Non-Markovian Unified Theory of Dephasing in Two-Photon and Multiphoton Processes

Per Kaer, Toke Rammer Nielsen, Peter Lodahl +2 more

Ahsan Nazir, S. D. Barrett

K.‐E. Süsse, W. Vogel, D.‐G. Welsch

Farhad H. M. Faisal

Zhifang Deng

The authors study an autoionisation model undergoing a collisional dephasing process. The photoelectron spectrum is defined in terms of the tetradic scattering formulation. The theory uses projection operator techniques in Liouville space to perform selective averagings over the bath variables. In the weak-field case, the long-time photoelectron spectrum is derived and calculated, and it is expressed by the single-photon lineshape functions. The authors' result enables one to analyse the Markovian and non-Markovian lineshapes. They show the different aspects of the spectrum in these two cases.

Antoine Reigue, Jake Iles-Smith, Fabian R. Lux +9 more

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.