Search results for "Quantum dynamic"
showing 10 items of 129 documents
A quantum dynamics study of the benzopyran ring opening guided by laser pulses
2014
Abstract The ring-opening photoisomerization of benzopyran, which occurs via a photochemical route involving a conical intersection, has been studied with quantum dynamics calculations using the multi-configuration time-dependent Hartree method (MCTDH). We introduce a mechanistic strategy to control the conversion of benzopyran to merocyanine with laser pulses. We use a six-dimensional model developed in a previous work for the potential energy surfaces (PES) based on an extension of the vibronic-coupling Hamiltonian model (diabatization method by ansatz), which depends on the most active degrees of freedom. The main objective of these quantum dynamics simulations is to provide a set of str…
Quantum dynamics of 16O in collision with ortho- and para-17O17O
2017
Abstract We report full quantum dynamical observables, such as integral and differential cross sections and rate constants, for the 16 O + 17 O 17 O reactive collision process. We particularly emphasize the effect coming from the nonzero nuclear spin of 17 O, leading to two nuclear spin isomers of 34 O 2 , ortho- and para- 34 O 2 which can be studied independently and behave differently. A comparison with the 16 O + 18 O 18 O collision is given. We find that processes involving 17 O 17 O are always faster than with 18 O 18 O.
Quantum Dynamics of the 17O + 32O2 Collision Process
2016
We report full quantum integral and differential cross sections and rate constants for the 17O + 32O2 reactive process. This constitutes the first quantum scattering study of the 17O16O16O system. We emphasize the comparison with the 18O + 32O2 collision in close connection to the mass-independent fractionation (hereafter referred to as MIF) puzzle for ozone in atmospheric chemistry. We find similar general trends in the cross sections and rate constants for both rare isotopes, but we note some singular behaviors peculiar to the use of 17O isotope, particularly at the lowest collision energies.
TIME-MINIMAL CONTROL OF DISSIPATIVE TWO-LEVEL QUANTUM SYSTEMS: THE INTEGRABLE CASE
2009
The objective of this article is to apply recent developments in geometric optimal control to analyze the time minimum control problem of dissipative two-level quantum systems whose dynamics is governed by the Lindblad equation. We focus our analysis on the case where the extremal Hamiltonian is integrable.
The Dynamical Problem for a Non Self-adjoint Hamiltonian
2012
After a compact overview of the standard mathematical presentations of the formalism of quantum mechanics using the language of C*- algebras and/or the language of Hilbert spaces we turn attention to the possible use of the language of Krein spaces.I n the context of the so-called three-Hilbert-space scenario involving the so-called PT-symmetric or quasi- Hermitian quantum models a few recent results are reviewed from this point of view, with particular focus on the quantum dynamics in the Schrodinger and Heisenberg representations.
Quantum state engineering using one-dimensional discrete-time quantum walks
2017
Quantum state preparation in high-dimensional systems is an essential requirement for many quantum-technology applications. The engineering of an arbitrary quantum state is, however, typically strongly dependent on the experimental platform chosen for implementation, and a general framework is still missing. Here we show that coined quantum walks on a line, which represent a framework general enough to encompass a variety of different platforms, can be used for quantum state engineering of arbitrary superpositions of the walker's sites. We achieve this goal by identifying a set of conditions that fully characterize the reachable states in the space comprising walker and coin, and providing …
Grid methods and Hilbert space basis for simulations of quantum dynamics
1999
We discuss spatial grid methods adapted to the structure of Hilbert spaces, used to simulate quantum mechanical systems. We review the construction of Finite Basis Representation (FBR) and the Discrete Variable Representation (DVR). A mixed representation (pseudo-spectral method) is constructed through a quadrature relation linking both bases.
(H, ρ)-induced dynamics and the quantum game of life
2017
Abstract We propose an extended version of quantum dynamics for a certain system S , whose evolution is ruled by a Hamiltonian H, its initial conditions, and a suitable set ρ of rules, acting repeatedly on S . The resulting dynamics is not necessarily periodic or quasi-periodic, as one could imagine for conservative systems with a finite number of degrees of freedom. In fact, it may have quite different behaviors depending on the explicit forms of H, ρ as well as on the initial conditions. After a general discussion on this (H, ρ)-induced dynamics, we apply our general ideas to extend the classical game of life, and we analyze several aspects of this extension.
Quantum dynamics of 16O + 36O2 and 18O + 32O2 exchange reactions
2015
We present quantum dynamical investigations of (16)O + (36)O2 and (18)O + (32)O2 exchange reactions using a time-independent quantum mechanical method and an accurate global potential energy surface of ozone [Dawes et al., J. Chem. Phys. 135, 081102 (2011)]. Initial state-selected integral cross sections, rate constants, and Boltzmann averaged thermal rate constants are obtained and compared with earlier experimental and theoretical results. The computed thermal rate constants for the oxygen exchange reactions exhibit a negative temperature dependence, as found experimentally. They are in better agreement with the experiments than the previous studies on the same reactions.
Quantum effects in the dynamics of intensity-dependent two-mode two-photon models of radiation—matter interaction
1996
Abstract We study the two-photon interaction of a two-state localized system with two modes of a quantized electromagnetic or elastic field. Assuming the coupling strength and the atom-field detuning depending on the mode populations, we find that the quantum atomic dynamics manifests nonclassical features related to the specific nonlinear model investigated.