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Abstract:
Unitary integration is a numerical method that preserves the structure of the quantum Liouville equation by evolving the density via unitary transformations. Unitary integrators preserve the kinematic invariants C(sub j) = trp(sup j), j = 1,..., n to all orders in the time step. Here we extend unitary integration to weakly dissipative systems. We apply the technique of operator splitting, using a unitary integrator for the Hamiltonian evolution and a conventional integrator for the dissipative piece. In this way, we guarantee that all dissipation and decoherence (variation of the C(sub j)) is due to the new non-Hamiltonian terms and not to any numerical artifacts. We illustrate the method with examples.
| Limitations: |
 APPROVED FOR PUBLIC RELEASE |
| Pages: |
20 |
| Report Date: |
20 JUN 2001 |
| Contract Number: |
F04701-00-C-0009 |
| Report Number: |
A111593 |
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Keywords relating to this report:
