| ABSTRACT: |
It is well-known that the contribution of the counter-rotating terms is insignificant in the calculation of the decay rate for the excited state of an atom in the long time limit. In this work we address the question: What is the effect of the counter-rotating terms on the dynamical evolution of the atom at short time, particularly on quantum Zeno and anti-Zeno effects?
We find the surprising result that the counter-rotating terms can have great impact on the short time evolution of the population of the excited level, and thus on the quantum Zeno and anti-Zeno effects. We present the analytical study for the multi-level atom coupled to the electromagnetic field in free space, obtain simultaneously the electron self-energy, Lamb shift and the short-time dynamics. For the hydrogen atom, we calculate the effective decay rate and find that, because of the counter-rotating terms, the Zeno time is longer by two orders of magnitude than that obtained with rotating-wave approximation, and there is no anti-Zeno effect. Consequently the experimental measurement of the quantum Zeno effect may be much easier than what was determined with the rotating-wave approximation results. |
