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DOE OSTI · 3000274

Symmetry Protected Two-Photon Coherence Time

Lai, Xuanying·Li, Christopher·Zanders, Alan·Mei, Yefeng·Du, Shengwang
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Abstract

We report the observation of symmetry protected two-photon coherence time of biphotons generated from backward spontaneous four-wave mixing in laser-cooled 87 Rb atoms. When biphotons are nondegenerate, nonsymmetric photonic absorption loss results in exponential decay of the temporal waveform of the two-photon joint probability amplitude, leading to shortened coherence time. In contrast, in the case of degenerate biphotons, when both paired photons propagate with the same group velocity and absorption coefficient, the two-photon coherence time, protected by space-time symmetry, remains unaffected by medium absorptive losses. Furthermore, our experimental results validate these theoretical predictions. This outcome highlights the pivotal role of symmetry in manipulating and controlling photonic quantum states.

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74 ATOMIC AND MOLECULAR PHYSICSCoherence timeElectromagnetically induced transparencyNonlinear opticsPhoton pairs & parametric down-conversionPhysicsQuantum coherence & coherence measuresQuantum correlations, foundations & formalismQuantum opticsQuantum states of lightSymmetryTwo-photon state

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Lai, Xuanying, Li, Christopher, Zanders, Alan, Mei, Yefeng, Du, Shengwang. 2024-07-16. Symmetry Protected Two-Photon Coherence Time. https://doi.org/10.1103/physrevlett.133.033601

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