Biomedical subjects

B L Altshuler

Publications and source records attributed to B L Altshuler.

5 recordsLinked to original sources

PubMed2002

Quantum transport in parallel magnetic fields: a realization of the Berry-Robnik symmetry phenomenon.

We analyze the magnetoconductance of two-dimensional electron and hole gases subject to a parallel magnetic field. It is shown that, for confining potential wells which are symmetric with respect to spatial inversion, a temperature-dependent weak localization signal exists even in the presence of a magnetic field. Deviations from this symmetry lead to magnetoconductance profiles that contain information on both the geometry of the confining potential and characteristics of the disorder.

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PubMed2002

Coulomb "Blockade" of nuclear spin relaxation in quantum dots.

We study the mechanism of nuclear spin relaxation in quantum dots due to the electron exchange with the 2D gas. We show that the nuclear spin relaxation rate 1/T(1) is dramatically affected by the Coulomb blockade (CB) and can be controlled by gate voltage. In the case of strong spin-orbit (SO) coupling the relaxation rate is maximal in the CB valleys, whereas for the weak SO coupling the maximum of 1/T(1) is near the CB peaks.

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PubMed2002

Coherent electron transport in a Si quantum dot dimer.

We show that the coherence of charge transfer through a weakly coupled double-dot dimer can be determined by analyzing the statistics of the conductance pattern, and does not require a large phase coherence length in the host material. We present an experimental study of the charge transport through a small Si nanostructure, which contains two quantum dots. The transport through the dimer is shown to be coherent. At the same time, one of the dots is strongly coupled to the leads, and the overall transport is dominated by inelastic cotunneling processes.

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PubMed2001

Conductance peak motion due to a magnetic field in weakly coupled chaotic quantum dots.

We study the influence of moderate exchange interactions on the behavior of the peaks in the conductance of single electron transistors. We numerically reproduce recently observed features of the magnetic field dependence of both the peak positions and heights. These features unambiguously identify the total spin S of each ground state. We evaluate the probability of each S as a function of the exchange strength J, and external magnetic field B. The expressions involve only J and the g factor as adjustable parameters. For a broad parameter range these probabilities are determined by a linear combination of J and gB.

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PubMed2001

Kondo temperature for the two-channel Kondo models of tunneling centers.

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 all of the intermediate states are taken into account. Prefactor in T(K) is shown to be determined by the spacing between the second and the third levels epsilon(3) in DWP rather than by the electron Fermi energy epsilon(F). Since epsilon(3)<<epsilon(F) there is no microscopic model of movable defects which may justify 2CK phenomenology.

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