Journal ArticleDOI
Quantum Mechanics of a Macroscopic Variable: The Phase Difference of a Josephson Junction
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TLDR
Low temperature measurements of the escape rate for junctions that are either nearly undamped or moderately damped agree very closely with predictions for macroscopic quantum tunneling, with no adjustable parameters.Abstract:
Experiments to investigate the quantum behavior of a macroscopic degree of freedom, namely the phase difference across a Josephson tunnel junction, are described. The experiments involve measurements of the escape rate of the junction from its zero voltage state. Low temperature measurements of the escape rate for junctions that are either nearly undamped or moderately damped agree very closely with predictions for macroscopic quantum tunneling, with no adjustable parameters. Microwave spectroscopy reveals quantized energy levels in the potential well of the junction in excellent agreement with quantum-mechanical calculations. The system can be regarded as a "macroscopic nucleus with wires."read more
Citations
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Reaction-rate theory: fifty years after Kramers
TL;DR: In this paper, the authors report, extend, and interpret much of our current understanding relating to theories of noise-activated escape, for which many of the notable contributions are originating from the communities both of physics and of physical chemistry.
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Quantum-state engineering with Josephson-junction devices
TL;DR: In this article, the authors review the properties of low-capacitance Josephson tunneling junctions and the practical and fundamental obstacles to their use for quantum information processing and describe how the basic physical manipulations on an ideal device can be combined to perform useful operations.
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Quantum ground state and single-phonon control of a mechanical resonator
A. D. O’Connell,Max Hofheinz,Markus Ansmann,Radoslaw C. Bialczak,M. Lenander,Erik Lucero,Matthew Neeley,Daniel Sank,Haohua Wang,Martin Weides,James Wenner,John M. Martinis,Andrew Cleland +12 more
TL;DR: This work shows that conventional cryogenic refrigeration can be used to cool a mechanical mode to its quantum ground state by using a microwave-frequency mechanical oscillator—a ‘quantum drum’—coupled to a quantum bit, which is used to measure the quantum state of the resonator.
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Quantum superposition of distinct macroscopic states
TL;DR: Experimental evidence is presented that a superconducting quantum interference device (SQUID) can be put into a superposition of two magnetic-flux states: one corresponding to a few microamperes of current flowing clockwise, the other corresponding to the same amount ofCurrent flowing anticlockwise.
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Wiring up quantum systems
Robert Schoelkopf,Steven Girvin +1 more
TL;DR: The emerging field of circuit quantum electrodynamics could pave the way for the design of practical quantum computers, according to researchers at the Massachusetts Institute of Technology.
References
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Brownian motion in a field of force and the diffusion model of chemical reactions
TL;DR: In this article, a particle which is caught in a potential hole and which, through the shuttling action of Brownian motion, can escape over a potential barrier yields a suitable model for elucidating the applicability of the transition state method for calculating the rate of chemical reactions.
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Quantum tunnelling in a dissipative system
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Supercurrents through barriers
TL;DR: In this paper, a phenomenological theory was developed and applied to a number of topics, such as penetration of a magnetic field into a barrier, interference of supercurrents in the presence of magnetic field, the cut-off frequency associated with the propagation of electromagnetic waves along a barrier and structure in the d.c. supercurrent.
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Quantum Statistical Metastability
TL;DR: In this article, a general theory of metastability is constructed in which these formulas are true for temperatures, respectively, below and above the saddle point of a system rendered unstable by both quantum tunneling and thermodynamic fluctuation.