Piotr Marecki

Application of quantum inequalities to quantum optics

We establish a connection between quantum inequalities, known from quantum-field theory on curved spacetimes, and the degree of squeezing in quantum-optical experiments. We prove an inequality which binds the reduction of the electric-field fluctuations to their duration. The bigger the level of fluctuation suppression the shorter its duration. As an example of an application of this inequality is the case of squeezed light whose phase is controlled with 1% accuracy for which we derive a limit of -15 dB on the allowed degree of squeezing.

Propagation of sound on line vortices in superfluids: role of ergoregions

We (re)consider the propagation of small disturbances (sound waves) in the presence of an irrotational vortex in a superfluid pinned/wound on a stiff central wire, with the help of the formalism of acoustic spacetimes. We give closed formulas for the scattering angle for sound rays, formulate the sound-propagation problem in the Hamiltonian form and discuss the form of boundary conditions at the core of the vortex, where the Hamiltonian has a singular point. The wave equation is simplified to a single ordinary differential equation of Mathieu type. We give an extensive discussion of perturbations localized close to the core, which are similar to what is known as the Kelvin waves for vortices that are bendable (not pinned). The spectra of modes depend strongly on the type of boundary condition employed close to the vortex core. The gapless mode with the angular number ?1, the Kelvin mode usually discussed in the context of unpinned vortices in superfluid helium or rotating Bose?Einstein condensates, turns out either not to exist or to have a completely different dispersion relation if the vortex is pinned. The question of whether or not the acoustic spacetime admits an ergoregion turns out to have a decisive (qualitative) influence on many aspects of sound-propagation phenomena.

Bounds on the energy densities of ground states on static spacetimes of compact objects

This paper deals with energy densities of scalar, massless quantum fields propagating on given, static, spherically symmetric, horizon-free spacetimes, such as these of spherical stars. The outer part of the spacetimes is assumed to be described by Schwarzschild metric, while the inner, matter containing part, which begins at the distance

ON QUANTUM EFFECTS IN THE VICINITY OF WOULD-BE HORIZONS

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Spontaneous emission of light from atoms: the model

from the horizon of the Schwarzschild spacetime (measured along the spacelike radial geodesic on the surface of constant time on the Schwarzschild spacetime) is left unspecified. We shall put bounds on the ground-state expectation values of locally constructed (that is: by point-splitting and subtraction of the Hadamard singular part) energy-density operators

Balanced homodyne detectors in quantum field theory

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Balanced homodyne detectors and Casimir energy densities

, localized in the outer region. These bounds, which are derived from the so-called quantum energy inequalities, limit in absolute the difference between the energy density of ground states and the energy density of the Boulware state (the ground state for Schwarzschild spacetime). The sharpness of the bound from below depends critically on the distance

Quantum Electrodynamics on background external fields

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A vortex model for rotating compact objects

, but not on the details of internal geometry of the objects. In the limit of small

Rotating De Sitter Space

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