Tunneling spectroscopy using a probe qubit

TL;DR

This paper introduces a quantum tunneling spectroscopy method using a probe qubit to efficiently map the energy spectrum of quantum systems with minimal control bandwidth, demonstrated on an rf SQUID flux qubit.

Contribution

The paper presents a novel spectroscopy technique that couples a probe qubit to a system, enabling spectrum reconstruction through incoherent tunneling transitions with low bandwidth control.

Findings

Successfully demonstrated on an rf SQUID flux qubit

Allows spectrum mapping via incoherent tunneling transitions

Requires only low bandwidth control for operation

Abstract

We describe a quantum tunneling spectroscopy technique that requires only low bandwidth control. The method involves coupling a probe qubit to the system under study to create a localized probe state. The energy of the probe state is then scanned with respect to the unperturbed energy levels of the probed system. Incoherent tunneling transitions that flip the state of the probe qubit occur when the energy bias of the probe is close to an eigenenergy of the probed system. Monitoring these transitions allows the reconstruction of the probed system eigenspectrum. We demonstrate this method on an rf SQUID flux qubit.