# Period multiplication in a parametrically driven superconducting resonator

## TL;DR

This paper experimentally demonstrates period multiplication in a superconducting resonator driven by parametric flux modulation, confirming theoretical predictions and enabling the creation of complex quantum states with microwave photons.

## Contribution

It provides the first experimental observation of period multiplication in a tunable superconducting resonator, validating prior theory and opening avenues for quantum state engineering.

## Key findings

- Observation of period multiplication for n=2 to 5.
- Phase degeneracy of the output states with phase shifts of 2π/n.
- Verification of theoretical predictions by Guo et al.

## Abstract

We report on the experimental observation of period multiplication in parametrically driven tunable superconducting resonators. We modulate the magnetic flux through a superconducting quantum interference device, attached to a quarter-wavelength resonator, with frequencies $n\omega$ close to multiples, $n=2,\,3,\,4,\,5$, of the resonator fundamental mode and observe intense output radiation at $\omega$. The output field manifests $n$-fold degeneracy with respect to the phase, the $n$ states are phase shifted by $2\pi/n$ with respect to each other. Our demonstration verifies the theoretical prediction by Guo et al. in PRL 111, 205303 (2013), and paves the way for engineering complex macroscopic quantum cat states with microwave photons.