Resonance expansion versus the rotating-wave approximation (8 pages)

B. Thimmel, P. Nalbach, Orestis Terzidis

Bruce J. West, Katja Lindenberg

A. B. Klimov, Isabel Sainz, S. M. Chumakov

We propose a general perturbative approach to quantum-optical models without the rotating-wave approximation. We show that a generic Hamiltonian describing interaction between two subsystems can be represented as a series of operators corresponding to different transitions between bare energy levels of the whole system. Under certain relations between frequencies of interacting subsystems one of these transitions becomes resonant. The rotating-wave approximation leads to separation of the resonant transition and to appearance of the integral of motion, which makes the problem exactly solvable in this approximation. (Different resonance conditions lead to different integrals of motion.) All of the other terms in these expansion can be considered as a perturbation. They result in dynamic Stark shifts and small corrections to the integrals of motion. All possible resonances are classified, and approximate integrals of motion are found for each resonance. Examples of field-field, field-atom, and atom-atom interactions are considered.

U. Fano

Saad S. M. Hassan, Yasser Amoun Sharaby

The interaction of a mesoscopic system of two-level Rydberg atoms with a coherently driven single cavity mode is treated outside the rotating wave approximation (RWA). This yields a system of non-autonomous Maxwell–Bloch equations that can be solved using Fourier decomposition of both field and atomic variables up to first harmonics and to O ( Q −1 ), where Q is the cavity quality factor. For the absorber and amplifier regimes, the first harmonic component of the output field (outside the RWA) exhibits closed hysteresis loops compared with hysteresis cycles for the non-oscillatory (fundamental) component within the RWA. A cooperative switching diagram (output field versus cooperative atomic parameter) outside the RWA shows overlapping branches in the resonant case and closed loops in the non-resonant case.

Yulia V. Bezvershenko, Petro I. Holod