Detection of quantum noise from mesoscopic devices with an SIS detector

TL;DR

This paper demonstrates a method to measure high-frequency quantum noise from mesoscopic devices using an SIS tunnel junction as an on-chip spectrum analyzer, revealing non-symmetrized noise and charge oscillation effects.

Contribution

It introduces a novel on-chip spectrum analyzer for high-frequency quantum noise detection in mesoscopic devices, including superconducting qubits.

Findings

Detected non-symmetrized high-frequency noise in a Josephson junction.

Observed a spectral peak at the charge oscillation frequency in a superconducting qubit.

Validated the use of SIS junctions as on-chip quantum noise detectors.

Abstract

Quantum mechanics can strongly influence the noise properties of mesoscopic devices. To probe this effect we have measured the current fluctuations at high-frequency (5-90G Hz) using a superconductor-insulator-superconductor tunnel junction as an on-chip spectrum analyzer. By coupling this frequency-resolved noise detector to a quantum device we can measure the high-frequency, non-symmetrized noise as demonstrated for a Josephson junction. The same scheme has been used to detect the current fluctuations arising from coherent charge oscillations in a two-level system, a superconducting charge qubit. A narrow band peak was observed in the spectral noise density at the frequency of the coherent charge oscillations.