The Localized Quantum Vacuum Field

A model for the localized quantum vacuum is proposed in which the zero-point energy of the quantum electromagnetic field originates in energy- and momentum-conserving transitions of material systems from their ground state to an unstable state with negative energy. These transitions are accompanied by emissions and re-absorptions of real photons, which generate a localized quantum vacuum in the neighborhood of material systems. The model could help resolve the cosmological paradox associated to the zero-point energy of electromagnetic fields, while reclaiming quantum effects associated with quantum vacuum such as the Casimir effect and the Lamb shift; it also offers a new insight into the Zitterbewegung of material particles.Comment: 21 pages, 1 figur

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

Causality-based criteria for a negative refractive index must be used with care

Using the principle of causality as expressed in the Kramers-Kronig relations, we derive a generalized criterion for a negative refractive index that admits imperfect transparency at an observation frequency $\omega$. It also allows us to relate the global properties of the loss (i.e. its frequency response) to its local behaviour at $\omega$. However, causality-based criteria rely the on the group velocity, not the Poynting vector. Since the two are not equivalent, we provide some simple examples to compare the two criteria.Comment: slightly longer version of published PR

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

No anomalous scaling in electrostatic calibrations for Casimir force measurements

In a recent paper (Phys.Rev.A78, 020101(R) (2008)), Kim at al. have reported a large anomaly in the scaling law of the electrostatic interaction between a sphere and a plate, which was observed during the calibration of their Casimir force set-up. Here we experimentally demonstrate that in proper electrostatic calibrations the scaling law follows the behavior expected from elementary electrostatic arguments, even when the electrostatic voltage that one must apply to minimize the force (typically ascribed to contact potentials) depends on the separation between the surfaces.Comment: Final versio