Tunable directional photon scattering from a pair of superconducting qubits

TL;DR

This paper demonstrates a method to achieve tunable directional microwave photon scattering using two superconducting transmon qubits with modulated transition frequencies, enabling control over photon propagation direction in quantum devices.

Contribution

It introduces a novel approach to control microwave photon directionality in superconducting circuits via frequency modulation of qubits, without external magnetic fields or nonlinear effects.

Findings

Directional scattering controlled by modulation phase

Forward or backward photon scattering achieved

Tunable scattering demonstrated with two qubits

Abstract

The ability to control the direction of scattered light in integrated devices is crucial to provide the flexibility and scalability for a wide range of on-chip applications, such as integrated photonics, quantum information processing and nonlinear optics. In the optical and microwave frequency ranges tunable directionality can be achieved by applying external magnetic fields, that modify optical selection rules, by using nonlinear effects, or interactions with vibrations. However, these approaches are less suitable to control propagation of microwave photons inside integrated superconducting quantum devices, that is highly desirable. Here, we demonstrate tunable directional scattering with just two transmon qubits coupled to a transmission line based on periodically modulated transition frequency. By changing the symmetry of the modulation, governed by the relative phase between the local modulation tones, we achieve directional forward or backward photon scattering.