TY - JOUR

T1 - Effective Density of States for a Quantum Oscillator Coupled to a Photon Field

AU - Betz, Volker

AU - Castrigiano, Domenico P.L.

PY - 2011/2

Y1 - 2011/2

N2 - We give an explicit formula for the effective partition function of a harmonically bound particle minimally coupled to a photon field in the dipole approximation. The effective partition function is shown to be the Laplace transform of a positive Borel measure, the effective measure of states. The absolutely continuous part of the latter allows for an analytic continuation, the singularities of which give rise to resonances. We give the precise location of these singularities, and show that they are well approximated by first order poles with residues equal to the multiplicities of the corresponding eigenspaces of the uncoupled quantum oscillator. Thus we obtain a complete analytic description of the natural line spectrum of the charged oscillator.

AB - We give an explicit formula for the effective partition function of a harmonically bound particle minimally coupled to a photon field in the dipole approximation. The effective partition function is shown to be the Laplace transform of a positive Borel measure, the effective measure of states. The absolutely continuous part of the latter allows for an analytic continuation, the singularities of which give rise to resonances. We give the precise location of these singularities, and show that they are well approximated by first order poles with residues equal to the multiplicities of the corresponding eigenspaces of the uncoupled quantum oscillator. Thus we obtain a complete analytic description of the natural line spectrum of the charged oscillator.

UR - http://www.scopus.com/inward/record.url?scp=79951517759&partnerID=8YFLogxK

U2 - 10.1007/s00220-010-1167-8

DO - 10.1007/s00220-010-1167-8

M3 - Article

AN - SCOPUS:79951517759

SN - 0010-3616

VL - 301

SP - 811

EP - 839

JO - Communications in Mathematical Physics

JF - Communications in Mathematical Physics

IS - 3

ER -