Gate operations between nearby ions are performed using dynamically controlled electric-dipole coupling. These gate operations allow entanglement swapping to be employed in order to extend the distance over which entanglement is distributed. The deterministic character of the gate operations allows improved entanglement distribution rates in comparison to atomic ensemble-based protocols. We also propose an approach that utilizes multiplexing in order to enhance the entanglement distribution rate.


2021 ◽  
Vol 127 (22) ◽  
Author(s):  
Mohsen Falamarzi Askarani ◽  
Antariksha Das ◽  
Jacob H. Davidson ◽  
Gustavo C. Amaral ◽  
Neil Sinclair ◽  
...  

2016 ◽  
Vol 93 (3) ◽  
Author(s):  
Pierre Jobez ◽  
Nuala Timoney ◽  
Cyril Laplane ◽  
Jean Etesse ◽  
Alban Ferrier ◽  
...  

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Michał Lipka ◽  
Mateusz Mazelanik ◽  
Adam Leszczyński ◽  
Wojciech Wasilewski ◽  
Michał Parniak

AbstractHigh-rate generation of hybrid photon-matter entanglement remains a fundamental building block of quantum network architectures enabling protocols such as quantum secure communication or quantum distributed computing. While a tremendous effort has been made to overcome technological constraints limiting the efficiency and coherence times of current systems, an important complementary approach is to employ parallel and multiplexed architectures. Here we follow this approach experimentally demonstrating the generation of bipartite polarization-entangled photonic states across more than 500 modes, with a programmable delay for the second photon enabled by qubit storage in a wavevector-multiplexed cold-atomic quantum memory. We demonstrate Clauser, Horne, Shimony, Holt inequality violation by over 3 standard deviations, lasting for at least 45 μs storage time for half of the modes. The ability to shape hybrid entanglement between the polarization and wavevector degrees of freedom provides not only multiplexing capabilities but also brings prospects for novel protocols.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Laszlo Gyongyosi ◽  
Sandor Imre

AbstractCrucial problems of the quantum Internet are the derivation of stability properties of quantum repeaters and theory of entanglement rate maximization in an entangled network structure. The stability property of a quantum repeater entails that all incoming density matrices can be swapped with a target density matrix. The strong stability of a quantum repeater implies stable entanglement swapping with the boundness of stored density matrices in the quantum memory and the boundness of delays. Here, a theoretical framework of noise-scaled stability analysis and entanglement rate maximization is conceived for the quantum Internet. We define the term of entanglement swapping set that models the status of quantum memory of a quantum repeater with the stored density matrices. We determine the optimal entanglement swapping method that maximizes the entanglement rate of the quantum repeaters at the different entanglement swapping sets as function of the noise of the local memory and local operations. We prove the stability properties for non-complete entanglement swapping sets, complete entanglement swapping sets and perfect entanglement swapping sets. We prove the entanglement rates for the different entanglement swapping sets and noise levels. The results can be applied to the experimental quantum Internet.


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