Spectroscopy on two coupled flux qubits

TL;DR

This paper reports on spectroscopy measurements of two inductively coupled flux qubits, revealing their interaction through resonance shifts and confirming the coupling strength aligns with theoretical calculations.

Contribution

The study demonstrates direct spectroscopic observation of coupled flux qubits and quantifies their interaction strength, validating theoretical models.

Findings

Resonances observed correspond to transitions from ground to excited states.

Coupling strength matches mutual inductance calculations.

Magnetic field dependence confirms qubit coupling.

Abstract

We have performed spectroscopy measurements on two coupled flux qubits. The qubits are coupled inductively, which results in a $\sigma_1^z\sigma_2^z$ interaction. By applying microwave radiation, we observe resonances due to transitions from the ground state to the first two excited states. From the position of these resonances as a function of the magnetic field applied we observe the coupling of the qubits. The coupling strength agrees well with calculations of the mutual inductance.