A Radio Frequency Charge Parity Meter

TL;DR

This paper demonstrates a radio frequency technique to measure charge parity in a quantum dot system, revealing magnetic field effects and enabling precise characterization of quantum dot parameters.

Contribution

It introduces a novel RF charge parity measurement method using a resonator coupled to a nanowire quantum dot, providing insights into charge states and spin transitions.

Findings

High sensitivity detection of charge parity via RF signals

Observation of magnetic field dependence in even parity transitions

Accurate measurement of tunnel coupling and coupling rate g_c/2pi ~ 17 MHz

Abstract

We demonstrate a total charge parity measurement by detecting the radio frequency signal that is reflected by a lumped element resonator coupled to a single InAs nanowire double quantum dot. The high frequency response of the circuit is used to probe the effects of the Pauli exclusion principle at interdot charge transitions. Even parity charge transitions show a striking magnetic field dependence that is due to a singlet-triplet transition, while odd parity transitions are relatively insensitive to magnetic field. The measured response agrees well with cavity input-output theory, allowing accurate measurements of the interdot tunnel coupling and the resonator-charge coupling rate g_c/2pi ~ 17 MHz.