Quasiparticle Lifetime in a Finite System: A Nonperturbative Approach
Abstract
The problem of electronelectron lifetime in a quantum dot is studied beyond perturbation theory by mapping onto the problem of localization in the Fock space. Localized and delocalized regimes are identified, corresponding to quasiparticle spectral peaks of zero and finite width, respectively. In the localized regime, quasiparticle states are singleparticlelike. In the delocalized regime, each eigenstate is a superposition of states with very different quasiparticle content. The transition energy is ɛ_{c}~=Δ\(g/lng\)^{1/2}, where Δ is mean level spacing, and g is the dimensionless conductance. Near ɛ_{c} there is a broad critical region not described by the golden rule.
 Publication:

Physical Review Letters
 Pub Date:
 April 1997
 DOI:
 10.1103/PhysRevLett.78.2803
 arXiv:
 arXiv:condmat/9609132
 Bibcode:
 1997PhRvL..78.2803A
 Keywords:

 Condensed Matter
 EPrint:
 13 pages, LaTeX, one figure