Detecting Optical Channel Non-Reciprocity with Non-Local Quantum Geometric Phase
Non-reciprocal devices are of increasing interest in quantum information technologies. This paper examines whether the presence of a non-reciprocal device in an optical channel is detectable by the communicating parties. We find that a non-reciprocal device such as a Faraday Rotator results in a measurable geometric phase for the light propagating through the channel and that, when using entangled photon pairs, the resulting phase is non-local and robust against malicious manipulation.
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