Berlin 2018 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 9: Quantum Dots, Quantum Wires, Point Contacts
TT 9.5: Talk
Monday, March 12, 2018, 10:45–11:00, HFT-FT 101
Charge-vibration interaction in normal-superconductor quantum dots — •Gianluca Rastelli1, Pascal Stadler2, and Wolfgang Belzig2 — 1Zukunftskolleg & Fachbereich Physik, Universität Konstanz, Konstanz, Germany — 2Fachbereich Physik, Universität Konstanz, Konstanz, Germany
We study the quantum transport and the nonequilibrium vibrational states of a quantum dot embedded between a normal-conducting and a superconducting lead with the charge on the quantum dot linearly coupled to a harmonic oscillator of frequency ω [1,2]. We analyze the inelastic, vibration-assisted tunneling processes in the regime ω < Δ , with the superconducting energy gap Δ , and for sharp resonant transmission through the dot. Inelastic vibration-assisted Andreev reflections as well as quasiparticle tunneling induce a strong nonequilibrium state of the oscillator. In particular, we show that ground-state cooling of the oscillator - with phonon occupation n << 1 - can be achieved simultaneously for many of the oscillator’s modes of different frequencies. We discuss how the nonequilibrium vibrational state can be readily detected by the asymmetric behavior of the inelastic current peaks with respect to the gate voltage.
Phys. Rev. B. 96 , 045429 (2017);
Phys. Rev. Lett. 117, 197202 (2016).