Search results for "Diabatic"
showing 10 items of 303 documents
Ultrafast stimulated Raman parallel adiabatic passage by shaped pulses
2009
We present a general and versatile technique of population transfer based on {\it parallel adiabatic passage} by femtosecond shaped pulses. Their amplitude and phase are specifically designed to optimize the adiabatic passage corresponding to parallel eigenvalues at all times. We show that this technique allows the robust adiabatic population transfer in a Raman system with the total pulse area as low as 3 $\pi$, corresponding to a fluence of one order of magnitude below the conventional stimulated Raman adiabatic passage process. This process of short duration, typically pico- and subpicosecond, is easily implementable with the modern pulse shaper technology and opens the possibility of ul…
Influence of Unequal Oscillator Strenghts on Stimulated Raman Adiabatic Passage through Bright State
2011
The problem of the coherent control of atomic states, preparation of atoms in a stable superposition state, and atomic population transfer has attracted much attention in the last decade. One of the main motivations is associated with the rapid development of the field of quantum computing. One of the key problems of quantum information processing is the construction of given coherent superposition atomic states in a macroscopic volume. Stimulated Raman adiabatic passage (STIRAP) [1] is considered to be the most common method for atomic population transfer in quantum systems. Being analyzed in detail on various quantum systems from both theoretical and experimental points of view, this meth…
Population transfer and superluminal propagation by bright‐state adiabatic passage.
2008
Transition dynamics in optical fiber amplifiers operating in the normal dispersion regime
2011
Over the past decade there has been large interest in ultrafast optical fiber amplifiers operating in the normal dispersion regime because of the discovery that, high-energy pulses with a parabolic intensity profile and linear frequency chirp are the asymptotic solution to the system for arbitrary initial conditions [1]. These so-called “similariton” solutions propagate in a self-similar manner, holding certain relations (scaling) between pulse power, duration, and chirp parameter. While the asymptotic similariton features seem now well understood [1], the physics of the transition to this solution from arbitrary initial pulses has not been fully explored yet (most of the previous attempts …
Orientation of Polar Molecules by Laser Induced Adiabatic Passage
2002
International audience; We show that two overlapping linearly polarized laser pulses of frequencies ω and its second harmonic 2ω can strongly orient linear polar molecules, by adiabatic passage along dressed states. The resulting robust orientation can be interpreted as a laser-induced localization in the effective double well potential created by the fields, which induces a preliminary molecular alignment. The direction of the orientation can be selected by the relative phase of the fields.
Optimal control and shortcuts to adiabaticity techniques in linear and non-linear systems : from ion cyclotron resonance to nuclear magnetic resonance
2021
The goal of our research is to develop efficient and robust control protocols for classical and quantum systems. To this end, we have applied optimal control theory (OCT) and shortcuts to adiabaticity (STA) with inverse engineering and motion planning approaches in three different examples, which are RC (Resistor Capacitor) circuits, Fourier Transform-Ion Cyclotron Resonance (FT-ICR), and Nuclear Magnetic Resonance (NMR). Some of our results are not limited to these systems but are rather general. We apply OCT and STA with an inverse engineering approach to control the time-evolution of the charge on a capacitor. We show that OCT is a member of the family of STA solutions. In order to contr…
The Kleiner Feldberg Cloud Experiment 1990. An overview
1994
An overview is given of the Kleiner Feldberg cloud experiment performed from 27 October until 13 November 1990. The experiment was carried out by numerous European research groups as a joint effort within the EUROTRAC-GCE project in order to study the interaction of cloud droplets with atmospheric trace constituents. After a description of the observational site and the measurements which were performed, the general cloud formation mechanisms encountered during the experiment are discussed. Special attention is given here to the process of moist adiabatic lifting. Furthermore, an overview is given regarding the pollutant levels in the gas phase, the particulate and the liquid phase, and som…
On the electron affinity of TCNQ
2004
The electron affinity of 7,7,8,8-tetracyano-p-quinodimethane (TCNQ) has been studied with density functional theory and coupled cluster (CC) procedures. The adiabatic electron affinity of TCNQ calculated with the B3LYP method is about 1 eV higher than the available experimental value. At the CCSD(T) level, the theoretical result is overestimated by more than 0.4 eV. The electron affinity computed for TCNQ is larger than that obtained for tetracyanoethylene at all levels of calculation, exactly the opposite of what is observed experimentally. Accordingly, a call for an additional empirical measurement of such a property is made.
Identifying Vibrations that Control Non-adiabatic Relaxation of Polaritons in Strongly Coupled Molecule-Cavity Systems
2022
The strong light–matter coupling regime, in which excitations of materials hybridize with excitations of confined light modes into polaritons, holds great promise in various areas of science and technology. A key aspect for all applications of polaritonic chemistry is the relaxation into the lower polaritonic states. Polariton relaxation is speculated to involve two separate processes: vibrationally assisted scattering (VAS) and radiative pumping (RP), but the driving forces underlying these two mechanisms are not fully understood. To provide mechanistic insights, we performed multiscale molecular dynamics simulations of tetracene molecules strongly coupled to the confined light modes of an…
Non-adiabatic vacuum induced berry phase
2016
We investigate quantum effects in geometric phases arising when a two-level system is interacting with a quantized electromagnetic field.