• Physics 15, s115
Researchers have mixed a mechanical oscillator with a superconducting resonator to create a system that vibrates at GHz frequencies.
Nonlinear mechanical oscillators are more and more present in gadgets starting from sign processors to high-precision accelerometers. Usually, such oscillators can solely resonate at frequencies of up to some MHz; at increased frequencies, their buildings are too stiff to vibrate correctly, and so they produce linear, relatively than nonlinear, responses to stimuli. Now, Xu Han and his colleagues at Yale College have made a nonlinear oscillator that works at GHz frequencies .
The workforce’s gadget consists of a mechanical oscillator coupled to a nonlinear superconducting resonator. The mechanical half is a piezoelectric “bulk acoustic resonator” (BAR)—a 500-µm-thick slice of silicon topped with an aluminum nitride skinny movie—whereas the superconducting half is a capacitor whose two terminals are related by a high-kinetic-inductance superconducting ring. This nonlinear superconducting resonator sometimes vibrates at round 10 GHz, however its actual oscillation frequency depends upon the ring’s kinetic inductance, which varies nonlinearly with present.
The coupling between the BAR and the superconducting resonator is such that the superconducting half nonlinearly amplifies oscillations supported by the BAR. Han and colleagues additionally present that, when the superconducting resonator is pushed by a microwave tone at its resonant frequency, the BAR produces an acoustic frequency “comb”—a collection of mechanical oscillations at evenly spaced frequencies within the 10 GHz a part of the spectrum.
Frequency combs are already utilized in frequency metrology and distant sensing. However the sensitivity of gadgets working at MHz frequencies may be restricted by thermal noise. Such noise scales inversely with the resonant frequency and is thus weaker at GHz frequencies, which means the brand new system might discover use in functions the place noise is a selected drawback, corresponding to quantum sign processing.
Marric Stephens is a Corresponding Editor for Physics Journal primarily based in Bristol, UK.
- X. Han et al., “Superconducting cavity electromechanics: The conclusion of an acoustic frequency comb at microwave frequencies,” Phys. Rev. Lett. 129, 107701 (2022).