Survival-Probability of a local excitation in a Non-Markovian environment: Survival Collapse, Zeno and Anti-Zeno effects

E. RUFEIL FIORI; H. M. PASTAWSKI

Buenos Aires

Congreso; At the frontiers of condensed matter IV; 2008

Gerencia de Investigaciones y Aplicaciones, Comisión Nacional de Energía Atómica y Departamento de Física, Facultad de Ciencias Exactas y Naturales Universidad de Buenos Aires

Nanosystems are never isolated, but they interact with the macroscopic world. In consequence the excitations have a survival probability Poo which typically decay according to the Fermi Golden Rule. However, this approximation neglects memory effects in the environment, which could be relevant. In this work we address effects that an electrode, considered as environment, has on the excitations of a quantum dot. To simplify the treatment we consider a single state of the dot which is weakly coupled to an environment whose dynamics can be solved within a Hamiltonian model. Various works showed that the exponential decay has superimposed beats and does not hold for very short and very long times, compared with the lifetime of the system. We presented a model describing the evolution of a surface excitation in a semi-infinite spin chain, a model that is solved analytically and susceptible for an experimental test. Here, we present a general analysis showing the quantum nature of the deviations from the Fermi Golden Rule. We identify three time regimes in the decay of the survival probability Poo.