Dynamical Autler-Townes control of a phase qubit

TL;DR

This paper demonstrates how a superconducting phase qubit can be dynamically controlled as an optical switch using Autler-Townes splitting, enabling fast ON/OFF photon transmission control in quantum information systems.

Contribution

It introduces a method to control a superconducting qubit as a fast optical switch via Autler-Townes splitting, supported by a three-level model matching experimental data.

Findings

Achieved 100 ns switching time for photon reflection/transmission.

Demonstrated control of photon absorption and transmission using Autler-Townes effect.

Validated a three-level model with relaxation and dephasing parameters.

Abstract

Routers, switches, and repeaters are essential components of modern information-processing systems. Similar devices will be needed in future superconducting quantum computers. In this work we investigate experimentally the time evolution of Autler-Townes splitting in a superconducting phase qubit under the application of a control tone resonantly coupled to the second transition. A three-level model that includes independently determined parameters for relaxation and dephasing gives excellent agreement with the experiment. The results demonstrate that the qubit can be used as a ON/OFF switch with 100 ns operating time-scale for the reflection/transmission of photons coming from an applied probe microwave tone. The ON state is realized when the control tone is sufficiently strong to generate an Autler-Townes doublet, suppressing the absorption of the probe tone photons and resulting in a maximum of transmission.