SFB 767 - TP C03 "Time-dependent transport in correlated in electron nanostructures"
The goal of the project was to develop new theoretical methods for time-dependent transport through nanoscale junctions. We have first shown that the measurement of the quantum electric noise of the current is an intrinsic quantum mechanical measurement problem, which requires to take into account the measurement apparatus and implies that an ideal detector has to add a certain amount of noise to avoid the problem of backaction. Next we have investigated the effect of a time-dependent bias voltage on the statistics of the charge transfer and were able to show that in general at finite temperature it is impossible to separate the statistics into only single- and two-particle events. Finally we have considered the correction to the current noise of a molecular contact due to electron-phonon interaction. We have predicted that the noise for a junction consisting of a deuterium molecule between metallic contacts increases significantly.p
- AG Belzig (Theoretische Physik mit SP Quantentransport)
|(2016): Ground-State Cooling of a Mechanical Oscillator by Interference in Andreev Reflection Physical Review Letters. 2016, 117, 197202. ISSN 0031-9007. eISSN 1079-7114. Available under: doi: 10.1103/PhysRevLett.117.197202
We study the ground-state cooling of a mechanical oscillator linearly coupled to the charge of a quantum dot inserted between a normal metal and a superconducting contact. Such a system can be realized, e.g., by a suspended carbon nanotube quantum dot with a capacitive coupling to a gate contact. Focusing on the subgap transport regime, we analyze the inelastic Andreev reflections which drive the resonator to a nonequilibrium state. For small coupling, we obtain that vibration-assisted reflections can occur through two distinct interference paths. The interference determines the ratio between the rates of absorption and emission of vibrational energy quanta. We show that ground-state cooling of the mechanical oscillator can be achieved for many of the oscillator's modes simultaneously or for single modes selectively, depending on the experimentally tunable coupling to the superconductor.
|01.01.2008 – 31.12.2019