Generation of Superposition States and Charge-Qubit Relaxation Probing in a Circuit

TL;DR

This paper demonstrates generating superposition states of microwave fields in a circuit and uses charge-qubit relaxation to probe decoherence, revealing insights into qubit-field interactions and relaxation processes.

Contribution

It introduces a method to generate superposition states in microwave fields and links qubit relaxation dynamics to field decoherence in a superconducting circuit.

Findings

Superposition states can be generated via magnetic pulse chirping.

Qubit dephasing causes measurable decoherence in the field.

Charge-qubit relaxation influences the field state decoherence profile.

Abstract

We demonstrate how a superposition of coherent states can be generated for a microwave field inside a coplanar transmission line coupled to a single superconducting charge qubit, with the addition of a single classical magnetic pulse for chirping of the qubit transition frequency. We show how the qubit dephasing induces decoherence on the field superposition state, and how it can be probed by the qubit charge detection. The character of the charge qubit relaxation process itself is imprinted in the field state decoherence profile.