title: Ground-State Cooling of a Mechanical Oscillator by Interference in Andreev Reflection.
abstract: 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.
authors.affiliation: Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Stadler
authors.affiliation: Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Belzig
authors.affiliation: Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Rastelli