Dynamical Lamb effect in a tunable superconducting qubitcavity system
Abstract
A natural atom placed into a cavity with timedependent parameters can be parametrically excited due to interaction with the quantized photon mode. One of the channels for this process is the dynamical Lamb effect, induced by a nonadiabatic modulation of the atomiclevel 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 (an artificial macroscopic atom) provides a unique platform for observation of the dynamical Lamb effect. A key idea is to exploit a dynamically tunable qubitresonator coupling, which was implemented quite recently. By varying the coupling nonadiabatically, it is possible to parametrically excite a qubit through a nonadiabatic modulation of the Lamb shift, even if the cavity was initially empty. The dynamics of such a coupled system is studied within the Rabi model with a timedependent coupling constant and beyond the rotatingwave approximation. An efficient method to increase the effect through the periodic and nonadiabatic switching of the qubitresonator coupling energy is proposed.
 Publication:

Physical Review A
 Pub Date:
 June 2015
 DOI:
 10.1103/PhysRevA.91.063814
 arXiv:
 arXiv:1503.01666
 Bibcode:
 2015PhRvA..91f3814S
 Keywords:

 42.50.Ct;
 42.50.Dv;
 85.25.Am;
 Quantum description of interaction of light and matter;
 related experiments;
 Nonclassical states of the electromagnetic field including entangled photon states;
 quantum state engineering and measurements;
 Superconducting device characterization design and modeling;
 Condensed Matter  Mesoscale and Nanoscale Physics;
 Condensed Matter  Superconductivity;
 Physics  Atomic Physics;
 Quantum Physics
 EPrint:
 16 pages, 8 figures