# Mach-Zehnder interferometer with quantum beamsplitters

## TL;DR

This paper proposes a fully quantum Mach-Zehnder interferometer using quantum beamsplitters in a waveguide, analyzing its nonlinearities and demonstrating its equivalence to classical models in certain regimes.

## Contribution

It introduces a novel fully quantum interferometer design with analytical insights into its nonlinear behavior and equivalence to classical transfer-matrix methods.

## Key findings

- Nonlinear effects due to photon-emitter detunings analyzed
- Analytical expressions for photodetection probabilities derived
- Equivalence with classical transfer-matrix approach proven in monochromatic regime

## Abstract

A one-dimensional waveguide enables a single two-level emitter to route the propagation of a single photon, as to provide a quantum mirror or a quantum beamsplitter. Here we present a fully-quantum Mach-Zehnder interferometer (QMZ) for single-photon pulses comprised of two quantum beamsplitters. We theoretically show how nonlinearities of the QMZ due to photon-emitter detunings and to the spectral linewidth of the pulse contribute to the versatility of the device with respect to the classical-beamsplitters scenario. We employ a quantum dynamics framework to obtain analytical expressions for the photodetection probabilities and prove, in the monochromatic regime, the equivalence with a transfer-matrix approach.