Cooling a mechanical resonator by quantum interference in a triple quantum dot

TL;DR

This paper introduces a method to cool a mechanical resonator using quantum interference effects in a triple quantum dot system, enabling ground state cooling through electron tunneling and quantum superposition.

Contribution

It presents a novel cooling scheme leveraging quantum interference in a triple quantum dot, with a proposed measurement method for verifying the cooling effect.

Findings

Cooling of the mechanical resonator to its ground state is achievable.

Quantum interference creates a dark state that facilitates energy absorption from the resonator.

A charge detection scheme can verify the cooling process.

Abstract

We propose an approach to cool a mechanical resonator (MR) via quantum interference in a triple quantum dot (TQD) capacitively coupled to the MR. The TQD connected to three electrodes is an electronic analog of a three-level atom in $\Lambda$ configuration. The electrons can tunnel from the left electrode into one of the two dots with lower-energy states, but can only tunnel out from the higher-energy state at the third dot to the right electrode. When the two lower-energy states are tuned to be degenerate, an electron in the TQD can be trapped in a superposition of the degenerate states called the dark state. This effect is caused by the destructive quantum interference between tunneling from the two lower-energy states to the higher-energy state. Under this condition, an electron in the dark state readily absorbs an energy quantum from the MR. Repeating this process, the MR can be cooled to its ground state. Moreover, we propose a scheme for verifying the cooling result by measuring the current spectrum of a charge detector adjacent to a double quantum dot coupled to the MR.