17,476 research outputs found
A frequency-domain approach to the analysis of stability and bifurcations in nonlinear systems described by differential-algebraic equations
A general numerical technique is proposed for the assessment of the stability of periodic solutions and the determination of bifurcations for limit cycles in autonomous nonlinear systems represented by ordinary differential equations in the differential-algebraic form. The method is based on the harmonic balance technique, and exploits the same Jacobian matrix of the nonlinear system used in the Newton iterative numerical solution of the harmonic balance equations for the determination of the periodic steady-state. To demonstrate the approach, it is applied to the determination of the bifurcation curves in the parameters' space of Chua's circuit with cubic nonlinearity, and to study the dynamics of the limit cycle of a Colpitts oscillato
Index to NASA Tech Briefs, 1975
This index contains abstracts and four indexes--subject, personal author, originating Center, and Tech Brief number--for 1975 Tech Briefs
Josephson Vortex Qubit based on a Confocal Annular Josephson Junction
We report theoretical and experimental work on the development of a Josephson
vortex qubit based on a confocal annular Josephson tunnel junction (CAJTJ). The
key ingredient of this geometrical configuration is a periodically variable
width that generates a spatial vortex potential with bistable states. This
intrinsic vortex potential can be tuned by an externally applied magnetic field
and tilted by a bias current. The two-state system is accurately modeled by a
one-dimensional sine-Gordon like equation by means of which one can numerically
calculate both the magnetic field needed to set the vortex in a given state as
well as the vortex depinning currents. Experimental data taken at 4.2K on
high-quality Nb/Al-AlOx/Nb CAJTJs with an individual trapped fluxon advocate
the presence of a robust and finely tunable double-well potential for which
reliable manipulation of the vortex state has been classically demonstrated.
The vortex is prepared in a given potential by means of an externally applied
magnetic field, while the state readout is accomplished by measuring the
vortex-depinning current in a small magnetic field. Our proof of principle
experiment convincingly demonstrates that the proposed vortex qubit based on
CAJTJs is robust and workable.Comment: 20 pages, 11 figure
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