Fast microwave beam splitters from superconducting resonators

TL;DR

This paper demonstrates the design and experimental realization of superconducting microstrip resonators that function as fast, high-purity microwave beam splitters with tunable coupling strengths, advancing quantum information processing capabilities.

Contribution

It introduces a method to tune the two-mode squeezer coupling in superconducting resonators, enabling fast and pure beam splitters with high coupling rates.

Findings

Tunable two-mode squeezer coupling from 2.4% to 12.9% of resonance frequency.

Achieved a beam splitter coupling rate of 810 MHz.

Demonstrated suppression of two-mode squeezing for pure beam splitting.

Abstract

Coupled superconducting transmission line resonators have applications in quantum information processing and fundamental quantum mechanics. A particular example is the realization of fast beam splitters, which however is hampered by two-mode squeezer terms. Here, we experimentally study superconducting microstrip resonators which are coupled over one third of their length. By varying the position of this coupling region we can tune the strength of the two-mode squeezer coupling from 2.4% to 12.9% of the resonance frequency of 5.44GHz. Nevertheless, the beam splitter coupling rate for maximally suppressed two-mode squeezing is 810MHz, enabling the construction of a fast and pure beam splitter.