Impedance measurement technique for quantum systems

TL;DR

This paper revisits the impedance measurement technique for quantum systems, demonstrating how classical tank circuits can probe the phase-dependent inductance of superconducting qubits to infer their quantum states based on energy level populations.

Contribution

It introduces a theoretical framework for using impedance measurement to determine quantum states in superconducting qubits, expanding the classical technique to quantum systems.

Findings

Measurement outcome depends on qubit energy level populations.

The technique allows non-invasive quantum state measurement.

Theoretical analysis supports potential experimental implementation.

Abstract

The impedance measurement technique consists in that the phase-dependent (parametric) inductance of the system is probed by the classical tank circuit via measuring the voltage. The notion of the parametric inductance for the impedance measurement technique is revisited for the case when a quantum system is probed. Measurement of the quantum state of the system of superconducting circuits (qubits) is studied theoretically. It is shown that the result of the measurement is defined by the partial energy levels populations in the qubits.