Dynamical Lamb Effect in a Tunable Superconducting Qubit-Cavity System

Abstract

A natural atom placed into a cavity with time-dependent parameters can be parametrically excited due to the interaction with the quantized photon mode. One of the channels of such a process is the dynamical Lamb effect, induced by a nonadiabatic modulation of atomic level Lamb shift. However, in experiments with natural atoms it is quite difficult to isolate this effect from other mechanisms of atom excitation. We point out that a transmission line cavity coupled with a superconducting qubit (artificial macroscopic atom) provides a unique platform for the observation of the dynamical Lamb effect. A key idea is to exploit a dynamically tunable qubit-resonator coupling, which was implemented quite recently. By varying nonadiabatically the coupling, it is possible to parametrically excite a qubit through a nonadiabatic modulation of the Lamb shift, even if the cavity was initially empty. A dynamics of such a coupled system is studied within the Rabi model with time-dependent coupling constant and beyond the rotating wave approximation. An efficient method to increase the effect through the periodic and nonadiabatic switching of a qubit-resonator coupling energy is proposed.

16 pages, 8 figures

References in corpus (9)

• Beyond the Jaynes-Cummings model: circuit QED in the ultrastrong coupling regime
• Resolving photon number states in a superconducting circuit
• Approaching Unit Visibility for Control of a Superconducting Qubit with Dispersive Readout
• Quantum feedback control of a superconducting qubit: Persistent Rabi oscillations
• Dressed Collective Qubit States and the Tavis-Cummings Model in Circuit QED
• Microwave Photon Detector in Circuit QED
• Quantum metamaterials: Electromagnetic waves in a Josephson qubit line
• Multilevel superconducting circuits as two-qubit systems: Operations, state preparation, and entropic inequalities
• Dispersive Response of a Disordered Superconducting Quantum Metamaterial