12 research outputs found
Level Splitting in Association with the Multiphoton Bloch-Siegert Shift
We present a unitary equivalent spin-boson Hamiltonian in which terms can be
identified which contribute to the Bloch-Siegert shift, and to the level
splittings at the anticrossings associated with the Bloch-Siegert resonances.
First-order degenerate perturbation theory is used to develop approximate
results in the case of moderate coupling for the level splitting.Comment: 8 pages, 2 figure
Multiphoton Bloch-Siegert shifts and level-splittings in spin-one systems
We consider a spin-boson model in which a spin 1 system is coupled to an
oscillator. A unitary transformation is applied which allows a separation of
terms responsible for the Bloch-Siegert shift, and terms responsible for the
level splittings at anticrossings associated with Bloch-Siegert resonances.
When the oscillator is highly excited, the system can maintain resonance for
sequential multiphoton transitions. At lower levels of excitation, resonance
cannot be maintained because energy exchange with the oscillator changes the
level shift. An estimate for the critical excitation level of the oscillator is
developed.Comment: 14 pages, 3 figure
Excitation transfer in two two-level systems coupled to an oscillator
We consider a generalization of the spin-boson model in which two different
two-level systems are coupled to an oscillator, under conditions where the
oscillator energy is much less than the two-level system energies, and where
the oscillator is highly excited. We find that the two-level system transition
energy is shifted, producing a Bloch-Siegert shift in each two-level system
similar to what would be obtained if the other were absent. At resonances
associated with energy exchange between a two-level system and the oscillator,
the level splitting is about the same as would be obtained in the spin-boson
model at a Bloch-Siegert resonance. However, there occur resonances associated
with the transfer of excitation between one two-level system and the other, an
effect not present in the spin-boson model. We use a unitary transformation
leading to a rotated system in which terms responsible for the shift and
splittings can be identified. The level splittings at the anticrossings
associated with both energy exchange and excitation transfer resonances are
accounted for with simple two-state models and degenerate perturbation theory
using operators that appear in the rotated Hamiltonian.Comment: 26 pages, 4 figure
Multiphoton Bloch-Siegert shifts and level-splittings in a three-level system
In previous work we studied the spin-boson model in the multiphoton regime,
using a rotation that provides a separation between terms that contribute most
of the level energies away from resonance, and terms responsible for the level
splittings at the anticrossing. Here, we consider a generalization of the
spin-boson model consisting of a three-level system coupled to an oscillator.
We construct a similar rotation and apply it to the more complicated model. We
find that the rotation provides a useful approximation to the energy levels in
the multiphoton region of the new problem. We find that good results can be
obtained for the level splittings at the anticrossings for resonances involving
the lower two levels in regions away from accidental or low-order resonances of
the upper two levels.Comment: 29 pages, 13 figure
Optics and Quantum Electronics
Contains table of contents for Section 3 and reports on twenty-one research projects.Joint Services Electronics Program Contract DAAL03-89-C-0001Joint Services Electronics Program Contract DAAL03-92-C-0001U.S. Air Force - Office of Scientific Research Contract F49620-91-C-0091Charles S. Draper Laboratories Contract DL-H-441629MIT Lincoln LaboratoryCharles S. Draper Laboratories, Inc. Contract DL-H-418478Fujitsu LaboratoriesNational Science Foundation Grant ECS 90-12787National Center for Integrated PhotonicsNational Science Foundation Grant EET 88-15834National Science Foundation Grant ECS 85-52701U.S. Air Force - Office of Scientific Research Contract F49620-88-C-0089U.S. Navy - Office of Naval Research Contract N00014-91-C-0084U.S. Navy - Office of Naval Research Grant N00014-91-J-1956Johnson and Johnson Research GrantNational Institutes of Health Contract 2-R01-GM35459U.S. Department of Energy Grant DE-FG02-89 ER14012-A00
Optics and Quantum Electronics
Contains table of contents for Section 3 and reports on twenty-three research projects.Joint Services Electronics Program Contract DAAL03-92-C-0001U.S. Air Force - Office of Scientific Research Contract F49620-91-C-0091Charles S. Draper Laboratories Contract DL-H-441629MIT Lincoln LaboratoryNational Science Foundation Grant ECS 90-12787Fujitsu LaboratoriesU.S. Navy - Office of Naval Research Grant N00014-92-J-1302National Center for Integrated PhotonicsNational Center for Integrated Photonics TechnologyNational Science Foundation Grant EET 88-15834Joint Services Electronics Program Contract DAAL03-91-C-0001National Science Foundation Fellowship ECS-85-52701U.S. Navy - Office of Naval Research (MGH) Contract N00014-91-C-0084U.S. Navy - Office of Naval Research Grant N00014-91-J-1956National Institutes of Health Grant NIH-5-RO1-GM35459-08Bose CorporationLawrence Livermore National Laboratories Subcontract B160530U.S. Department of Energy Grant DE-FG02-89-ER14012Rockwell International CorporationSpace Exploration AssociatesFuture Energy Applied Technology, Inc