Multipath Correlation Interference and Controlled-NOT Gate Simulation with a Thermal Source

TL;DR

This paper reveals a counter-intuitive second-order interference phenomenon with thermal light in optical interferometry, enabling simulation of quantum gates like CNOT and potentially advancing quantum circuit experiments and high-precision measurements.

Contribution

It introduces a novel interference effect with thermal sources and demonstrates its application in simulating quantum logic gates such as CNOT.

Findings

Second-order interference occurs despite large path delays.

Thermal sources can simulate entangled-state correlations.

Potential applications in quantum simulation and metrology.

Abstract

We theoretically demonstrate a counter-intuitive phenomenon in optical interferometry with a thermal source: the emergence of second-order interference between two pairs of correlated optical paths even if the time delay imprinted by each path in one pair with respect to each path in the other pair is much larger than the source coherence time. This fundamental effect could be useful for experimental simulations of small-scale quantum circuits and of $100\%$-visibility correlations typical of entangled states of a large number of qubits, with possible applications in high-precision metrology and imaging. As an example, we demonstrate the polarization-encoded simulation of the operation of the quantum logic gate known as controlled-NOT gate.