6,493 research outputs found
High coherent solid-state qubit from a pair of quantum dots
In this letter we propose a scheme to build up high coherent solid-state
quantum bit (qubit) from two coupled quantum dots. Quantum information is
stored in electron-hole pair state with the electron and hole locating in
different dots, and universal quantum gates involving any pair of qubits are
realized by effective coupling interaction via virtually exchanging cavity
photons.Comment: 3 pages, 1 figur
Quantum plateau of Andreev reflection induced by spin-orbit coupling
In this work we uncover an interesting quantum plateau behavior for the
Andreev reflection between a one-dimensional quantum wire and superconductor.
The quantum plateau is achieved by properly tuning the interplay of the
spin-orbit coupling within the quantum wire and its tunnel coupling to the
superconductor. This plateau behavior is justified to be unique by excluding
possible existences in the cases associated with multi-channel quantum wire,
the Blonder-Tinkham-Klapwijk continuous model with a barrier, and lattice
system with on-site impurity at the interface.Comment: 6 pages, 3 figures
Measurement of single electron spin with sub-micron Hall magnetometer
Submicron Hall magnetometry has been demonstrated as an efficient technique
to probe extremely weak magnetic fields. In this letter, we analyze the
possibility of employing it to detect single electron spin. Signal strength and
readout time are estimated and discussed with respect to a number of practical
issues.Comment: 4 pages, 2 figur
Time Domain Computation of a Nonlinear Nonlocal Cochlear Model with Applications to Multitone Interaction in Hearing
A nonlinear nonlocal cochlear model of the transmission line type is studied
in order to capture the multitone interactions and resulting tonal suppression
effects. The model can serve as a module for voice signal processing, it is a
one dimensional (in space) damped dispersive nonlinear PDE based on mechanics
and phenomenology of hearing. It describes the motion of basilar membrane (BM)
in the cochlea driven by input pressure waves. Both elastic damping and
selective longitudinal fluid damping are present. The former is nonlinear and
nonlocal in BM displacement, and plays a key role in capturing tonal
interactions. The latter is active only near the exit boundary (helicotrema),
and is built in to damp out the remaining long waves. The initial boundary
value problem is numerically solved with a semi-implicit second order finite
difference method. Solutions reach a multi-frequency quasi-steady state.
Numerical results are shown on two tone suppression from both high-frequency
and low-frequency sides, consistent with known behavior of two tone
suppression. Suppression effects among three tones are demonstrated by showing
how the response magnitudes of the fixed two tones are reduced as we vary the
third tone in frequency and amplitude. We observe qualitative agreement of our
model solutions with existing cat auditory neural data. The model is thus
simple and efficient as a processing tool for voice signals.Comment: 23 pages,7 figures; added reference
Quantum Dynamics of Mesoscopic Driven Duffing Oscillators
We investigate the nonlinear dynamics of a mesoscopic driven Duffing
oscillator in a quantum regime. In terms of Wigner function, we identify the
nature of state near the bifurcation point, and analyze the transient process
which reveals two distinct stages of quenching and escape. The rate process in
the escape stage allows us to extract the transition rate, which displays
perfect scaling behavior with the driving distance to the bifurcation point. We
numerically determine the scaling exponent, compare it with existing result,
and propose open questions to be resolved.Comment: 4 pages, 4 figures; revised version accepted for publication in EP
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