14,074 research outputs found
The energy level structure of a variety of one-dimensional confining potentials and the effects of a local singular perturbation
Motivated by current interest in quantum confinement potentials, especially
with respect to the Stark spectroscopy of new types of quantum wells, we
examine several novel one-dimensional singular oscillators. A Green function
method is applied, the construction of the necessary resolvents is reviewed and
several new ones are introduced. In addition, previous work on the singular
harmonic oscillator model, introduced by Avakian et al. is reproduced to verify
the method and results. A novel features is the determination of the spectra of
asymmetric hybrid linear and quadratic potentials. As in previous work, the
singular perturbations are modeled by delta functions.Comment: 14 pages, 10 figure
General Approach to Functional Forms for the Exponential Quadratic Operators in Coordinate-Momentum Space
In a recent paper [Nieto M M 1996 Quantum and Semiclassical Optics, 8 1061;
quant-ph/9605032], the one dimensional squeezed and harmonic oscillator
time-displacement operators were reordered in coordinate-momentum space. In
this paper, we give a general approach for reordering multi-dimensional
exponential quadratic operator(EQO) in coordinate-momentum space. An explicit
computational formula is provided and applied to the single mode and
double-mode EQO through the squeezed operator and the time displacement
operator of the harmonic oscillator.Comment: To appear in J. Phys. A: Mathematics and Genera
Husimi function and phase-space analysis of bilayer quantum Hall systems at
We propose localization measures in phase space of the ground state of
bilayer quantum Hall (BLQH) systems at fractional filling factors
, to characterize the three quantum phases (shortly denoted by
spin, canted and ppin) for arbitrary -isospin . We use a
coherent state (Bargmann) representation of quantum states, as holomorphic
functions in the 8-dimensional Grassmannian phase-space
(a higher-dimensional generalization
of the Haldane's 2-dimensional sphere ).
We quantify the localization (inverse volume) of the ground state wave function
in phase-space throughout the phase diagram (i.e., as a function of Zeeman,
tunneling, layer distance, etc, control parameters) with the Husimi function
second moment, a kind of inverse participation ratio that behaves as an order
parameter. Then we visualize the different ground state structure in phase
space of the three quantum phases, the canted phase displaying a much higher
delocalization (a Schr\"odinger cat structure) than the spin and ppin phases,
where the ground state is highly coherent. We find a good agreement between
analytic (variational) and numeric diagonalization results.Comment: 13 pages, 6 figures. New section added. Novel results and insights
further highlighte
Neurologic Deficits Including Auditory Loss and Recovery of Function in Horses with Temporohyoid Osteoarthropathy.
BackgroundAuditory loss is a common deficit in horses with temporohyoid osteoarthropathy (THO), however, recovery of function is unknown.Hypothesis/objectivesTo investigate neurologic function with emphasis in audition in horses with THO after treatment. To describe anatomical alterations of the petrous temporal bone that might result in auditory loss.AnimalsTwenty-four horses with a clinical diagnosis of THO.MethodsProspective study. A brainstem auditory evoked response (BAER) study was done as part of the criteria for inclusion in horses with a clinical diagnosis of THO from the years of 2005 to 2014. Physical and neurologic status and BAER findings were recorded. Brainstem auditory evoked response variables were compared by using Wilcoxon sign test. Fisher's exact test was also used. Significance was set at P < 0.05.ResultsThe most common signs included auditory loss (100% of horses), vestibular and facial nerve dysfunction (83%), and exposure ulcerative keratitis (71%). Concurrent left laryngeal hemiparesis was observed in 61% of horses through endoscopy. Auditory dysfunction was bilateral in 50% of the cases (complete and partial), and unilateral affecting more commonly the right ear (R = 8, L = 4). Short- and long-term follow-up revealed persistent auditory loss in all horses based on abnormal response to sound, and further confirmed through a BAER in 8 horses.Conclusions and clinical importanceAuditory dysfunction appears to be a permanent neurologic deficit in horses diagnosed with THO despite overall neurologic improvement
Functional Forms for the Squeeze and the Time-Displacement Operators
Using Baker-Campbell-Hausdorff relations, the squeeze and harmonic-oscillator
time-displacement operators are given in the form , where ,
, , and are explicitly determined. Applications are
discussed.Comment: 10 pages, LaTe
- …