1,912 research outputs found
Supersymmetry and a Time-Dependent Landau System
A general technique is outlined for investigating supersymmetry properties of
a charged spin-\half quantum particle in time-varying electromagnetic fields.
The case of a time-varying uniform magnetic induction is examined and shown to
provide a physical realization of a supersymmetric quantum-mechanical system.
Group-theoretic methods are used to factorize the relevant Schr\"odinger
equations and obtain eigensolutions. The supercoherent states for this system
are constructed.Comment: 47 pages, submitted to Phys. Rev. A, LaTeX, IUHET 243 and
LA-UR-93-20
Comparison of web-based and face-to-face interviews for application to an anesthesiology training program: a pilot study.
ObjectiveThis study compared admission rates to a United States anesthesiology residency program for applicants completing face-to-face versus web-based interviews during the admissions process. We also explored factors driving applicants to select each interview type.MethodsThe 211 applicants invited to interview for admission to our anesthesiology residency program during the 2014-2015 application cycle were participants in this pilot observational study. Of these, 141 applicants selected face-to-face interviews, 53 applicants selected web-based interviews, and 17 applicants declined to interview. Data regarding applicants' reasons for selecting a particular interview type were gathered using an anonymous online survey after interview completion. Residency program admission rates and survey answers were compared between applicants completing face-to-face versus web-based interviews.ResultsOne hundred twenty-seven (75.1%) applicants completed face-to-face and 42 (24.9%) completed web-based interviews. The admission rate to our residency program was not significantly different between applicants completing face-to-face versus web-based interviews. One hundred eleven applicants completed post-interview surveys. The most common reasons for selecting web-based interviews were conflict of interview dates between programs, travel concerns, or financial limitations. Applicants selected face-to-face interviews due to a desire to interact with current residents, or geographic proximity to the residency program.ConclusionsThese results suggest that completion of web-based interviews is a viable alternative to completion of face-to-face interviews, and that choice of interview type does not affect the rate of applicant admission to the residency program. Web-based interviews may be of particular interest to applicants applying to a large number of programs, or with financial limitations
Evolution of squeezed states under the Fock-Darwin Hamiltonian
We develop a complete analytical description of the time evolution of
squeezed states of a charged particle under the Fock-Darwin Hamiltonian and a
time-dependent electric field. This result generalises a relation obtained by
Infeld and Pleba\'nski for states of the one-dimensional harmonic oscillator.
We relate the evolution of a state-vector subjected to squeezing to that of
state which is not subjected to squeezing and for which the time-evolution
under the simple harmonic oscillator dynamics is known (e.g. an eigenstate of
the Hamiltonian). A corresponding relation is also established for the Wigner
functions of the states, in view of their utility in the analysis of cold-ion
experiments. In an appendix, we compute the response functions of the FD
Hamiltonian to an external electric field, using the same techniques as in the
main text
Equivariant differential characters and symplectic reduction
We describe equivariant differential characters (classifying equivariant
circle bundles with connections), their prequantization, and reduction
f-Oscillators and Nonlinear Coherent States
The notion of f-oscillators generalizing q-oscillators is introduced. For
classical and quantum cases, an interpretation of the f-oscillator is provided
as corresponding to a special nonlinearity of vibration for which the frequency
of oscillation depends on the energy. The f-coherent states (nonlinear coherent
states) generalizing q-coherent states are constructed. Applied to quantum
optics, photon distribution function, photon number means, and dispersions are
calculated for the f-coherent states as well as the Wigner function and
Q-function. As an example, it is shown how this nonlinearity may affect the
Planck distribution formula.Comment: Latex, 32 pages, accepted by Physica Script
Coherent states and related quantizations for unbounded motions
We build coherent states (CS) for unbounded motions along two different
procedures. In the first one we adapt the Malkin-Manko construction for
quadratic Hamiltonians to the motion of a particle in a linear potential. A
generalization to arbitrary potentials is discussed. The second one extends to
continuous spectrum previous constructions of action-angle coherent states in
view of a consistent energy quantization
Time-Dependent Invariants for Dirac Equation and Newton-Wigner Position Operator
For Dirac equation, operator-invariants containing explicit time-dependence
in parallel to known time-dependent invariants of nonrelativistic Schr\"odinger
equation are introduced and discussed. As an example, a free Dirac particle is
considered and new invariants are constructed for it. The integral of motion,
which is initial Newton-Wigner position operator, is obtained explicitly for a
free Dirac particle. For such particle with kick modeled by delta-function of
time, the time-depending integral, which has physical meaning of initial
momentum, is found.Comment: LATEX,21 pages,submitted to Physica Script
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