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arXiv · 2407.00758

Quantum noise induced nonreciprocity for single photon transport in parity-time symmetric systems

Dibyendu Roy·G. S. Agarwal
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Abstract

We show nonreciprocal light propagation for single-photon inputs due to quantum noise in coupled optical systems with gain and loss. We consider two parity-time ($\mathcal{PT}$) symmetric linear optical systems consisting of either two directly coupled resonators or two finite-length waveguides evanescently coupled in parallel. One resonator or waveguide is filled with an active gain medium and the other with a passive loss medium. The light propagation is reciprocal in such $\mathcal{PT}$ symmetric linear systems without quantum noise. We show here that light transmission becomes nonreciprocal when we include quantum noises in our modeling, which is essential for a proper physical description. The quantum nonreciprocity is especially pronounced in the $\mathcal{PT}$ broken phase. Transmitted light intensity in the waveguide of incidence is asymmetric for two waveguides even without noise. Quantum noise significantly enhances such asymmetry in the broken phase.

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Dibyendu Roy, G. S. Agarwal. 2024-06-30. Quantum noise induced nonreciprocity for single photon transport in parity-time symmetric systems. https://doi.org/10.1103/physreva.111.013702

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