5,466 research outputs found
Observation of slow light in the noise spectrum of a vertical external cavity surface emitting laser
The role of coherent population oscillations is evidenced in the noise
spectrum of an ultra-low noise lasers. This effect is isolated in the intensity
noise spectrum of an optimized single-frequency vertical external cavity
surface emitting laser. The coherent population oscillations induced by the
lasing mode manifest themselves through their associated dispersion that leads
to slow light effects probed by the spontaneous emission present in the
non-lasing side modes.Comment: accepted for publication in Phys. Rev. Let
Quantum System Identification by Bayesian Analysis of Noisy Data: Beyond Hamiltonian Tomography
We consider how to characterize the dynamics of a quantum system from a
restricted set of initial states and measurements using Bayesian analysis.
Previous work has shown that Hamiltonian systems can be well estimated from
analysis of noisy data. Here we show how to generalize this approach to systems
with moderate dephasing in the eigenbasis of the Hamiltonian. We illustrate the
process for a range of three-level quantum systems. The results suggest that
the Bayesian estimation of the frequencies and dephasing rates is generally
highly accurate and the main source of errors are errors in the reconstructed
Hamiltonian basis.Comment: 6 pages, 3 figure
Family Clustering of Viliuisk Encephalomyelitis in Traditional and New Geographic Regions
Transmission occurs through patient contact; human migration from disease-endemic villages leads to disease emergence in new communities
Toward a global description of the nucleus-nucleus interaction
Extensive systematization of theoretical and experimental nuclear densities
and of optical potential strengths exctracted from heavy-ion elastic scattering
data analyses at low and intermediate energies are presented.The
energy-dependence of the nuclear potential is accounted for within a model
based on the nonlocal nature of the interaction.The systematics indicate that
the heavy-ion nuclear potential can be described in a simple global way through
a double-folding shape,which basically depends only on the density of nucleons
of the partners in the collision.The poissibility of extracting information
about the nucleon-nucleon interaction from the heavy-ion potential is
investigated.Comment: 12 pages,12 figure
Coherent States and Modified de Broglie-Bohm Complex Quantum Trajectories
This paper examines the nature of classical correspondence in the case of
coherent states at the level of quantum trajectories. We first show that for a
harmonic oscillator, the coherent state complex quantum trajectories and the
complex classical trajectories are identical to each other. This congruence in
the complex plane, not restricted to high quantum numbers alone, illustrates
that the harmonic oscillator in a coherent state executes classical motion. The
quantum trajectories are those conceived in a modified de Broglie-Bohm scheme
and we note that identical classical and quantum trajectories for coherent
states are obtained only in the present approach. The study is extended to
Gazeau-Klauder and SUSY quantum mechanics-based coherent states of a particle
in an infinite potential well and that in a symmetric Poschl-Teller (PT)
potential by solving for the trajectories numerically. For the coherent state
of the infinite potential well, almost identical classical and quantum
trajectories are obtained whereas for the PT potential, though classical
trajectories are not regained, a periodic motion results as t --> \infty.Comment: More example
Multipurpose High Frequency Electron Spin Resonance Spectrometer for Condensed Matter Research
We describe a quasi-optical multifrequency ESR spectrometer operating in the
75-225 GHz range and optimized at 210 GHz for general use in condensed matter
physics, chemistry and biology. The quasi-optical bridge detects the change of
mm wave polarization at the ESR. A controllable reference arm maintains a mm
wave bias at the detector. The attained sensitivity of 2x10^10 spin/G/(Hz)1/2,
measured on a dilute Mn:MgO sample in a non-resonant probe head at 222.4 GHz
and 300 K, is comparable to commercial high sensitive X band spectrometers. The
spectrometer has a Fabry-Perot resonator based probe head to measure aqueous
solutions, and a probe head to measure magnetic field angular dependence of
single crystals. The spectrometer is robust and easy to use and may be operated
by undergraduate students. Its performance is demonstrated by examples from
various fields of condensed matter physics.Comment: submitted to Journal of Magnetic Resonanc
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