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Oscillations cohérentes dans un circuit quantique supraconducteur : le SQUID dc

Abstract : A current-biased dc SQUID behaves as a quantum particle trapped in a cubic-quadratic potential well defined by its bottom well frequency and a finite escape barrier. The energy spectrum of the system is quantified; both position and tunnel lifetime of energy levels are controlled by the bias current and the applied magnetic flux.

During this PhD, an analysis of the escape of the ground state by macroscopic quantum tunnelling (MQT) leads to a characterization of noises acting on bias parameters. MQT is also fundamental for the measurement of the quantum state of the circuit, realized with nanosecond dc flux pulses. Coherent dynamics, induced by resonant microwave flux pulses, is the first step towards a coherent manipulation of the quantum state of the circuit. Finally, incoherent processes were quantitavely studied in the two level limit, using low power spectroscopy and energy relaxation measurements.
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Contributor : Julien Claudon <>
Submitted on : Wednesday, January 18, 2006 - 10:25:11 AM
Last modification on : Friday, December 18, 2020 - 1:34:03 PM
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  • HAL Id : tel-00011407, version 1




Julien Claudon. Oscillations cohérentes dans un circuit quantique supraconducteur : le SQUID dc. Supraconductivité [cond-mat.supr-con]. Université Joseph-Fourier - Grenoble I, 2005. Français. ⟨tel-00011407⟩



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