48 research outputs found
Free Energy of Coupled Oscillators: Lamb Shifts and van der Waals Interactions
The Helmholtz free energy of oscillators in thermal equilibrium with
electromagnetic radiation is obtained from the Pauli-Hellmann-Feynman theorem
and applied to some aspects of Lamb shifts and van der Waals interactions.Comment: This article belongs to the special issue of Acta Physica Polonica A
printed in honor of Professor Iwo Bialynicki-Birula on the occasion of his
90th birthday (Ed. Tomasz Sowinski, DOI:10.12693/APhysPolA.143.S0
Improving the sensitivity of FM spectroscopy using nano-mechanical cantilevers
It is suggested that nano-mechanical cantilevers can be employed as high-Q
filters to circumvent laser noise limitations on the sensitivity of frequency
modulation spectroscopy. In this approach a cantilever is actuated by the
radiation pressure of the amplitude modulated light that emerges from an
absorber. Numerical estimates indicate that laser intensity noise will not
prevent a cantilever from operating in the thermal noise limit, where the high
Q's of cantilevers are most advantageous.Comment: 5 pages, 1 figur
Recommended from our members
Quantum optics mini-program on fast light, slow light, and metamaterials.
The topic of electromagnetic propagation in dielectric media has been enlivened in the past decade by a number of remarkable experimental results showing the technical ability to control the speed of light propagation in exotic ways. Light pulses have been observed travelling faster than c, or slowed by many orders of magnitude, or even stopped completely. All of thcse results require careful interpretation, and a variety of theoretical interpretations have been proposed and/or published, not all agreeing with each other. At the same time, in a lower frequency range than optical, rapid development of so-called meta-materials or double-negative materials has occurred. These materials are characterized by electric permittivity and magnetic permeability with very unconventional values, both quantities negative in some cases. Such unusual properties, especially when leading to a negative value for the group velocity, clearly indicate another possibility for control of light. Such materials are being improved rapidly, but independent of their implementation in the laboratory, their theoretical properties have led to dramatic predictions such as the existence of a perfect lens, Le., a finite lens (actually even planar-flat rather than parabolic) that can deliver an ideally sharp focus unaffected by diffractive effects. There are strong contentions currently being published that such predictions are erroneou
Complementarity and uncertainty relations for matter wave interferometry
We establish a rigorous quantitative connection between (i) the
interferometric duality relation for which-way information and fringe
visibility and (ii) Heisenberg's uncertainty relation for position and modular
momentum. We apply our theory to atom interferometry, wherein spontaneously
emitted photons provide which way information, and unambiguously resolve the
challenge posed by the metamaterial `perfect lens' to complementarity and to
the Heisenberg-Bohr interpretation of the Heisenberg microscope thought
experiment.Comment: nine pages, five figure
Electromagnetic Momentum in Dispersive Dielectric Media
When the effects of dispersion are included, neither the Abraham nor the
Minkowski expression for electromagnetic momentum in a dielectric medium gives
the correct recoil momentum for absorbers or emitters of radiation. The total
momentum density associated with a field in a dielectric medium has three
contributions: (i) the Abraham momentum density of the field, (ii) the momentum
density associated with the Abraham force, and (iii) a momentum density arising
from the dispersive part of the response of the medium to the field, the latter
having a form evidently first derived by D.F. Nelson [Phys. Rev. A 44, 3985
(1991)]. All three contributions are required for momentum conservation in the
recoil of an absorber or emitter in a dielectric medium. We consider the
momentum exchanged and the force on a polarizable particle (e.g., an atom or a
small dielectric sphere) in a host dielectric when a pulse of light is incident
upon it, including the dispersion of the dielectric medium as well as a
dispersive component in the response of the particle to the field. The force
can be greatly increased in slow-light dielectric media.Comment: 9 pages. To be published by Optics Communication
Effect of quantum and thermal jitter on the feasibility of Bekenstein’s proposed experiment to search for Planck-scale signals
A proposed experiment to test whether space is discretized [J. D. Bekenstein, Phys. Rev. D 86, 124040 (2012); Found. Phys. 44, 452 (2014)] is based on the supposed impossibility of an incident photon causing a displacement of a transparent block by less than the Planck length. An analysis of the quantum and thermal jitter of the block shows that it greatly diminishes the possibility that the experiment could reveal Planck-scale signals
Atomic states in optical traps near a planar surface
In this work we discuss the atomic states in a vertical optical lattice in
proximity of a surface. We study the modifications to the ordinary
Wannier-Stark states in presence of a surface and we characterize the energy
shifts produced by the Casimir-Polder interaction between atom and mirror. In
this context, we introduce an effective model describing the finite size of the
atom in order to regularize the energy corrections. In addition, the
modifications to the energy levels due to a hypothetical non-Newtonian
gravitational potential as well as their experimental observability are
investigated.Comment: 12 pages, 8 figure
Reconsidering the quantization of electrodynamics with boundary conditions and some measurable consequences
We show that the commonly known conductor boundary conditions
can be realized in two ways which we call 'thick' and 'thin'
conductor. The 'thick' conductor is the commonly known approach and includes a
Neumann condition on the normal component of the electric field
whereas for a 'thin' conductor remains without boundary condition.
Both types describe different physics already on the classical level where a
'thin' conductor allows for an interaction between the normal components of
currents on both sides. On quantum level different forces between a conductor
and a single electron or a neutral atom result. For instance, the
Casimir-Polder force for a 'thin' conductor is by about 13% smaller than for a
'thick' one.Comment: 22 pages, basic statement weakened, conclusions changed, misprints
correcte