scholarly journals Passively stable distribution of polarisation entanglement over 192 km of deployed optical fibre

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Sören Wengerowsky ◽  
Siddarth Koduru Joshi ◽  
Fabian Steinlechner ◽  
Julien R. Zichi ◽  
Bo Liu ◽  
...  
Keyword(s):  
Quantum Key Distribution ◽  
Stable Distribution ◽  
Dispersion Compensation ◽  
Chromatic Dispersion ◽  
Bell State ◽  
Long Distance ◽  
Quantum Networks ◽  
Two Photon ◽  
Photon Pairs ◽  
Entangled Photon Pairs

AbstractQuantum key distribution (QKD) based on entangled photon pairs holds the potential for repeater-based quantum networks connecting clients over long distance. We demonstrate long-distance entanglement distribution by means of polarisation-entangled photon pairs through two successive deployed 96 km-long telecommunications fibres in the same submarine cable. One photon of each pair was detected directly after the source, while the other travelled the fibre cable in both directions for a total distance of 192 km and attenuation of 48 dB. The observed two-photon Bell state exhibited a fidelity 85 ± 2% and was stable over several hours. We employed neither active stabilisation of the quantum state nor chromatic dispersion compensation for the fibre.

scholarly journals Experimental feasibility of molecular two-photon absorption with isolated time-frequency-entangled photon pairs

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Tiemo Landes ◽  
Markus Allgaier ◽  
Sofiane Merkouche ◽  
Brian J. Smith ◽  
Andrew H. Marcus ◽  
...  
Keyword(s):  
Photon Absorption ◽  
Time Frequency ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Photon Pairs ◽  
Entangled Photon Pairs

A Quantum Repeater Based on Entanglement Purification and Entanglement Swapping

2013 ◽  
Vol 302 ◽  
pp. 607-611
Author(s):  
Zhen Zhu Zhou ◽  
Wei He ◽  
Chun Dan Zhu ◽  
Ying Wang
Keyword(s):  
Quantum Communication ◽  
Entanglement Swapping ◽  
High Fidelity ◽  
Quantum Repeater ◽  
Long Distance ◽  
Entanglement Purification ◽  
Photon Pairs ◽  
The Common ◽  
Entangled Photon Pairs ◽  
Epr Pair

We discuss a long-distance quantum communication system based on entangled photon pairs, which apply entanglement as its fundamental resource. For distances longer than the coherence length of a counterpart noisy quantum channel, the fidelity of transmission is ordinarily so low that standard purification processes are not applicable. The quantum repeater stretches the length of the entangled photon pairs. And the high fidelity entanglement of photons between sender and receiver is obtained by entanglement purification and entanglement swapping. We compare the nested repeater with the common repeater and show that it outperforms the latter, which is built an EPR pair in less time.

scholarly journals Integrated Source of Path-Entangled Photon Pairs with Efficient Pump Self-Rejection

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1952
Author(s):  
Pablo de la Hoz ◽  
Anton Sakovich ◽  
Alexander Mikhalychev ◽  
Matthew Thornton ◽  
Natalia Korolkova ◽  
...  
Keyword(s):  
Collective Mode ◽  
Narrow Band ◽  
Fused Silica ◽  
Two Photon ◽  
Photon Pairs ◽  
Entangled Photon Pairs ◽  
Set Up ◽  
Fused Silica Glass ◽  
Kerr Nonlinear Media ◽  
Theoretical Proposal

We present a theoretical proposal for an integrated four-wave mixing source of narrow-band path-entangled photon pairs with efficient spatial pump self-rejection. The scheme is based on correlated loss in a system of waveguides in Kerr nonlinear media. We calculate that this setup gives the possibility for upwards of 100 dB pump rejection, without additional filtering. The effect is reached by driving the symmetric collective mode that is strongly attenuated by an engineered dissipation, while photon pairs are born in the antisymmetric mode. A similar set-up can additionally be realized for the generation of two-photon NOON states, also with pump self-rejection. We discuss the implementation of the scheme by means of the coherent diffusive photonics, and demostrate its feasibility in both glass (such as fused silica-glass and IG2) and planar semiconductor waveguide structures in indium phosphide (InP) and in silicon.

scholarly journals Twin-Field Quantum Key Distribution over 511 km Optical Fiber Linking two Distant Metropolitans

2021 ◽  
Author(s):  
Jiu-Peng Chen ◽  
Chi Zhang ◽  
Yang Liu ◽  
Cong Jiang ◽  
Weijun Zhang ◽  
...  
Keyword(s):  
Quantum State ◽  
Quantum Key Distribution ◽  
Large Scale ◽  
Single Photon ◽  
Key Distribution ◽  
Test System ◽  
Long Distance ◽  
Quantum Networks ◽  
The Cost ◽  
Remarkable Progress

Abstract The basic principle of quantum mechanics guarantee the unconditional security of quantum key distribution (QKD) at the cost of inability of amplification of quantum state. As a result, despite remarkable progress in worldwide metropolitan QKD networks over the past decades, long haul fiber QKD network without trustful relay has not been achieved yet. Here, through sending-or-not-sending (SNS) protocol, we complete a twin field QKD (TF-QKD) and distribute secure keys without any trusted repeater over a 511 km long haul fiber trunk linking two distant metropolitans. Our secure key rate is around 3 orders of magnitudes greater than what is expected if the previous QKD field test system over the same length were applied. The efficient quantum-state transmission and stable single-photon interference over such a long distance deployed fiber paves the way to large-scale fiber quantum networks.

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