Eran Segev

Nonlinear dynamics in the resonance line shape of NbN superconducting resonators

In this work we characterize the unusual nonlinear dynamics of the resonance response, exhibited by our NbN superconducting microwave resonators, using different operating conditions. The nonlinear dynamics, occurring at relatively low input powers (2-4 orders of magnitude lower than Nb), and which include among others, bifurcations in the resonance curve, hysteresis loops and resonance frequency shift, are measured herein using varying temperature, applied magnetic field, white noise and rapid frequency sweeps. Based on these measurement results, we consider a hypothesis according to which Josephson junctions forming weak links at the boundaries of the NbN grains are responsible for the observed behavior, and we show that most of the experimental results are qualitatively consistent with such hypothesis.We report on unusual nonlinear dynamics observed in the resonance response of

Quantum nondemolition measurement of discrete Fock states of a nanomechanical resonator

\mathrm{NbN}

Noise-induced intermittency in a superconducting microwave resonator

superconducting microwave resonators. The nonlinear dynamics which occurs at relatively low input powers (2\char21{}4 orders of magnitude lower than Nb) includes among others, jumps in the resonance line shape, hysteresis loops changing direction, and resonance frequency shift. These effects are measured herein using varying input power, applied magnetic field, white noise, and rapid frequency sweeps. Based on these measurement results, we consider a hypothesis according to which local heating of weak links forming at the boundaries of the

Intermodulation gain in nonlinear NbN superconducting microwave resonators

\mathrm{NbN}

Thermal instability and self-sustained modulation in superconducting NbN stripline resonators

grains is responsible for the observed behavior, and we show that most of the experimental results are qualitatively consistent with such a hypothesis.

Novel self-sustained modulation in superconducting stripline resonators

We study theoretically a radio frequency superconducting interference device integrated with a nanomechanical resonator and an LC resonator. By applying adiabatic and rotating-wave approximations, we obtain an effective Hamiltonian that governs the dynamics of the mechanical and LC resonators. Nonlinear terms in this Hamiltonian can be exploited for performing a quantum nondemolition measurement of Fock states of the nanomechanical resonator. We address the feasibility of experimental implementation and show that the nonlinear coupling can be made sufficiently strong to allow the detection of discrete mechanical Fock states.

Intermodulation and parametric amplification in a superconducting stripline resonator integrated with a dc-SQUID

We experimentally and numerically study a NbN superconducting stripline resonator integrated with a microbridge. We find that the response of the system to monochromatic excitation exhibits intermittency, namely, noise-induced jumping between coexisting steady-state and limit-cycle responses. A theoretical model that assumes piecewise linear dynamics yields partial agreement with the experimental findings.

Displacement detection with a vibrating rf superconducting interference device: beating the standard linear limit.

We report the measurement of intermodulation gain greater than unity in NbN superconducting stripline resonators. In the intermodulation measurements we inject two unequal tones into the oscillator—the pump and signal—both lying within the resonance band. At the onset of instability of the reflected pump we obtain a simultaneous gain of both the idler and the reflected signal. The measured gain in both cases can be as high as 15dB.

Escape rate of metastable states in a driven NbN superconducting microwave resonator

We study theoretically and experimentally the response of a microwave superconducting stripline resonator, integrated with a microbridge, to a monochromatic injected signal. We find that there is a certain range of driving parameters in which a novel nonlinear phenomenon emerges, and self-sustained modulation of the reflected power off the resonator is generated by the resonator. A theoretical model which attributes the self-modulation to a thermal instability yields a good agreement with the experimental results.

Unusual Nonlinear Dynamics Observed in NbN Superconducting Microwave Resonators

We study thermal instability in a driven superconducting NbN stripline resonator integrated with a microbridge. A monochromatic input drive is injected into the resonator and the response is measured as a function of the frequency and amplitude of the drive. Inside a certain zone of the frequency-amplitude plane the system has no steady state, and consequently self-sustained modulation of the reflected power off the resonator is generated. A theoretical model, according to which the instability originates by a hotspot forming in the microbridge, exhibits a good quantitative agreement with the experimental results.