We study spontaneous parametric down-conversion generating ultra-broadband biphotons in spatially chirped photoniclike crystals. The novelty is that these structures are considered as definite assembles of second-order layers with both linear and nonlinear chirping. It is shown that the biphoton spectra for two structures with linear and nonlinear chirps under consideration are essentially different in form.
We discuss formation of two-dimensional spatial structures of atoms due to atomic diffraction on two crossed standing electromagnetic fields. This analysis proposed for V-type atomic configuration under dispersive atom-field interactions in quantum regime. Localization of the position of atoms passing through standing light wave is initiated by making a quadrature phase measurement on the light fields. We develop the procedure for strong two-dimensional spatial localization of atomic beam within the optical wavelength. Considering atomic spatial localization in the presence of entanglement of two light beams various two-dimensional patterns for V-type atoms are reported.
We investigate quasi-phase-matching (QPM) and spontaneous parametric down-conversion in randomly poled structures. The novelty is that we consider the disordered structure which involves nonlinear segments separated by domains with linear optical spacers of random lengths. Considering down-conversion, we calculate the probability of production of pair photons by using the procedure of averaging over random positions of domains boundaries. We demonstrate the method of compensation of the dispersive effects in nonlinear segments by appropriately chosen linear dispersive segments of superlattice for realizing effective QPM and preparation of joint states of two photons.
We investigate production of three-photon states in cascaded parametric down-conversion (PDC). The analysis includes preparation of Greenberger-Horne-Zeilinger polarization-entangled states in cascaded type-II and type-I PDC in the framework of considering the dual-grid structure that involves two periodically poled crystals. Considering cascaded optical parametric oscillator (OPO) driven by a sequence of laser pulses with Gaussian time-dependent envelopes, we investigate quantum statistical properties of high intensity mode generated in intracavity three-photon splitting. Calculating the normalized third-order correlation function below-and at the generation threshold, we demonstrate that in the pulsed regime, depending on the duration of pulses and the time-interval separations between them, the degree of three-photon-number correlation essentially exceed the analogous one for the case of continuous pumping.
Recently, superconducting artificial atom has been justified experimentally as an ideal element for various
applications including circuit quantum electrodynamics realizing strong-coupling limit. Some of the proposed
systems in this area are usually described in terms of the quantum anharmonic oscillator and display quantum
dynamics in macroscopic level, giant nonlinearity as well as very strong coupling with external field and strong
coupling with an environment. In this report, we investigate the quantum properties of an artificial atom as a
model of multilevel anharmonic oscillator in the framework of photon number distributions as well as the Wigner
functions. We concentrate on the regimes of strong driving and giant nonlinearity that allow us to consider
artificial atom on the level of few excitation numbers.
Deflection of an atomic beam passing through two crossed standing light waves is proposed for studies of transition
through the Raman resonance in Λ -atomic systems. Considering different regimes of excitation of Λ -atoms by offresonant
standing waves, we demonstrate that the deflection patterns, in the plane perpendicular to the direction of the
center of atomic mass motion, are essentially different for the cases of one-photon and two-photon excitations.
Visualization of the quantum superposition states of low atomic levels on the two-dimensional spatial patterns of atomic
deflection is performed.
We investigate production of three-photon and four-photon states in cascaded parametric processes of photon splitting
and summing in χ (2)nonlinear media, under action of pump field. Generation of photon triplets using simultaneously phase
matched three-photon processes: ω0↔ω1+ω2 , ω2↔ω1+ω1 , is considered in dual-grating layered structure that involves
nonlinear and linear segments. The production of heralded two-photon entangled states from three-photon states is analyzed
for this configuration by using the method of conditional detection of auxiliary photons. Cascaded four-photon downconversion
based on simultaneously phase matched three-photon processes: ω0↔ω2 +ω2 , ω2↔ω1+ω1 is arranged for
phase-reversed configuration. The effects of correlation between photons in both three-photon and four-photon states is
analyzed in the regimes of amplification of corresponding modes at the frequency of three-photon downconversion
ω1 = ω0/3 and the frequency of four-photon down-conversion ω1 = ω0/4respectively for both cascaded systems.
We investigate specific features of the dispersive vacuum polarization effects for the light propagation in magnetized
vacuum which are induced due to spatial modulation of the magnetic field. The reciprocal lattice vectors associated with
the periodic field are involved in the energy-momentum conservation for the photon interaction processes which allow
elastic scattering of impinging photons by a strong magnetic field. The efficiency of the scattering is shown to be
coherently enhanced due to interference of the scattered waves from the periodic structure.
We propose and analyze a scheme for creation of coherent superposition of meta-stable states in a multilevel
atom. The scheme is based on interaction of a frequency modulated (chirped) laser pulse and a pulse of a
constant carrier frequency with the atom having two meta-stable (ground) states and multiple excited states. The
negligible excitation of the atoms is a priority in the proposed scheme to eliminate the de-coherence processes
caused by the decay of the excited states. The scheme is applied to create coherent superposition of magnetic
sublevels of ground states of the 87Rb atom taking into account all allowed electric-dipole transitions between
magnetic sublevels of the 5 2S1/2
- 52P3/2 transition (D2 line).
In addition to the theoretical analysis we consider possible experimental realizations of the proposed
coherence creation scheme and discuss their feasibilities and constraints. We concentrate on a detection of the
superposition state in the Faraday-rotation experiment. Such detection reduces technical laser noise background
and offers high sensitivity of the coherence detection. Moreover, it allows extra control of the atomic sample and
the interaction dynamics by external magnetic field.
We investigate time-modulation of continuous variable (CV) quantum states of light fields in application to time-resolved quantum communications. As realizations, we consider EPR entangled states of light as well as correlated twin beams generated in nondegenerate optical parametric oscillator (NOPO) subjected by a sequence of laser pulses. We demonstrate that time-modulation of a pump field essentially improves the degrees of both cv entanglement and intensity quantum correlation in NOPO doing them beyond the standard limits.
The resonance fluorescence of a harmonically trapped two- level ion is investigated including effects, which result from the quantized motion. The interaction of a cold trapped ion with a strong laser field is studied in two configurations in which dressed states structure become important, but heating of the ion is unessential.
We investigate the marriage of two different optical nonlinearities, which allow us to control the operation regimes of an intracavity light generation. Two kinds of cascaded nonlinear optical schemes involved two- and three- Hopf bifurcations are presented.
We investigate the conquest of sideband laser cooling and heating due to weak broad-band noise for a harmonically trapped two-level ion. The two opposite processes from an equilibrium distribution in the ion's quantum state of motion, i.e., the ground state of motion is depopulated. As another consequence we find population inversion between different manifolds of the ion's combined quantum states of internal electronic structure and external motion. This effect only results from the quantized treatment of the ion's motion.