Detecting two photons with one molecule

TL;DR

This paper introduces a novel two-photon detector using a single molecule capable of sequential photon detection, modeled with input-output theory to distinguish it from traditional simultaneous two-photon absorption.

Contribution

It presents a new model of a two-photon detector based on a single molecule detecting photons sequentially, including a Hamiltonian description of the amplification process.

Findings

Model successfully distinguishes sequential photon detection from simultaneous absorption.

Incorporates a Hamiltonian framework for the amplification process.

Demonstrates potential for improved photon detection techniques.

Abstract

We apply input-output theory with quantum pulses [AH Kiilerich, K M\o lmer, Phys. Rev. Lett. {\bf 123}, 123604 (2019)] to a model of a new type of two-photon detector consisting of one molecule that can detect two photons arriving sequentially in time. The underlying process is distinct from the usual two-photon absorption process where two photons arriving simultaneously and with frequencies adding up to the resonance frequency are absorbed by a single molecule in one quantum jump. Our detector model includes a Hamiltonian description of the amplification process necessary to convert the microscopic change in the single molecule to a macroscopic signal.