483 research outputs found
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
Time minimal control of batch reactors
Abstract In this article we consider a control system modelling a batch reactor in which three species X
Energy minimization problem in two-level dissipative quantum control: meridian case
International audienceWe analyze the energy-minimizing problem for a two-level dissipative quantum system described by the Kossakowsky-Lindblad equation. According to the Pontryagin Maximum Principle (PMP), minimizers can be selected among normal and abnormal extremals whose dynamics are classified according to the values of the dissipation parameters. Our aim is to improve our previous analysis concerning 2D solutions in the case where the Hamiltonian dynamics are integrable
Quantum Multiobservable Control
We present deterministic algorithms for the simultaneous control of an
arbitrary number of quantum observables. Unlike optimal control approaches
based on cost function optimization, quantum multiobservable tracking control
(MOTC) is capable of tracking predetermined homotopic trajectories to target
expectation values in the space of multiobservables. The convergence of these
algorithms is facilitated by the favorable critical topology of quantum control
landscapes. Fundamental properties of quantum multiobservable control
landscapes that underlie the efficiency of MOTC, including the multiobservable
controllability Gramian, are introduced. The effects of multiple control
objectives on the structure and complexity of optimal fields are examined. With
minor modifications, the techniques described herein can be applied to general
quantum multiobjective control problems.Comment: To appear in Physical Review
Care of newly purchased feeder cattle
"The way cattle are handled shortly before loading, during hauling and the first two weeks in the feedlot has a great influence on the overall performance of feedlot cattle. There is no one program that will give best results for all feeder cattle, nor will the same results occur each year. "Cattle sense" is developed by close observation and experience. Keep records on each bunch of cattle. These records will be useful in helping you provide the most practical and economical program for the next group of incoming cattle. Develop a program which fits your operation and area. Post mortem examinations are worthwhile in ascertaining problems and the results should be considered for future health and management programs. The following are general guidelines which should be helpful to you in deciding how to handle newly purchased feeder cattle."--First page.Bonnard L. Moseley, DVM, (School of Veterinary Medicine) and Homer B. Sewell (Department of Animal Science College of Agriculture)Revised 5/90/5
Time-optimal Unitary Operations in Ising Chains II: Unequal Couplings and Fixed Fidelity
We analytically determine the minimal time and the optimal control laws
required for the realization, up to an assigned fidelity and with a fixed
energy available, of entangling quantum gates () between
indirectly coupled qubits of a trilinear Ising chain. The control is coherent
and open loop, and it is represented by a local and continuous magnetic field
acting on the intermediate qubit. The time cost of this local quantum operation
is not restricted to be zero. When the matching with the target gate is perfect
(fidelity equal to one) we provide exact solutions for the case of equal Ising
coupling. For the more general case when some error is tolerated (fidelity
smaller than one) we give perturbative solutions for unequal couplings.
Comparison with previous numerical solutions for the minimal time to generate
the same gates with the same Ising Hamiltonian but with instantaneous local
controls shows that the latter are not time-optimal.Comment: 11 pages, no figure
- …