Semiclassical Propagators for Quantum Coherent States and Applications of Extra Quantum Phase to Large-spin Tunneling of Magnetic Molecules
Park, Kee-Su
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/31330
Description
Title
Semiclassical Propagators for Quantum Coherent States and Applications of Extra Quantum Phase to Large-spin Tunneling of Magnetic Molecules
Author(s)
Park, Kee-Su
Issue Date
2001
Doctoral Committee Chair(s)
Stone, Michael
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
magnetic molecular systems
quantum tunneling
Language
en
Abstract
A continuous path integral is used to obtain the semiclassical expressions of quantum
propagators by means of coherent states in the holomorphic representation together
with the appropriate boundary conditions. It allows us to express the total actions
including boundary terms, classical trajectories, and extra phases in the stationary
phase approximation. In particular, in the semiclassical expression for the quantum
spin propagator, we pay attention to the extra quantum phase discovered by Solari
and Kochetov. It is shown that this extra phase is related to an anomaly in the
fluctuation determinant. It is verified that once this extra phase is included, the
semiclassical propagator leads to the correct short time behaviour to O(T²), and
shows its consistency under dissection of the path. In the application to the instanton
methods, the extra quantum phase yields the correct formula for the tunnel splitting
including both the exponential factor and the prefactor. The quantum phase leads
to the correct spectrum with a shift of the spin quantum number by 1/2. We apply
the semiclassical propagators and the tunnel splitting to a few models in magnetic
molecular systems. It is shown that the formula gives the correct exponential factor
and prefactors for quantum tunneling of a large spin if the extra quantum phase is
taken into account.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
