Economical multi-photon polarization entanglement purification with Bell state

2021 ◽  
Vol 20 (8) ◽  
Author(s):  
Lan Zhou ◽  
Ze-Kai Liu ◽  
Zi-Xuan Xu ◽  
Yi-Lun Cui ◽  
Hai-Jiang Ran ◽  
...  
Keyword(s):  
Bell State ◽  
Photon Polarization ◽  
Entanglement Purification

scholarly journals Photonic hybrid state entanglement swapping using cat state superpositions

2020 ◽  
Vol 476 (2243) ◽  
pp. 20200237
Author(s):  
Ryan C. Parker ◽  
Jaewoo Joo ◽  
Timothy P. Spiller
Keyword(s):  
Success Probability ◽  
Bell State ◽  
Continuous Variable ◽  
Entanglement Swapping ◽  
Entangled State ◽  
Entanglement Purification ◽  
Hybrid State ◽  
Fock State ◽  
Purification Scheme ◽  
Low Levels

We propose the use of hybrid entanglement in an entanglement swapping protocol, as means of distributing a Bell state with high fidelity to two parties. The hybrid entanglement used in this work is described as a discrete variable (Fock state) and a continuous variable (cat state super- position) entangled state. We model equal and unequal levels of photonic loss between the two propagating continuous variable modes, before detecting these states via a projective vacuum-one-photon measurement, and the other mode via balanced homodyne detection. We investigate homodyne measurement imperfections, and the associated success probability of the measurement schemes chosen in this protocol. We show that our entanglement swapping scheme is resilient to low levels of photonic losses, as well as low levels of averaged unequal losses between the two propagating modes, and show an improvement in this loss resilience over other hybrid entanglement schemes using coherent state superpositions as the propagating modes. Finally, we conclude that our protocol is suitable for potential quantum networking applications which require two nodes to share entanglement separated over a distance of 5 -- 10   km , when used with a suitable entanglement purification scheme.

scholarly journals Quantum teleportation with imperfect quantum dots

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
F. Basso Basset ◽  
F. Salusti ◽  
L. Schweickert ◽  
M. B. Rota ◽  
D. Tedeschi ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Quantum Teleportation ◽  
Bell State ◽  
Spectral Filtering ◽  
State Measurement ◽  
Communication Architectures ◽  
The One ◽  
Experimental Findings ◽  
Photon Source ◽  
Remarkable Progress

AbstractEfficient all-photonic quantum teleportation requires fast and deterministic sources of highly indistinguishable and entangled photons. Solid-state-based quantum emitters—notably semiconductor quantum dots—are a promising candidate for the role. However, despite the remarkable progress in nanofabrication, proof-of-concept demonstrations of quantum teleportation have highlighted that imperfections of the emitter still place a major roadblock in the way of applications. Here, rather than focusing on source optimization strategies, we deal with imperfections and study different teleportation protocols with the goal of identifying the one with maximal teleportation fidelity. Using a quantum dot with sub-par values of entanglement and photon indistinguishability, we show that the average teleportation fidelity can be raised from below the classical limit to 0.842(14), adopting a polarization-selective Bell state measurement and moderate spectral filtering. Our results, which are backed by a theoretical model that quantitatively explains the experimental findings, loosen the very stringent requirements set on the ideal entangled-photon source and highlight that imperfect quantum dots can still have a say in teleportation-based quantum communication architectures.

scholarly journals High-energy γ -photon polarization in nonlinear Breit-Wheeler pair production and γ polarimetry

2020 ◽  
Vol 2 (3) ◽  
Author(s):  
Feng Wan ◽  
Yu Wang ◽  
Ren-Tong Guo ◽  
Yue-Yue Chen ◽  
Rashid Shaisultanov ◽  
...  
Keyword(s):  
Pair Production ◽  
High Energy ◽  
Photon Polarization

scholarly journals Demonstrating the power of quantum computers, certification of highly entangled measurements and scalable quantum nonlocality

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Elisa Bäumer ◽  
Nicolas Gisin ◽  
Armin Tavakoli
Keyword(s):  
Quantum Computer ◽  
Outcome Measurement ◽  
Bell State ◽  
Bell Inequalities ◽  
Quantum Correlations ◽  
Entanglement Swapping ◽  
Quantum Nonlocality ◽  
Quantum Computers ◽  
Classical Models ◽  
Quantum Phenomena

AbstractIncreasingly sophisticated quantum computers motivate the exploration of their abilities in certifying genuine quantum phenomena. Here, we demonstrate the power of state-of-the-art IBM quantum computers in correlation experiments inspired by quantum networks. Our experiments feature up to 12 qubits and require the implementation of paradigmatic Bell-State Measurements for scalable entanglement-swapping. First, we demonstrate quantum correlations that defy classical models in up to nine-qubit systems while only assuming that the quantum computer operates on qubits. Harvesting these quantum advantages, we are able to certify 82 basis elements as entangled in a 512-outcome measurement. Then, we relax the qubit assumption and consider quantum nonlocality in a scenario with multiple independent entangled states arranged in a star configuration. We report quantum violations of source-independent Bell inequalities for up to ten qubits. Our results demonstrate the ability of quantum computers to outperform classical limitations and certify scalable entangled measurements.

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