Dephasing Free Photon Entanglement with a Quantum Dot

Journal article (2019)

Authors

A.W. Fognini QN/Afdelingsbureau , Kavli institute of nanoscience Delft
Ali Akbar Ahmadi University of Waterloo
M Zeeshan University of Waterloo
J.T. Fokkens Kavli institute of nanoscience Delft
S. J. Daley University of Waterloo
Dan Dalacu National Research Council Canada
Klaus D. Jöns AlbaNova University Center
V.G. Zwiller Kavli institute of nanoscience Delft, QN/Zwiller Lab , AlbaNova University Center
M. E. Reimer University of Waterloo
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Research Group
QN/Afdelingsbureau
Quantum dot Entanglement Single photons Fine-structure splitting
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Published Date

2019

Language

English

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Research Group

QN/Afdelingsbureau

Abstract

Generation of photon pairs from quantum dots with near-unity entanglement fidelity has been a long-standing scientific challenge. It is generally thought that the nuclear spins limit the entanglement fidelity through spin flip dephasing processes. However, this assumption lacks experimental support. Here, we show two-photon entanglement with negligible dephasing from an indium rich single quantum dot comprising a nuclear spin of 9/2 when excited quasi-resonantly. This finding is based on a significantly close match between our entanglement measurements and our model that assumes no dephasing and takes into account the detection system's timing jitter and dark counts. We suggest that neglecting the detection system is responsible for the degradation of the measured entanglement fidelity in the past and not the nuclear spins. Therefore, the key to unity entanglement from quantum dots comprises a resonant excitation scheme and a detection system with ultralow timing jitter and dark counts.