Utilization of a microwave-analogue Aharonov-Bohm ring to explore loss of detailed balance in quantum systems

There are immense differences between classical and quantum physics, and consequently a deep interest in the transition regime between the two worlds. One question of interest is whether a controlled amount of quantum dephasing, combined with the breaking of time-reversal symmetry, can be used to create a preferential flow for electrons in a device with equivalent contacts. An Aharonov-Bohm interferometer coupled with a dephasing site has been proposed as a potential device to exhibit such non-reciprocal behavior [1]. In our recent work [2], we created a microwave analogue of this device and examined its transmission properties in both the frequency and time domain. We were able to demonstrate non-reciprocal transmission in the presence of “dephasing” (i.e. attenuation) and see a peak in non-reciprocal transmission in the semi-classical limit of the device, for both coherent and incoherent input wave sources over a wide frequency range. These results seem to support the hypothesis that the semi-classical device presented in [1] is a potential promising candidate for realizing a preferential flow for electrons at equilibrium.

[1] Bredol, P., et al. “Decoherence Effects Break Reciprocity in Matter Transport.” Phys. Rev. B 104, 115413 (2021).

[2] Chen, L., et al. “Loss of detailed balance in equilibrium due to partial quantum decoherence: A quantum graph analogue.” arXiv:2308.14712.