arXiv subjects

A. Kamenev

Publications and source records attributed to A. Kamenev.

25 records · Page 2Linked to original sources

arXiv2004

Weak dynamical localization in periodically kicked cold atomic gases

Quantum kicked rotor was recently realized in experiments with cold atomic gases and standing optical waves. As predicted, it exhibits dynamical localization in the momentum space. Here we consider the weak localization regime concentrating on the Ehrenfest time scale. The later accounts for the spread-time of a minimal wavepacket and is proportional to the logarithm of the Planck constant. We show that the onset of the dynamical localization is essentially delayed by four Ehrenfest times and give quantitative predictions suitable for an experimental verification.

cond-mat.mes-hall↗

arXiv2002

Coulomb Blockade with Dispersive Interfaces

What quantity controls the Coulomb blockade oscillations if the dot--lead conductance is essentially frequency--dependent ? We argue that it is the ac dissipative conductance at the frequency given by the effective charging energy. The latter may be very different from the bare charging energy due to the interface--induced capacitance (or inductance). These observations are supported by a number of examples, considered from the weak and strong coupling (perturbation theory vs. instanton calculus) perspectives.

cond-mat.mes-hall↗

arXiv2002

Weak Charge Quantization on Superconducting Islands

We consider the Coulomb blockade on a superconductive quantum dot strongly coupled to a lead through a tunnelling barrier and/or normal diffusive metal. Andreev transport of the correlated pairs leads to quantum fluctuations of the charge on the dot. These fluctuations result in exponential renormalization of the effective charging energy. We employ two complimentary ways to approach the problem, leading to the coinciding results: the instanton and the functional RG treatment of the non-linear sigma model. We also derive the charging energy renormalization in terms of arbitrary transmission matrix of the multi-channel interface.

cond-mat.mes-hall↗

arXiv2000

Quantum Pumping in the Magnetic Field: Role of Discrete Symmetries

We consider an effect of the discrete spatial symmetries and magnetic field on the adiabatic charge pumping in mesoscopic systems. In general case, there is no symmetry of the pumped charge with respect to the inversion of magnetic field Q(B) \neq Q(-B). We find that the reflection symmetries give rise to relations Q(B)=Q(-B) or Q(B)=-Q(-B) depending on the orientation of the reflection axis. In presence of the center of inversion, Q(B) = 0. Additional symmetries may arise in the case of bilinear pumping.

cond-mat.mes-hall↗

arXiv1996

Quasiparticle Lifetime in a Finite System: A Non--Perturbative Approach

The problem of electron--electron lifetime in a quantum dot is studied beyond perturbation theory by mapping it onto the problem of localization in the Fock space. We identify two regimes, localized and delocalized, corresponding to quasiparticle spectral peaks of zero and finite width, respectively. In the localized regime, quasiparticle states are very close to single particle excitations. In the delocalized state, each eigenstate is a superposition of states with very different quasiparticle content. A transition between the two regimes occurs at the energy $\simeqΔ(g/\ln g)^{1/2}$, where $Δ$ is the one particle level spacing, and $g$ is the dimensionless conductance. Near this energy there is a broad critical region in which the states are multifractal, and are not described by the Golden Rule.

cond-mat↗

arXiv1994

Resonance Magnetoresistance in Coupled Quantum Wells

The in-plane magnetic field suppresses the quantum coupling between electrons in a double quantum well structure. The microscopical theory of this effect is developed and confirmed experimentally. We have shown that the decrease of the "resistance resonance" peak is sensitive to the mutual orientation of the current and the in-plane magnetic field. The characteristic field required for the suppression of the resonance depends on the elastic small angle and electron--electron scattering rates. The study of the characteristic field allows to verify the temperature and Fermi energy dependence of the electron--electron scattering rate, providing a new experimental tool for its measurement.

cond-mat↗

arXiv1994

Resonant Transport in Coupled Quantum Wells: a Probe for Scattering Mechanisms

We present a microscopical theory and experimental results concerning resistance resonance in two tunneling coupled quantum wells with different mobilities. The shape of the resonance appears to be sensitive to the small angle scattering rate on remote impurities and to the electron--electron scattering rate. This allows the extraction of scattering parameters directly from the transport measurements. The negative resonance in a Hall coefficient is predicted and observed for the first time.

cond-mat↗