Superconducting switch for fast on-chip routing of quantum microwave fields

TL;DR

This paper presents a superconducting on-chip microwave switch capable of fast, low-loss routing of quantum signals at cryogenic temperatures, suitable for quantum information processing and other quantum technologies.

Contribution

The authors design and experimentally demonstrate a superconducting microwave switch integrated on-chip, operating at cryogenic temperatures with high bandwidth and minimal heat dissipation, compatible with quantum applications.

Findings

Operates with >100 MHz bandwidth

Handles photon fluxes >10^5 μs^{-1}

Switching time of 6-8 ns

Abstract

A switch capable of routing microwave signals at cryogenic temperatures is a desirable component for state-of-the-art experiments in many fields of applied physics, including but not limited to quantum information processing, communication and basic research in engineered quantum systems. Conventional mechanical switches provide low insertion loss but disturb operation of dilution cryostats and the associated experiments by heat dissipation. Switches based on semiconductors or microelectromechanical systems have a lower thermal budget but are not readily integrated with current superconducting circuits. Here we design and test an on-chip switch built by combining tunable transmission-line resonators with microwave beam-splitters. The device is superconducting and as such dissipates a negligible amount of heat. It is compatible with current superconducting circuit fabrication techniques, operates with a bandwidth exceeding $100\,\mathrm{MHz}$, is capable of handling photon fluxes on the order of $10^{5}\,\mu\mathrm{s}^{-1}$, equivalent to powers exceeding $-90\,\mathrm{dBm}$, and can be switched within approximately $6-8\,\mathrm{ns}$. We successfully demonstrate operation of the device in the quantum regime by integrating it on a chip with a single-photon source and using it to route non-classical itinerant microwave fields at the single-photon level.