Nonresonant interaction of ultrashort electromagnetic pulses with multilevel quantum systems

Some features of the excitation of multilevel quantum systems under the action of electromagnetic pulses which are shorter than the inverse frequency of interlevel transitions are considered. It is shown that the interaction is characterized by a specific type of selectivity which is not connected with the resonant absorption of radiation. The simplest three-level model displays the inverse population of upper levels. The effect of an ultrashort laser pulse on a multilevel molecule was regarded as an instant reception of the oscillation velocity by the oscillator and this approach showed an effective excitation and dissociation of the molecule. The estimations testify to the fact that these effects can be observed using modern femtosecond lasers

Coherent control using adaptive learning algorithms

We have constructed an automated learning apparatus to control quantum systems. By directing intense shaped ultrafast laser pulses into a variety of samples and using a measurement of the system as a feedback signal, we are able to reshape the laser pulses to direct the system into a desired state. The feedback signal is the input to an adaptive learning algorithm. This algorithm programs a computer-controlled, acousto-optic modulator pulse shaper. The learning algorithm generates new shaped laser pulses based on the success of previous pulses in achieving a predetermined goal.Comment: 19 pages (including 14 figures), REVTeX 3.1, updated conten

Multiorder coherent Raman scattering of a quantum probe field

We study the multiorder coherent Raman scattering of a quantum probe field in a far-off-resonance medium with a prepared coherence. Under the conditions of negligible dispersion and limited bandwidth, we derive a Bessel-function solution for the sideband field operators. We analytically and numerically calculate various quantum statistical characteristics of the sideband fields. We show that the multiorder coherent Raman process can replicate the statistical properties of a single-mode quantum probe field into a broad comb of generated Raman sidebands. We also study the mixing and modulation of photon statistical properties in the case of two-mode input. We show that the prepared Raman coherence and the medium length can be used as control parameters to switch a sideband field from one type of photon statistics to another type, or from a non-squeezed state to a squeezed state and vice versa.Comment: 12 pages, 7 figures, to be published in Phys. Rev.

STRUCTURAL PHASE STATE OF HEAT-RESISTANT CAST INTERMETALLID NICKEL-BASED ALLOYS DEPENDING ON THE THERMAL TREATMENT MODES

Доклад отражает экспериментальные исследования режимов термической обработки (ТО) монокристаллических заготовок с кристаллографической ориентацией (КГО) [111] литейных ренийсодержащих интерметаллидных никелевых сплавов нового поколения серии ВИН после термической обработки (ТО). Показано, что обработка при температурах Tпр– —°С - —°С повлияла на структурно-фазовое состояние и работоспособность исследуемых сплавов.The report reflects the experimental investigations of the thermal treatment regimes of single-crystal bars with crystallographic orientation (CGO) [111] foundry rhenium-containing intermetallic nickel alloys of the new generation of VIN series after heat treatment. It has been established that the treatment at temperatures close to Tsolv– —°С - —°С affected the structural-phase state and the operability of the alloys under study.Работа выполнена при поддержке гранта РФФИ № 16-38-00260 «Исследование закономерностей формирования структурно-фазового состояния жаропрочных литейных интерметаллидных сплавов на основе никеля после различных режимов термической обработки». Авторы выражают глубокую благодарность соавтору сплавов ВИН1 и ВИН4 О. А. Базылевой, канд. техн. наук, зам. начальника по науке лаборатории «Жаропрочные сплавы на основе никеля» ФГУП «ВИАМ»

PhD TUTORIAL: Using feedback for coherent control of quantum systems

A longstanding goal in chemical physics has been the control of atoms and molecules using coherent light fields. This paper provides a brief overview of the field and discusses experiments that use a programmable pulse shaper to control the quantum state of electronic wavepackets in Rydberg atoms and electronic and nuclear dynamics in molecular liquids. The shape of Rydberg wavepackets was controlled by using tailored ultrafast pulses to excite a beam of caesium atoms. The quantum state of these atoms was measured using holographic techniques borrowed from optics. The experiments with molecular liquids involved the construction of an automated learning machine. A genetic algorithm directed the choice of shaped pulses which interacted with the molecular system inside a learning control loop. Analysis of successful pulse shapes that were found by using the genetic algorithm yield insight into the systems being controlled.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48860/2/ob23r1.pd