近日，美国密歇根大学的Theodore Goodson III及其研究小组与美国西北大学的Charles J. Zeman IV等人合作，研究了纠缠双光子吸收的颜色
本文对分子系统中纠缠双光子吸收（ETPA）过程的激发波长依赖性进行了理论和实验研究，为纠缠如何影响分子光谱提供了见解。研究人员发现，ETPA的激发谱可以不同于经典的TPA和双频光子的单光子共振吸收（OPA）的激发谱。这些结果是通过假设ETPA截面由双光子激发态辐射线宽而不是电子-声子相互作用控制来建模的，这导致了与观察结果相匹配的激发光谱。此外，他们发现具有最高TPA和ETPA强度的双光子允许状态具有高电子纠缠，其中ETPA尤其有利于具有最长辐射寿命的状态。
这些结果为基于量子光的光谱学和显微镜学的发展提供了概念，将导致更高效率的ETPA传感器和低强度检测方案。
据悉，纠缠光子的多光子吸收为获取化学和生物过程的独特信息提供了途径。使用纠缠光子的测量可以在非常低的光水平下以高选择性感知生物特征，以防止光损伤。
附：英文原文
Title: Colors of entangled two-photon absorption
Author: Varnavski, Oleg, Giri, Sajal Kumar, Chiang, Tse-Min, Zeman, Charles J., Schatz, George C., Goodson III, Theodore
Issue&Volume: 2023-8-21
Abstract: Multiphoton absorption of entangled photons offers ways for obtaining unique information about chemical and biological processes. Measurements with entangled photons may enable sensing biological signatures with high selectivity and at very low light levels to protect against photodamage. In this paper, we present a theoretical and experimental study of the excitation wavelength dependence of the entangled two-photon absorption (ETPA) process in a molecular system, which provides insights into how entanglement affects molecular spectra. We demonstrate that the ETPA excitation spectrum can be different from that of classical TPA as well as that for one-photon resonant absorption (OPA) with photons of doubled frequency. These results are modeled by assuming the ETPA cross-section is governed by a two-photon excited state radiative linewidth rather than by electron-phonon interactions, and this leads to excitation spectra that match the observed results. Further, we find that the two-photon-allowed states with highest TPA and ETPA intensities have high electronic entanglements, with ETPA especially favoring states with the longest radiative lifetimes. These results provide concepts for the development of quantum light–based spectroscopy and microscopy that will lead to much higher efficiency of ETPA sensors and low-intensity detection schemes.
DOI: 10.1073/pnas.2307719120
Source: https://www.pnas.org/doi/10.1073/pnas.2307719120