# Quantum dynamics of single-photon detection using functionalized quantum transport electronic channels

## TL;DR

This paper presents a theoretical model of a nanoscale single-photon detector based on quantum transport channels, revealing unique temporal signatures and demonstrating high count rate detection via non-equilibrium backaction control.

## Contribution

It introduces a fully quantum, coupled model of photon absorption, transduction, and measurement in a nanoscale system, with novel non-linear dynamics due to backaction effects.

## Key findings

- Temporal signatures of photon detection identified
- Detection can be achieved at high count rates
- Backaction control enhances signal-to-noise ratio

## Abstract

Single photon detectors have historically consisted of macroscopic-sized materials but recent experimental and theoretical progress suggests new approaches based on nanoscale and molecular electronics. Here we present a theoretical study of photodetection in a system composed of a quantum electronic transport channel functionalized by a photon absorber. Notably, the photon field, absorption process, transduction mechanism, and measurement process are all treated as part of one fully-coupled quantum system, with explicit interactions. Using non-equilibrium, time-dependent quantum transport simulations, we reveal the unique temporal signatures of the single photon detection process, and show that the system can be described using optical Bloch equations, with a new non-linearity as a consequence of time-dependent detuning caused by the backaction from the transport channel via the dynamical Stark effect. We compute the photodetector signal-to-noise ratio and demonstrate that single photon detection at high count rate is possible for realistic parameters by exploiting a novel non-equilibrium control of backaction.