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Abstracts
P4.22
Compact 1K Rotating Cryostat for Helium 4 Experiment
Makiuchi, T.(1), Murakawa, S.(2), Shirahama, K.(1)
(1) Keio University, Faculty of Science and Technology, Department of Physics,
Yokohama, 223-8522, Japan
(2) University of Tokyo, Cryogenics Research Center, Bunkyo, 113-0032, Japan
For studies of novel phenomena of superfluid helium 4 in a nanoscale confinement,
we constructed a compact, inexpensive and easily-operated 1K rotating cryostat
in Keio University. A rotating system consists of a dewar, a cryostat insert and all
the electronic instruments fixed tight on two round tables. The system is rotated
by a servo motor underneath the dewar. Using a computer in a laboratory frame,
one can control the rotation and collect data from the rotating instruments via
Wi-Fi. The maximum rotation angular velocity is 6 rad/s, which is greater than
typical critical angular velocities of superfluid helium 4. The performance of the
rotating system and the cryostat will be shown.
P4.23
Fast coherent control of Bose-Einstein condensates without unwanted
excitations
Masuda Shumpei
Aalto
University,
Department
of
Applied
Physics,
QCD Labs, P.O. Box 13500, FIN-00076 Aalto, Finland
Various control schemes of the dynamical evolution of quantum systems have been
proposed. The control schemes rely on coherence and interference effects embedded
in the quantum dynamics of the system, and vary in efficiency, generality of
application, and sensitivity to perturbations. Adiabatic dynamics of a quantum
system is useful when external field-generated variation of the Hamiltonian is
used to manipulate the system’s evolution. However, an adiabatic process must
be carried out very slowly. In such slow processes, decoherence caused by the
interaction with environment can degrade the fidelity of the control. Recognition
of this restriction has led to the development of control protocols, which we call
assisted adiabatic transformations or shortcut to adiabaticity. In this talk, we
show fast controls of Bose-Einstein condensates using the fast-forward protocol.
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