Yu M Galperin

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The Rashba and Dresselhaus spin-orbit interactions are both shown to yield the low temperature spin-Hall effect for strongly localized electrons coupled to phonons. A frequency-dependent electric field E(omega) generates a spin-polarization current, normal to E, due to interference of hopping paths. At zero temperature the corresponding spin-Hall(More)
A theoretical interpretation of the recent experiments of Astafiev et al. on the T1-relaxation rate in Josephson charge qubits is proposed. The experimentally observed reproducible nonmonotonic dependence of T1 on the splitting E(J) of the qubit levels suggests further specification of the previously proposed models of the background charge noise. From our(More)
We study the entropy and information flow in a Maxwell-demon device based on a single-electron transistor with controlled gate potentials. We construct the protocols for measuring the charge states and manipulating the gate voltages, which minimizes irreversibility for (i) constant input power from the environment or (ii) given energy gain. Charge(More)
We study decoherence in a qubit with the distance between the two levels affected by random flips of bistable fluctuators. For the case of a single fluctuator we evaluate explicitly an exact expression for the phase-memory decay in the echo experiment with a resonant ac excitation. The echo signal as a function of time shows a sequence of plateaus. The(More)
J. I. Vestgården,1 J. Bergli,1 and Y. M. Galperin1,2,3 1Department of Physics and Center for Advanced Materials and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, 0316 Oslo, Norway 2A. F. Ioffe Physico-Technical Institute of Russian Academy of Sciences, 194021 St. Petersburg, Russia 3Argonne National Laboratory, 9700 S. Cass Avenue, Argonne,(More)
A two-channel Kondo (2CK) non-Fermi liquid state in a metal resulting from the interaction between electrons and structural defects modeled by double-well potentials (DWP) is revisited. Account only of the two lowest states in DWP is known to lead to rather low Kondo temperature, T(K). We prove that the contribution of higher excited states reduces T(K), if(More)
We report on the first spatially resolved observation of mesoscopic flux jumps in superconducting films. Magnetooptical imaging was used to visualize the flux penetration in MgB2 films subjected to a slowly varying perpendicular field. Below 10 K, flux jumps with typical size 10-20 microns and regular shape are found to occur at random locations along the(More)
– Magneto-optical imaging reveal that below 10 K the penetration of magnetic flux in MgB2 films is dominated by dendritic structures abruptly formed in response to an applied field. The dendrites show a temperature-dependent morphology ranging from quasi-1D at 4 K to large tree-like structures near 10 K. This behaviour is responsible for the anomalous noise(More)
Superconducting circuits that incorporate Josephson junctions are of considerable experimental and theoretical interest, particularly in the context of quantum computing. A nanometre-sized superconducting grain (commonly referred to as a Cooper-pair box) connected to a reservoir by a Josephson junction is an important example of such a system. Although the(More)