Quantum nonlinear cavity quantum electrodynamics with coherently prepared atoms

Abstract

We propose a method to study the quantum nonlinearity and observe the multiphoton transitions in a multiatom CQED system. We show that by inducing simultaneously destructive quantum interference for the single-photon and two-photon excitations in the CQED system, it is possible to observe the direct three-photon excitation of the higherorder ladder states of the CQED system. We report an experiment with cold Rb atoms confined in an optical cavity and demonstrate such interference control of the multiphoton excitations of the CQED system. The observed nonlinear excitation of the CQED ladder states agrees with a theoretical analysis based on a fully quantized treatment of the CQED system, but disagrees with the semiclassical analysis of the CQED system. Thus it represents the first direct observation of the quantum nature of the multiatom CQED system and opens new ways to explore quantum nonlinearity and its applications in quantum optical systems in which multiple absorbers/emitters are coupled with photons in confined cavity structures.

Perfect photon absorption in the nonlinear regime of cavity quantum electrodynamics

“…shown that the quantum interference can be used to suppress the linear absorption and enhance the quantum nonlinear absorption in a CQED system [27], which enables studies of the pure nonlinear CQED phenomena free of the linear absorption effects. Thus it will be interesting to see if the perfect photon absorption can occur under the pure quantum nonlinear excitation of the CQED.…”

“…For the CQED system, one can have a cavity with >> while operating in the linear excitation regime of the CQED system with under the condition of the prefect photon absorption versus the input frequency detuning |p|/. The system parameters are chosen to be consistent with that readily achievable experimentally [27,32]. It shows that the perfect photon absorption occurs only in the frequency range of the input light fields ; correspondingly, the CQED system evolves from the linear excitation regime into the nonlinear excitation regime.…”

“…Previous studies of perfect photon absorption are in the linear absorption regime, in which either a linear absorber is considered (such as in a solid-state Fabry-Perot etalon [6][7][8][9][10][11][12]) or in CQED, only the linear excitation of the first-order polariton states [19][20][21][22][23][24][25] are considered [19] and the multiphoton excitation of the higher-order polariton states in CQED are excluded [26][27]. Naturally this raises a question on whether coherent perfect photon absorption can occur in an optical system with a nonlinear absorber.…”

“…3, and Fig. 4 are taken from reported experimental work done on a multiatom CQED system consisting of a moderate-finesse cavity and cold Rb atoms [27,32]. With the high density of cold atoms and negligible Doppler shift, a CQED system with cold atoms is well suited for experimental studies of the perfect photon absorption and its interference manipulation in the linear and nonlinear regimes of the CQED, the interplay of the perfect photon absorption with the optical bistability, and the interference control of the CQED bistability reported here.…”

Electromagnetic control and improvement of nonclassicality in a strongly coupled single-atom cavity-QED system

“…In this work we present some interesting results for the electromagnetic control of the nonclassicality of the output field in an atom cavity QED system. Different from the early works on cavity EIT system [25,43], we consider the case that the probe field directly drives the atom rather than the cavity. In addition, we tuned the frequency of the control field to be resonant with the one photon transition, which breaks the traditional EIT condition.…”