A multimode model for projective photon-counting measurements

TL;DR

This paper introduces a comprehensive multimode model for projective photon-counting measurements, especially in photon-subtraction experiments, enabling more accurate analysis of experimental data and improved state preparation for quantum information.

Contribution

It presents a mode reduction method that simplifies the multimode problem to an effective two-mode model, explicitly incorporating spatial and frequency filtering effects.

Findings

Excellent agreement with experimental results using fewer parameters

Enhanced understanding of filtering effects on photon-counting measurements

Implications for optimizing non-Gaussian state production

Abstract

We present a general model to account for the multimode nature of the quantum electromagnetic field in projective photon-counting measurements. We focus on photon-subtraction experiments, where non-gaussian states are produced conditionally. These are useful states for continuous-variable quantum information processing. We present a general method called mode reduction that reduces the multimode model to an effective two-mode problem. We apply this method to a multimode model describing broadband parametric downconversion, thereby improving the analysis of existing experimental results. The main improvement is that spatial and frequency filters before the photon detector are taken into account explicitly. We find excellent agreement with previously published experimental results, using fewer free parameters than before, and discuss the implications of our analysis for the optimized production of states with negative Wigner functions.