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

Numerical methods for computing Casimir interactions

We review several different approaches for computing Casimir forces and related fluctuation-induced interactions between bodies of arbitrary shapes and materials. The relationships between this problem and well known computational techniques from classical electromagnetism are emphasized. We also review the basic principles of standard computational methods, categorizing them according to three criteria---choice of problem, basis, and solution technique---that can be used to classify proposals for the Casimir problem as well. In this way, mature classical methods can be exploited to model Casimir physics, with a few important modifications.Comment: 46 pages, 142 references, 5 figures. To appear in upcoming Lecture Notes in Physics book on Casimir Physic

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

Reconsidering the quantization of electrodynamics with boundary conditions and some measurable consequences

We show that the commonly known conductor boundary conditions $E_{||}=B_\perp=0$ 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 $E_\perp$ of the electric field whereas for a 'thin' conductor $E_\perp$ 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