QFS2016 Book of Abstracts

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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