Dresden 2011 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 64: Quantum Wires: Transport
HL 64.3: Vortrag
Mittwoch, 16. März 2011, 17:00–17:15, POT 251
Quantum Faraday Effect and Gauge Invariance in Aharonov-Bohm loops — •Kicheon Kang — Department of Physics, Chonnam National University, Gwangju 500-757, Republic of Korea — Institute for Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany
We investigate an isolated Aharonov-Bohm (AB) loop composed of tunnel-coupled two quantum dots with a flux Φ penetrating the loop. Let us consider the following experiment of the state evolution with a flux switching: Initially, the loop is in the ground state at finite value of the flux Φi. Then, the flux is suddenly switched to another value Φf. Finally, the charge in one of the two dots (nj(t), j=1,2) is measured as a function of time.
We find that the flux Φ(t) does not uniquely determine the physics of this system, and Faraday induction should be taken into account. Indeed, the Faraday induction gives additional phase shift of the wave function. The Faraday-induced phase shift depends on the geometry of the system as well as the amount of the flux change. For identical tunnel couplings with circular symmetric flux, ni(t) shows a 2Φ0 periodicity.
In addition, we show that the Faraday-induced phase shift is directly observable with an adiabatic change of the flux, for a nonstationary initial state. Interestingly, this quantum Faraday effect can be understood in terms of a nontopological geometric phase.