arXiv subjects

Baleegh Abdo

Publications and source records attributed to Baleegh Abdo.

33 records · Page 2Linked to original sources

arXiv2009

Intermode Dephasing in a Superconducting Stripline Resonator - Supplementary Information

Supplementary information for the article "Intermode Dephasing in a Superconducting Stripline Resonator" (arXiv:0901.3110). The supplementary information is devoted to three main issues. In section I we describe the fabrication process; in section II we present the derivation of the Hamiltonian of the system and provide a more detailed discussion about the properties of the microbridges; in section III the hysteretic response of the resonator and the effect of heating are discussed.

cond-mat.supr-con↗

arXiv2008

Phase sensitive amplification in a superconducting stripline resonator integrated with a dc-SQUID

We utilize a superconducting stripline resonator containing a dc-SQUID as a strong intermodulation amplifier exhibiting a signal gain of 25 dB and a phase modulation of 30 dB. Studying the system response in the time domain near the intermodulation amplification threshold reveals a unique noise-induced spikes behavior. We account for this response qualitatively via solving numerically the equations of motion for the integrated system. Furthermore, employing this device as a parametric amplifier yields a gain of 38 dB in the generated side-band signal.

cond-mat.supr-con↗

arXiv2007

Quantum Nondemolition Measurement of Discrete Fock States of a Nanomechanical Resonator

We study theoretically a radio frequency superconducting interference device integrated with both a nanomechanical resonator and an LC one. 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.

quant-ph↗

arXiv2007

Stochastic Resonance with a Single Metastable State

We study thermal instability in NbN superconducting stripline resonators. The system exhibits extreme nonlinearity near a bifurcation, which separates a monostable zone and an astable one. The lifetime of the metastable state, which is locally stable in the monostable zone, is measure near the bifurcation and the results are compared with a theory. Near bifurcation, where the lifetime becomes relatively short, the system exhibits strong amplification of a weak input modulation signal. We find that the frequency bandwidth of this amplification mechanism is limited by the rate of thermal relaxation. When the frequency of the input modulation signal becomes comparable or larger than this rate the response of the system exhibits sub-harmonics of various orders.

cond-mat.supr-con↗

arXiv2007

Displacement Detection with a Vibrating RF SQUID: Beating the Standard Linear Limit

We study a novel configuration for displacement detection consisting of a nanomechanical resonator coupled to both, a radio frequency superconducting interference device (RF SQUID) and to a superconducting stripline resonator. We employ an adiabatic approximation and rotating wave approximation and calculate the displacement sensitivity. We study the performance of such a displacement detector when the stripline resonator is driven into a region of nonlinear oscillations. In this region the system exhibits noise squeezing in the output signal when homodyne detection is employed for readout. We show that displacement sensitivity of the device in this region may exceed the upper bound imposed upon the sensitivity when operating in the linear region. On the other hand, we find that the high displacement sensitivity is accompanied by a slowing down of the response of the system, resulting in a limited bandwidth.

cond-mat.mes-hall↗

arXiv2006

Novel Self-Sustained Modulation in Superconducting Stripline Resonators

We study thermal instability in a driven superconducting NbN 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 in 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 hot spot forming in the microbridge, exhibits a good quantitative agreement with the experimental results.

cond-mat.supr-con↗

arXiv2006

Thermal Instability and Self-Sustained Modulation in Superconducting NbN Stripline Resonators

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 immerges, 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.

cond-mat.supr-con↗

arXiv2006

Prospects of employing superconducting stripline resonators for studying the dynamical Casimir effect experimentally

We discuss the prospects of employing an NbN superconducting microwave stripline resonator for studying the dynamical Casimir effect experimentally. Preliminary experimental results, in which optical illumination is employed for modulating the resonance frequencies of the resonator, show that such a system is highly promising for this purpose. Moreover, we discuss the undesirable effect of heating which results from the optical illumination, and show that degradation in noise properties can be minimized by employing an appropriate design.

quant-ph↗

arXiv2006

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

We study thermal instability and formation of local hot spots in a driven nonlinear NbN superconducting microwave resonator. White noise injected into the resonator results in transitions between the metastable states via a process consisting of two stages. In the first stage, the input noise entering the system induces fluctuations in the resonator mode. While, in the second one, these mode fluctuations result in phase transitions of the hot spot due to induced temperature fluctuations. The associated noise-activated escape rate is calculated theoretically, and also measured experimentally by means of driving the system into stochastic resonance. A comparison between theory and experiment yields a partial agreement.

cond-mat.stat-mech↗

arXiv2006

Extreme Nonlinear Phenomena in NbN Superconducting Stripline Resonators

We study a microwave superconducting stripline resonator made of NbN on a Sapphire wafer. Novel, self-sustained modulation of the reflected power off the resonator, at frequencies of up to 60MHz, has been recently reported. Here we show experimentally that near the self modulation threshold, the device exhibits a giant nonlinearity, which manifests itself in an extremely high intermodulation gain, accompanied by a very strong noise squeezing and period doubling of various orders. Such a device is highly suitable for serving as a readout device in quantum data processing systems.

cond-mat.supr-con↗

arXiv2006

Signal Amplification in NbN Superconducting Resonators via Stochastic Resonance

We exploit nonlinearity in NbN superconducting stripline resonators, which is originated by local thermal instability, for studying stochastic resonance. As the resonators are driven into instability, small amplitude modulated (AM) microwave signals are amplified with the aid of injected white noise. The dependence of the signal amplification on the modulation amplitude and the modulation frequency is examined and compared with theory.

cond-mat.supr-con↗

arXiv2006

Fast Resonance Frequency Modulation in Superconducting Stripline Resonator

Fast resonance frequency modulation of a superconducting stripline resonator is investigated. The experiments are performed using a novel device which integrates a hot electron detector (HED) into a superconducting stripline ring resonator. Frequency modulation is demonstrated by both applying dc current or voltage to the HED, and by applying optical illumination, with modulation frequencies of up to 4.2GHz. Potential applications for such a device are in telecommunication, quantum cryptography and biofluorescence.

cond-mat.supr-con↗

arXiv2005

Unexpected Nonlinear Dynamics in NbN Superconducting Microwave 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.

cond-mat.supr-con↗

arXiv2005

Nonlinear Coupling in Nb/NbN Superconducting Microwave Resonators

In this experimental study we show that the coupling between Nb/NbN superconducting microwave resonators and their feedline can be made amplitude dependent. We employ this mechanism to tune the resonators into critical coupling condition, a preferable mode of operation for a wide range of applications. Moreover we examine the dependence of critical coupling state on other parameters such as temperature and magnetic field. Possible novel applications based on such nonlinear coupling are briefly discussed.

cond-mat.supr-con↗

arXiv2005

Observation of Bifurcations and Hysteresis in Nonlinear NbN Superconducting Microwave Resonators

In this paper we report some extraordinary nonlinear dynamics measured in the resonance curve of NbN superconducting stripline microwave resonators. Among the nonlinearities observed: aburpt bifurcations in the resonance response at relatively low input powers, asymmetric resonances, multiple jumps within the resonance band, resonance frequency drift, frequency hysteresis, hysteresis loops changing direction and critical coupling phenomenon. Weak links in the NbN grain structure are hypothesized as the source of the nonlinearities.

cond-mat.supr-con↗