Consistency of ground state and spectroscopic measurements on flux qubits

TL;DR

This paper demonstrates that ground state and spectroscopic measurements on flux qubits yield consistent Hamiltonian parameters, enabling Hamiltonian reconstruction for multiple qubits at low temperatures, which is valuable for quantum computing.

Contribution

It shows that ground state measurements can reliably reconstruct the Hamiltonian of coupled flux qubits, matching spectroscopic results, facilitating scalable quantum device characterization.

Findings

Excellent agreement between measurement methods for single and coupled qubits.

Ground state measurements can reconstruct multi-qubit Hamiltonians at low temperatures.

Method is promising for future quantum information processing device calibration.

Abstract

We compare the results of ground state and spectroscopic measurements carried out on superconducting flux qubits which are effective two-level quantum systems. For a single qubit and for two coupled qubits we show excellent agreement between the parameters of the pseudospin Hamiltonian found using both methods. We argue, that by making use of the ground state measurements the Hamiltonian of N coupled flux qubits can be reconstructed as well at temperatures smaller than the energy level separation. Such a reconstruction of a many-qubit Hamiltonian can be useful for future quantum information processing devices.