arXiv subjects

H. L. Haroutyunyan

Publications and source records attributed to H. L. Haroutyunyan.

6 recordsLinked to original sources

arXiv2004

Coherent control of atom dynamics in an optical lattice

On the basis of a simple exactly solvable model we discuss the possibilities for state preparation and state control of atoms in a periodic optical potential. In addition to the periodic potential a uniform force with an arbitrary time dependence is applied. The method is based on a formal expression for the full evolution operator in the tight-binding limit. This allows us to describe the dynamics in terms of operator algebra, rather than in analytical expansions.

physics.atom-ph↗

arXiv2004

Resonances for coupled Bose-Einstein Condensates

We study some effects arising from periodic modulation of the asymmetry and the barrier height of a two-well potential containing a Bose-Einstein condensate. At certain modulation frequencies the system exhibits resonances, which may lead to enhancement of the tunneling rate between the wells and which can be used to control the particle distribution among the wells. Some of the effects predicted for a two-well system can be carried over to the case of a Bose-Einstein condensate in an optical lattice.

quant-ph↗

arXiv2004

Diffraction and trapping in circular lattices

When a single two-level atom interacts with a pair of Laguerre-Gaussian beams with opposite helicity, this leads to an efficient exchange of angular momentum between the light field and the atom. When the radial motion is trapped by an additional potential, the wave function of a single localized atom can be split into components that rotate in opposite direction. This suggests a novel scheme for atom interferometry without mirror pulses. Also atoms in this configuration can be bound into a circular lattice.

quant-ph↗

arXiv2003

Phase dynamics of a multimode Bose condensate controlled by decay

The relative phase between two uncoupled BE condensates tends to attain a specific value when the phase is measured. This can be done by observing their decay products in interference. We discuss exactly solvable models for this process in cases where competing observation channels drive the phases to different sets of values. We treat the case of two modes which both emit into the input ports of two beam splitters, and of a linear or circular chain of modes. In these latter cases, the transitivity of relative phase becomes an issue.

quant-ph↗

arXiv2002

Analogy between a two-well Bose-Einstein condensate and atom diffraction

We compare the dynamics of a Bose-Einstein condensate in two coupled potential wells with atoms diffracting from a standing light wave. The corresponding Hamiltonians have an identical appearance, but with a different set of commutation rules. Well-known diffraction phenomena as Pendellosung oscillations between opposite momenta in the case of Bragg diffraction, and adiabatic transitions between momentum states are shown to have analogies in the two-well case. They represent the collective exchange of a fixed number of atoms between the wells.

physics.atom-ph↗

arXiv1999

Large Scale (Multiphoton) Evolution of Atomic Energy Level's Mean Momentum for Single-Photon Absorption/Emission Process

It is shown that a two-level atom, being initially in general superposition state of ground and excited energy levels with mutually different momentum distributions there, gets a large scale evolution in the energy levels momentum distribution. As a consequence the mean momentum of each individual energy level also gets large scale changes, more than the own momentum hbar k of the photon. Because of not completeness of the literature under the hand, we are not sure that this simple phenomenon isn't known in quantum theory of atom-photon interactions or, particularly, in the interferometry of atomic matter waves. One of main purposes of this article is our request to the leading specialists to respond and if the phenomenon is known, send the corresponding references. Thoroughly is discussed the special case, when the atom's preliminary superposition state is created as a result of interaction of the atom with the resonant standing wave. Also it is pointed that in such conditions the mentioned phenomenon can be presented as a transformation of the resonant Kapitza-Dirac splitting of atomic states into the Stern-Gerlach type splitting.

physics.atom-ph↗