Fig. 1: Tunable, non-Hermitian, nonlinear microwave dimer.
From: Demonstration of a tunable non-Hermitian nonlinear microwave dimer
a Depiction of individual cavities with a mechanically-adjustable resonance frequency and coupling rates. b An exploded view of the cavity, showing how cavities are assembled with locking pins to set experimental parameters after calibration. c Schematic of the dimer system formed from two tunable microwave harmonic oscillators with frequencies ωc/2π = 6.027(5) GHz and internal quality factors of Qint = ωc/κint ≈ 1488. The oscillators are connected with a characteristic coupling strength of κc/2π = 8.7(1) MHz. When the amplifier is in its normal operating regime, this coupling is determined by a characteristic gain, G0 = 20.3(2) dB, and subsequently adjusted through digital attenuation, Γ. On the return path (cavity 2 → cavity 1), a phase shifter introduces a relative phase, ϕ, between the two coupling paths. We couple photons into and out of the cavity at an average rate κin,out/2π = 4.0(2) MHz.
