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.

中文翻译：

---

参数驱动超导谐振器中的周期倍增

我们报告了参数驱动可调谐超导谐振器中周期倍增的实验观察。我们通过连接到四分之一波长谐振器的超导量子干涉装置调制磁通量，频率 $n\omega$ 接近倍数，$n=2,\,3,\,4,\,5$,谐振器基模并观察 $\omega$ 处的强烈输出辐射。输出字段表现出 $n$-fold 相对于相位的简并性，$n$ 状态相对于彼此相移 $2\pi/n$。我们的演示验证了郭等人的理论预测。在 PRL 111, 205303 (2013) 中，并为使用微波光子设计复杂的宏观量子猫态铺平了道路。