308 research outputs found
Time-minimal control of dissipative two-level quantum systems: The Integrable case
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.Comment: 24 pages, 6 figure
Time-Minimal Control of Dissipative Two-level Quantum Systems: the Generic Case
The objective of this article is to complete preliminary results concerning
the time-minimal control of dissipative two-level quantum systems whose
dynamics is governed by Lindblad equations. The extremal system is described by
a 3D-Hamiltonian depending upon three parameters. We combine geometric
techniques with numerical simulations to deduce the optimal solutions.Comment: 24 pages, 16 figures. submitted to IEEE transactions on automatic
contro
Newton algorithm for Hamiltonian characterization in quantum control
We propose a Newton algorithm to characterize the Hamiltonian of a quantum
system interacting with a given laser field. The algorithm is based on the
assumption that the evolution operator of the system is perfectly known at a
fixed time. The computational scheme uses the Crank-Nicholson approximation to
explicitly determine the derivatives of the propagator with respect to the
Hamiltonians of the system. In order to globalize this algorithm, we use a
continuation method that improves its convergence properties. This technique is
applied to a two-level quantum system and to a molecular one with a double-well
potential. The numerical tests show that accurate estimates of the unknown
parameters are obtained in some cases. We discuss the numerical limits of the
algorithm in terms of basin of convergence and non uniqueness of the solution.Comment: 18 pages, 7 figure
Field-free molecular orientation by THz laser pulses at high temperature
We investigate to which extend a THz laser pulse can be used to produce
field-free molecular orientation at high temperature. We consider laser pulses
that can be implemented with the state of the art technology and we show that
the efficiency of the control scheme crucially depends on the parameters of the
molecule. We analyze the temperature effects on molecular dynamics and we
demonstrate that, for some molecules, a noticeable orientation can be achieved
at high temperature.Comment: 13 pages, 7 figure
Robust quantum control by shaped pulse
Considering the problem of the control of a two-state quantum system by an
external field, we establish a general and versatile method that allows the
derivation of smooth pulses, suitable for ultrafast applications, that feature
the properties of high-fidelity, robustness, and low area. Such shaped pulses
can be viewed as a single-shot generalization of the composite pulse technique
with a time-dependent phase
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