Quantifying the enhancement of two-photon absorption due to spectral-temporal entanglement

TL;DR

This paper provides a quantum-theoretic analysis of how spectral-temporal entanglement enhances two-photon absorption, establishing bounds on the quantum enhancement and outlining experimental conditions needed for observation.

Contribution

It introduces a theoretical framework for quantifying entangled two-photon absorption and derives upper bounds on quantum enhancement achievable in such systems.

Findings

Quantum entanglement can significantly enhance two-photon absorption rates.

Experimental observation of entangled TPA requires higher photon flux and molecular concentrations.

Derived bounds limit the maximum possible quantum enhancement in practical setups.

Abstract

When a low flux of time-frequency-entangled photon pairs (EPP) illuminates a two-photon transition, the rate of two-photon absorption (TPA) can be enhanced considerably by the quantum nature of photon number correlations and frequency correlations. We present a quantum-theoretic derivation of entangled TPA (ETPA) and calculate an upper bound on the amount of quantum enhancement that is possible in such systems. The derived bounds indicate that in order to observe ETPA the experiments would need to operate at a combination of significantly higher rates of EPP illumination, molecular concentrations, and conventional TPA cross sections than are achieved in typical experiments.