Resonant excitations of single and two-qubit systems coupled to a tank circuit

TL;DR

This paper investigates how flux qubits interact with a tank circuit, affecting its impedance, and explores multiphoton resonances in single and coupled qubits, comparing theory with experimental spectroscopy and interferometry results.

Contribution

It provides a theoretical analysis of multiphoton resonances in flux qubits and their impact on impedance measurements, aligning with recent experimental findings.

Findings

Multiphoton resonances significantly influence the impedance of flux qubits.

Theoretical results agree with recent spectroscopy and interferometry experiments.

Coupled qubits exhibit distinct resonant behaviors compared to single qubits.

Abstract

The interaction of flux qubits with a low frequency tank circuit is studied. It is shown that changes in the state of the interacting qubits influence the effective impedance of the circuit, which is the essence of the so-called impedance measurement technique. The multiphoton resonant excitations in both single flux qubits and pairs of coupled flux qubits are investigated. In particular, we compare our theoretical results with recent spectroscopy measurements, Landau-Zener interferometry, and multiphoton fringes.