Noise-induced spectral shift measured in a Double Quantum Dot

TL;DR

This study measures shot noise in a quantum point contact using a double quantum dot sensor, revealing how noise induces spectral shifts in electron tunneling rates due to inelastic processes.

Contribution

The paper provides the first direct measurement of noise-induced spectral shifts in a double quantum dot using time-resolved charge sensing.

Findings

Inelastic tunneling rates increase with quantum point contact noise.

Spectral weight conservation is confirmed experimentally.

Detuning controls the detector frequency and tunneling dynamics.

Abstract

We measure the shot noise of a quantum point-contact using a capacitively coupled InAs double quantum dot as an on-chip sensor. Our measurement signals are the (bidirectional) interdot electronic tunneling rates which are determined by means of time-resolved charge sensing. The detector frequency is set by the relative detuning of the energy levels in the two dots. For nonzero detuning, the noise in the quantum point contact generates inelastic tunneling in the double dot and thus causes an increase in the interdot tunneling rate. Conservation of spectral weight in the dots implies that this increase must be compensated by a decrease in the rate close to zero detuning, which is quantitatively confirmed in our experiment.