ELFT HÍRADÓ

[Varga Imre <varga AT galilei.phy.bme.hu>]

                                                  MEGHIVO
                            a BME Fizikai Intezet, Elmeleti Fizika Tanszek
                                              szeminariumara:


                                              Baruch Horovitz
                                           Physics Department
                                     Ben-Gurion University, Israel


                "Inteference, renormalization and dephasing of a particle
                                     in dissipative environments"


        Abstract:
        A charged particle on a ring of radius R is coupled to noisy 
environmnets
        such as a Caldeira Legget (CL) type or a dirty metal. The 
Aharonov-Bohm
        oscillation amplitude represents either mass renormalization or 
dephasing.
        In the CL case this amplitude is ~exp(-R^2) indicating dephasing at
        temperature T=0, while for a dirty metal the amplitude is ~1/R^2, 
indicating
        a renormalized mass M*. Monte Carlo data indicates a phase transition 
in M*:
        For large rings M* scales with TR and approaches an R independent M* 
at T=0.
        For small rings M* scales with TR^4 approaching an R dependent M* at 
T=0. A
        perturbative formula for dephasing is derived, showing at T=0 power 
law
        decay of coherence in the CL case, while no dephasing for a dirty 
metal. At
        finite T dephasing lengths are indentified, in agreement with the 
Monte
        Carlo data.


        Helye: BME Fizikai Intezet,
                  Elmeleti Fizika Tanszek
                  Budafoki ut 8.
                  F-epulet, III. lepcsohaz, mfszt. Szeminariumi szoba

        Ideje: 2007. szeptember 7. pentek, 10:15.


        Minden erdeklodot szivesen latunk.


                                                                              
          Varga Imre