Reigue Antoine, Iles-Smith Jake, Lux Fabian, Monniello Léonard, Bernard Mathieu, Margaillan Florent, Lemaitre Aristide, Martinez Anthony, McCutcheon Dara P S, Mørk Jesper, Hostein Richard, Voliotis Valia
Sorbonne Universités, UPMC Université Paris 06, CNRS UMR 7588, Institut des NanoSciences de Paris, F-75005 Paris, France.
Department of Photonics Engineering, DTU Fotonik, Ørsteds Plads, 2800 Kongens Lyngby, Denmark.
Phys Rev Lett. 2017 Jun 9;118(23):233602. doi: 10.1103/PhysRevLett.118.233602. Epub 2017 Jun 6.
We investigate the temperature dependence of photon coherence properties through two-photon interference (TPI) measurements from a single quantum dot (QD) under resonant excitation. We show that the loss of indistinguishability is related only to the electron-phonon coupling and is not affected by spectral diffusion. Through these measurements and a complementary microscopic theory, we identify two independent separate decoherence processes, both of which are associated with phonons. Below 10 K, we find that the relaxation of the vibrational lattice is the dominant contribution to the loss of TPI visibility. This process is non-Markovian in nature and corresponds to real phonon transitions resulting in a broad phonon sideband in the QD emission spectra. Above 10 K, virtual phonon transitions to higher lying excited states in the QD become the dominant dephasing mechanism, this leads to a broadening of the zero phonon line, and a corresponding rapid decay in the visibility. The microscopic theory we develop provides analytic expressions for the dephasing rates for both virtual phonon scattering and non-Markovian lattice relaxation.
我们通过在共振激发下对单个量子点（QD）进行双光子干涉（TPI）测量，研究了光子相干特性的温度依赖性。我们表明，不可区分性的丧失仅与电子 - 声子耦合有关，不受光谱扩散影响。通过这些测量和一个互补的微观理论，我们确定了两个独立的退相干过程，这两个过程均与声子相关。在10 K以下，我们发现振动晶格的弛豫是TPI可见度损失的主要贡献。这个过程本质上是非马尔可夫的，对应于真实的声子跃迁，导致量子点发射光谱中出现宽的声子边带。在10 K以上，量子点中向更高激发态的虚拟声子跃迁成为主要的去相位机制，这导致零声子线变宽，以及可见度相应地快速衰减。我们发展的微观理论为虚拟声子散射和非马尔可夫晶格弛豫的去相位速率提供了解析表达式。
