76,529 research outputs found
Non-Hermitian coherent coupling of nanomagnets by exchange spin waves
Non-Hermitian physics has recently attracted much attention in optics and
photonics. Less explored is non-Hermitian magnonics that provides opportunities
to take advantage of the inevitable dissipation of magnons or spin waves in
magnetic systems. Here we demonstrate non-Hermitian coherent coupling of two
distant nanomagnets by fast spin waves with sub-50 nm wavelengths. Magnons in
two nanomagnets are unidirectionally phase-locked with phase shifts controlled
by magnon spin torque and spin-wave propagation. Our results are attractive for
analog neuromorphic computing that requires unidirectional information
transmission
Solutions to the Jaynes-Cummings model without the rotating-wave approximation
By using extended bosonic coherent states, the solution to the
Jaynes-Cummings model without the rotating-wave approximation can be mapped to
that of a polynomial equation with a single variable. The solutions to this
polynomial equation can give all eigenvalues and eigenfunctions of this model
with all values of the coupling strength and the detuning exactly, which can be
readily applied to recent circuit quantum electrodynamic systems operating in
the ultra-strong coupling regime.Comment: 6 pages,3 figure
Realization of universal quantum cloning with SQUID qubits in a cavity
We propose a scheme to realize universal quantum cloning machine
(UQCM) with superconducting quantum interference device (SQUID) qubits, embeded
in a high-Q cavity. CNOT operations are derived to present our scheme, and the
two-photon Raman resonance processes are used to increase the operation rate.
Compared with previous works, our scheme has advantages in the experimental
realization and further utilization.Comment: 4 pages, 2 figure
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Influence of convection and biomass burning outflow on tropospheric chemistry over the tropical Pacific
Observations over the tropics from the Pacific Exploratory Mission-Tropics A Experiment are analyzed using a one-dimensional model with an explicit formulation for convective transport. Adopting tropical convective mass fluxes from a general circulation model (GCM) yields a large discrepancy between observed and simulated CH3I concentrations. Observations of CH3I imply the convective mass outflux to be more evenly distributed with altitude over the tropical ocean than suggested by the GCM. We find that using a uniform convective turnover lifetime of 20 days in the upper and middle troposphere enables the model to reproduce CH3I observations. The model reproduces observed concentrations of H2O2 and CH3OOH. Convective transport of CH3OOH from the lower troposphere is estimated to account for 40-80% of CH3OOH concentrations in the upper troposphere. Photolysis of CH3OOH transported by convection more than doubles the primary HOx source and increases OH concentrations and O3 production by 10-50% and 0.4 ppbv d-1, respectively, above 11 km. Its effect on the OH concentration and O3 production integrated over the tropospheric column is, however, small. The effects of pollutant import from biomass burning regions are much more dominant. Using C2H2 as a tracer, we estimate that biomass burning outflow enhances O3 concentrations, O3 production, and concentrations of NOx and OH by 60%, 45%, 75%, and 7%, respectively. The model overestimates HNO3 concentrations by about a factor of 2 above 4 km for the upper one-third quantile of C2H2 data while it generally reproduces HNO3 concentrations for the lower and middle one-third quantiles of C2H2 data. Copyright 2000 by the American Geophysical Union
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