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In superconducting qubits, the interaction of the qubit degree of freedom with quasiparticles defines a fundamental limitation for the qubit coherence. We develop a theory of the pure dephasing rate \Gamma_{\phi} caused by quasiparticles…

Mesoscale and Nanoscale Physics · Physics 2012-11-22 G. Catelani , Simon E. Nigg , S. M. Girvin , R. J. Schoelkopf , L. I. Glazman

We present a method for the study of quantum fluctuations of dissipative structures forming in nonlinear optical cavities, which we illustrate in the case of a degenerate, type I optical parametric oscillator. The method consists in (i)…

Quantum Physics · Physics 2007-07-31 Isabel Perez-Arjona , Eugenio Roldan , German J. de Valcarcel

We revisit dipolar motion of condensate atoms in one-dimensional optical lattices and harmonic magnetic traps including quantum fluctuations within the truncated Wigner approximation. In the strong tunneling limit we reproduce the meanfield…

Soft Condensed Matter · Physics 2007-05-23 Anatoli Polkovnikov , Daw-Wei Wang

We have realized controllable coupling between two three-junction flux qubits by inserting an additional coupler loop between them, containing three Josephson junctions. Two of these are shared with the qubit loops, providing strong…

We have detected coherent quantum oscillations between Josephson phase qubits and microscopic critical-current fluctuators by implementing a new state readout technique that is an order of magnitude faster than previous methods. The period…

The fluctuating superconducting correlations emerging in dirty hybrid structures in conditions of the strong proximity effect are demonstrated to affect the validity range of the widely used formalism of Usadel equations at mesoscopic…

Superconductivity · Physics 2016-10-12 A. S. Mel'nikov , A. I. Buzdin

We consider a driven quantum particle in the strong friction regime described by the quantum Smoluchowski equation. We derive Crooks and Jarzynski type relations for the reduced quantum system by properly generalizing the entropy production…

Statistical Mechanics · Physics 2011-04-27 Sebastian Deffner , Michael Brunner , Eric Lutz

High quality factors, strong nonlinearities, and extensive design flexibility make superconducting circuits an ideal platform to investigate synchronization phenomena deep in the quantum regime. Recently~\cite{Loerch-2017}, it was predicted…

Quantum Physics · Physics 2018-01-11 Simon E. Nigg

The influence of fluctuations and periodical driving on temporal characteristics of short overdamped Josephson junction is analyzed. We obtain the standard deviation of the switching time in the presence of a dichotomous driving force for…

Statistical Mechanics · Physics 2009-11-10 Andrey L. Pankratov , Bernardo Spagnolo

Josephson junctions form the essential non-linearity for almost all superconducting qubits. The junction is formed when two superconducting electrodes come within $\sim$1 nm of each other. Although the capacitance of these electrodes is a…

The theory of current transport in a narrow superconducting channel accounting for thermal fluctuations is developed. These fluctuations result in the appearance of small but finite dissipation in the sample. The value of corresponding…

Superconductivity · Physics 2009-10-15 Yu. N. Ovchinnikov , A. A. Varlamov

We investigated decoherence of a Josephson vortex quantum bit (qubit) in dissipative and noisy environment. As the Josephson vortex qubit (JVQ) is fabricated by using a long Josephson junction (LJJ), we use the perturbed sine-Gordon…

Superconductivity · Physics 2009-11-11 Ju H. Kim , Ramesh P. Dhungana , Kee-Su Park

The shape of experimentally observed R(T) transition of thin superconducting wires is analyzed. Broadening of the transition in quasi-1-dimensional superconducting channels is typically associated with phase slip mechanism provided by…

Superconductivity · Physics 2009-04-07 M. Zgirski , K. Yu. Arutyunov

We consider the current fluctuations in a mesoscopic circuit consisting of nodes connected by arbitrary connectors, in a setup with multiple normal or superconducting terminals. In the limit of weak superconducting proximity effect,…

Superconductivity · Physics 2007-05-23 P. Virtanen , T. T. Heikkila

Arrays of Josephson junctions are at the forefront of research on quantum circuitry for quantum computing, simulation and metrology. They provide a testing bed for exploring a variety of fundamental physical effects where macroscopic phase…

The topic of quantum fluctuations in quasi-1D superconductors, also called quantum phase slips (QPS), has attracted a significant attention. It has been shown that the phenomenon is capable to suppress zero resistivity of ultra-narrow…

Mesoscale and Nanoscale Physics · Physics 2013-11-14 J. S. Lehtinen , T. Rantala , K. Yu. Arutyunov

Nonequilibrium effects in layered superconductors forming a stack of intrinsic Josephson junctions are investigated. We discuss two basic nonequilibrium effects caused by charge fluctuations on the superconducting layers: a) the shift of…

Superconductivity · Physics 2009-11-07 D. A. Ryndyk , J. Keller , C. Helm

We study staggered flux fluctuations around the superconducting state of the SU(2) meanfield theory for the two-dimensional t-J-model and their effect on the electron spectral function. The quasiparticle peaks near the saddlepoints get…

Strongly Correlated Electrons · Physics 2009-11-07 Carsten Honerkamp , Patrick A. Lee

We find that the upper critical field in a two-dimensional disordered superconductor can increase essentially at low temperatures. This happens due to the formation of local superconducting islands weakly coupled via the Josephson effect.…

Superconductivity · Physics 2009-11-07 Victor Galitski , A. I. Larkin

We investigate the transport properties of open quantum chaotic systems in the semiclassical limit. We show how the transmission spectrum, the conductance fluctuations, and their correlations are influenced by the underlying chaotic…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Ph. Jacquod , E. V. Sukhorukov