Vlasta Peřinová

Principal squeezing of vacuum fluctuations

Abstract With regard to the squeezing detection process a more substantial definition of squeezing is proposed based on the sharpened Heisenberg uncertainty inequality. This notion involves the quadrature correlation and is rotationally invariant.

Quantum statistics of four-wave mixing

Abstract Photon statistics in four-wave mixing are discussed, with particular attention to antibunching of photons, their subpoissonian behaviour and to squeezing, making use of the short-length approximation or the parametric approximation. All possibilities are found to generate these non-classical optical fields with the use of four-wave mixing and the obtained results are compared with those for optical parametric processes and non-degenerate hyper-Raman scattering.

Quantum aspects of light propagation

Origin of Macroscopic Approach.- Macroscopic Theories and Their Applications.- Microscopic Theories.- Microscopic Models as Related to Macroscopic Descriptions.- Periodic and Disordered Media.- Conclusions.

Photon Statistics of Non-classical Fields

The photon statistics of radiation of a damped harmonic oscillator with an initial squeezed state are investigated. It is shown that a generalized model of the superposition of coherent and chaotic fields involving possibly negative noise is appropriate in this case. The influence of quantum damping can easily be recognized in this process. A relationship between sub-Poissonian statistics and squeezing is thoroughly discussed. A degenerate parametric process is related to the investigated model.

Quantum statistics of light in a lossless linear coupler

Abstract The quantum description of light transferred by lossless linear directional and contradirectional couplers is given. The periodical and non-periodical switchings of light and its properties between modes are presented in the dependence on the coupling constant and the detuning for the generalized superpositions of coherent and chaotic fields at the inputs.

State Reduction for Correlated Photons and Eigenstates of Unitarily and Non-unitarily Displaced Number Operator

Abstract The number-quadrature minimum-uncertainty states after rotation and displacement emerge in the parametric down-conversion followed by photon number measurement in the idler mode when the coherent state inputs. Again, the state generated in the signal mode by the reduction is described by the principally measurable quantum-statistical tools.

Quantum correlation and entanglement between an ionizing system and a neighboring atom interacting directly and via a quantized field

Quantum correlations between two neighbor atoms are studied. It is assumed that one atomic system comprises a single auto-ionizing level and the other atom does not contain any auto-ionizing level. The excitation of both atoms is achieved by the interaction with the same mode of the quantized field. It is shown that the long-time behavior of two atoms exhibits quantum correlations even when the atoms do not interact directly. This can be shown using the optical excitation of the neighbor atom. Also a measure of entanglement of two atoms can be applied after reduction of the continuum to two levels.

Fano zeros in photoelectron spectra of an autoionization system interacting with a neighboring atom.

Photoelectron ionization spectra of an autoionization system interacting with a neighboring two-level atom are studied using the method of canonical transformation. Conditions for the occurrence of a Fano zero are exactly derived, together with its frequency. Ionization spectra are typically composed of at most four peaks in this case. Sharp peaks occur not far from the Fano zero due to the confluence of bound-free coherences. Spectral peaks close to the Fano zero are suppressed. Also dynamical zeros appearing once per the Rabi period in conditioned photoelectron ionization spectra are observed.

Dynamics of nonclassical properties of two- and four-mode Bose–Einstein condensates

A two-mode Bose–Einstein condensate (BEC) prepared in a Fock state initially evolves due to the coupling of modes. The time evolution of nonclassical properties exhibits that inter-mode entanglement, single-mode and higher order antibunching are present. A four-mode BEC is considered with the initial minimum-energy Bloch states, and the nonclassical behaviour is confirmed.

Linear coupling, loss and gain of counterpropagating beams

We investigate counterpropagation of the two-mode input state in a corrugated waveguide, which reproduces a photonic band-gap structure. First assuming a gain medium, we model a distributed feedback laser as an amplifier. From this case we pass to the attenuator, which corresponds to a lossy medium. We determine the transmission and fidelity spectra for the waveguide in the dependence on a mismatch coefficient and a measure of losses.