# Controlling the dynamics of a coupled atom-cavity system by pure dephasing: basics and potential applications in nanophotonics 

A. Auff`eves $^{1}$, ∗ D. Gerace $^{2}$, J.-M. G´ erard $^{3}$, M. 

Fran¸ca Santos $^{4}$, L. C. Andreani$^{2}$, and J.-P. Poizat1 

1 CEA/CNRS/UJF Joint team “Nanophysics and semiconductors,” Institut N´ eel-CNRS, BP 166, 25, rue des Martyrs, 38042 Grenoble Cedex 9, France 

2 Dipartimento di Fisica “Alessandro Volta,” and UdR CNISM, Universit` a di Pavia, via Bassi 6, 27100 Pavia, Italy 

3 CEA/CNRS/UJF Joint team “Nanophysics and semiconductors,” CEA/INAC/SP2M, 17 rue des Martyrs, 38054 Grenoble, France and 

4 Departamento de F´ısica, Universidade Federal de Minas Gerais, Caixa Postal 702, 30123-970, Belo Horizonte, Brazil 

(Dated: October 29, 2018) 

## Abstract 

The influence of pure dephasing on the dynamics of the coupling between a two-level atom and a cavity mode is systematically addressed. We have derived an effective atom-cavity coupling rate that is shown to be a key parameter in the physics of the problem, allowing to generalize the known expression for the Purcell factor to the case of broad emitters, and to define strategies to optimize the performances of broad emitters-based single photon sources. Moreover, pure dephasing is shown to be able to restore lasing in presence of detuning, a further demonstration that decoherence can be seen as a fundamental resource in solid-state cavity quantum electrodynamics, offering appealing perspectives in the context of advanced nano-photonic devices. We propose experimental strategies to develop a new type of versatile device that can be operated either as a single photon source or as a laser, based on the control by decoherence of the coupling between a single quantum dot and a solid-state cavity. 

PACS numbers: 42.50.Pq, 42.50.Ct, 42.50.Gy, 42.65.Hw 

