8,449 research outputs found
Solitonic dispersive hydrodynamics: theory and observation
Ubiquitous nonlinear waves in dispersive media include localized solitons and
extended hydrodynamic states such as dispersive shock waves. Despite their
physical prominence and the development of thorough theoretical and
experimental investigations of each separately, experiments and a unified
theory of solitons and dispersive hydrodynamics are lacking. Here, a general
soliton-mean field theory is introduced and used to describe the propagation of
solitons in macroscopic hydrodynamic flows. Two universal adiabatic invariants
of motion are identified that predict trapping or transmission of solitons by
hydrodynamic states. The result of solitons incident upon smooth expansion
waves or compressive, rapidly oscillating dispersive shock waves is the same,
an effect termed hydrodynamic reciprocity. Experiments on viscous fluid
conduits quantitatively confirm the soliton-mean field theory with broader
implications for nonlinear optics, superfluids, geophysical fluids, and other
dispersive hydrodynamic media.Comment: 8 pages, 5 figure
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Single-shot optical conductivity measurement of dense aluminum plasmas
The optical conductivity of a dense femtosecond laser-heated aluminum plasma heated to 0.1-1.5 eV was measured using frequency-domain interferometry with chirped pulses, permitting simultaneous observation of optical probe reflectivity and probe pulse phase shift. Coupled with published models of bound-electron contributions to the conductivity, these two independent experimental data yielded a direct measurement of both real and imaginary components of the plasma conductivity.DOE National Nuclear Security Administration DE-FC52-03NA00156Physic
Synchronized pulse control of decoherence
We present a new strategy for multipulse control over decoherence. When a
two-level system interacts with a reservoir characterized by a specific
frequency, we find that the decoherence is effectively suppressed by
synchronizing the pulse-train application with the dynamical motion of the
reservoir.Comment: 14 pages, 8 figure
Decoherence Rates in Large Scale Quantum Computers and Macroscopic Systems
Markovian regime decoherence effects in quantum computers are studied in
terms of the fidelity for the situation where the number of qubits N becomes
large. A general expression giving the decoherence time scale in terms of
Markovian relaxation elements and expectation values of products of system
fluctuation operators is obtained, which could also be applied to study
decoherence in other macroscopic systems such as Bose condensates and
superconductors. A standard circuit model quantum computer involving
three-state lambda system ionic qubits is considered, with qubits localised
around well-separated positions via trapping potentials. The centre of mass
vibrations of the qubits act as a reservoir. Coherent one and two qubit gating
processes are controlled by time dependent localised classical electromagnetic
fields that address specific qubits, the two qubit gating processes being
facilitated by a cavity mode ancilla, which permits state interchange between
qubits. With a suitable choice of parameters, it is found that the decoherence
time can be made essentially independent of N.Comment: Minor revisions. To be published in J Mod Opt. One figur
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