BEGIN:VCALENDAR VERSION:2.0 CALSCALE:GREGORIAN PRODID:UW-Madison-Physics-Events BEGIN:VEVENT SEQUENCE:0 UID:UW-Physics-Event-2675 DTSTART:20121011T150000Z DURATION:PT1H0M0S DTSTAMP:20260416T215136Z LAST-MODIFIED:20121008T125144Z LOCATION:5310 Chamberlin SUMMARY:The Kondo exciton: a quantum quench towards strong spin-reserv oir correlations\, R. G. Herb Condensed Matter Seminar\, Hakan Tureci\ , Princeton University DESCRIPTION:When a quantum system is subjected to a quantum quench\, i ts subsequent dynamics is governed by energy scales that become ever l ower with increasing time: whereas the transient behavior right after the quench depends on high-energy excitations\, the asymptotic long-ti me evolution is determined by low-lying excitations close to the final ground state. Thus\, time- or frequency-resolved probes of the dynami cs after a quantum quench offers insight into the nature of the system 's eigenstates across the entire energy spectrum. We recently proposed [1] that such a quantum quench for the single-impurity Anderson Mode l can be induced by the sudden creation of an exciton in a quantum dot via optical absorption of an incident photon of definite frequency. T he subsequent emergence of correlations between the spin degrees of fr eedom of the dot and a tunnel-coupled low-temperature Fermionic reserv oir\, ultimately leading to the Kondo effect\, can be accurately mappe d out through an optical absorption experiment. This experiment was re cently carried out [2] with semiconductor quantum dots coupled to a de generate electron gas\, demonstrating experimentally for the first tim e the optical signature of Kondo correlations. I will discuss the theo ry behind the resulting lineshape that is found to unveil three very d ifferent dynamical regimes\, corresponding to short\, intermediate and long times after the initial excitation\, which are in turn described by the three renormalization group fixed points of the Anderson Model . At low temperatures and just beyond the absorption threshold\, the l ineshape is dominated by a power-law singularity\, with an exponent th at is a universal function of magnetic field and gate voltage.
\n< br> \n[1] H. E. Tureci et al.\, Phys. Rev. Lett. 106\, 107402 (2011).< br> \n[2] C. Latta et al.\, Nature 474\, 627 (2011). URL:https://www.physics.wisc.edu/events/?id=2675 END:VEVENT END:VCALENDAR