28,579 research outputs found
Microwave-induced resistance oscillations in a back-gated GaAs quantum well
We performed effective mass measurements employing microwave-induced
resistance oscillation in a tunable-density GaAs/AlGaAs quantum well. Our main
result is a clear observation of an effective mass increase with decreasing
density, in general agreement with earlier studies which investigated the
density dependence of the effective mass employing Shubnikov- de Haas
oscillations. This finding provides further evidence that microwave-induced
resistance oscillations are sensitive to electron-electron interactions and
offer a convenient and accurate way to obtain the effective mass.Comment: 4 pages, 4 figure
Secure and privacy-aware proxy mobile IPv6 protocol for vehicle-to-grid networks
Vehicle-to-Grid (V2G) networks have emerged as a new communication paradigm between Electric Vehicles (EVs) and the Smart Grid (SG). In order to ensure seamless communications between mobile EVs and the electric vehicle supply equipment, the support of ubiquitous and transparent mobile IP communications is essential in V2G networks. However, enabling mobile IP communications raises real concerns about the possibility of tracking the locations of connected EVs through their mobile IP addresses. In this paper, we employ certificate-less public key cryptography in synergy with the restrictive partially blind signature technique to construct a secure and privacy-aware proxy mobile IPv6 (SP-PMIPv6) protocol for V2G networks. SP-PMIPv6 achieves low authentication latency while protecting the identity and location privacy of the mobile EV. We evaluate the SP-PMIPv6 protocol in terms of its authentication overhead and the information-theoretic uncertainty derived by the mutual information metric to show the high level of achieved anonymity
Quantization and Corrections of Adiabatic Particle Transport in a Periodic Ratchet Potential
We study the transport of an overdamped particle adiabatically driven by an
asymmetric potential which is periodic in both space and time. We develop an
adiabatic perturbation theory after transforming the Fokker-Planck equation
into a time-dependent hermitian problem, and reveal an analogy with quantum
adiabatic particle transport. An analytical expression is obtained for the
ensemble average of the particle velocity in terms of the Berry phase of the
Bloch states. Its time average is shown to be quantized as a Chern number in
the deterministic or tight-binding limit, with exponentially small corrections.
In the opposite limit, where the thermal energy dominates the ratchet
potential, a formula for the average velocity is also obtained, showing a
second order dependence on the potential.Comment: 8 page
Nonlinear response of a MgZnO/ZnO heterostructure close to zero bias
We report on magnetotransport properties of a MgZnO/ZnO heterostructure
subjected to weak direct currents. We find that in the regime of overlapping
Landau levels, the differential resistivity acquires a quantum correction
proportional to both the square of the current and the Dingle factor. The
analysis shows that the correction to the differential resistivity is dominated
by a current-induced modification of the electron distribution function and
allows us to access both quantum and inelastic scattering rates.Comment: 4 pages, 3 figure
Geometric entanglement from matrix product state representations
An efficient scheme to compute the geometric entanglement per lattice site
for quantum many-body systems on a periodic finite-size chain is proposed in
the context of a tensor network algorithm based on the matrix product state
representations. It is systematically tested for three prototypical critical
quantum spin chains, which belong to the same Ising universality class. The
simulation results lend strong support to the previous claim [Q.-Q. Shi, R.
Or\'{u}s, J. O. Fj{\ae}restad, and H.-Q. Zhou, New J. Phys \textbf{12}, 025008
(2010); J.-M. St\'{e}phan, G. Misguich, and F. Alet, Phys. Rev. B \textbf{82},
180406R (2010)] that the leading finite-size correction to the geometric
entanglement per lattice site is universal, with its remarkable connection to
the celebrated Affleck-Ludwig boundary entropy corresponding to a conformally
invariant boundary condition.Comment: 4+ pages, 3 figure
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