The quantum optical description of a double Mach-Zehnder interferometer

TL;DR

This paper models a double Mach-Zehnder interferometer using Quantum Optics, revealing counter-intuitive photon statistics and demonstrating Hong-Ou-Mandel antibunching effects even with delayed, non-overlapping photon wave packets.

Contribution

It provides a quantum optical formalism for the double MZI and uncovers novel interference effects with delayed photons, extending understanding of quantum interference phenomena.

Findings

Photon-count statistics remain unchanged for certain path differences.

The setup exhibits Hong-Ou-Mandel antibunching with delayed photons.

Interference effects occur even without wave packet overlap.

Abstract

In this paper we describe within the formalism of Quantum Optics (QO) a double Mach-Zehnder interferometer (MZI). For single photon Fock states this experimental setup is shown to exhibit a counter-intuitive behavior: for certain values of the path length difference of the first MZI, the singles photon-count statistics at the output detectors does not change, whatever the difference in path length for the second MZI. For simultaneously impinging light quanta, we show that this setup is able to show the same HOM antibunching effect previously obtained with a beam splitter. However, by adding substantial delays in each MZI, we can obtain the same effect even if the "photon wave packets" do not overlap at the second beam splitter.