Analysis of adiabatic transfer in cavity QED

TL;DR

This paper investigates the quantum dynamics of adiabatic transfer in cavity QED systems, analyzing nonadiabatic effects and optimizing conditions for efficient photon storage and retrieval in a three-level atom setup.

Contribution

It provides a detailed quantum mechanical analysis of nonadiabatic effects during adiabatic transfer in cavity QED, including numerical solutions with spontaneous decay.

Findings

Nonadiabatic excitations can affect transfer fidelity.

Optimal control laser parameters improve storage and retrieval.

Numerical results identify conditions minimizing nonadiabatic losses.

Abstract

A three-level atom in a $\Lambda$ configuration trapped in an optical cavity forms a basic unit in a number of proposed protocols for quantum information processing. Through control with an appropriate laser, this system allows for efficient storage of cavity photons into long-lived atomic excitations, and their retrieval with high fidelity. This process presumes an adiabatic transfer through the `dark state', a coherent superposition of the two lower levels of the $\Lambda$ system, by a slow variation of the intensity of the control laser. We study the full quantum mechanics of this transfer process with a view to examine the nonadiabatic effects, as the control laser is varied in time. The nonadiabatic effects arise due to inevitable excitations of the system to states involving the highest level of the $\Lambda$ configuration, which is radiative. We formulate the problem in terms of the instantaneous eigenstates and solve it numerically, allowing for spontaneous decays from the excited level. We present detailed results for both storage and retrieval for a suitable range of variation rates and intensity of the control laser, and examine optimum conditions for the transfer process.