Neutron scattering measurements of the elementary excitations and of Bose-Einstein condensation (BEC) in quantum liquids confined in porous media reveal a possible

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Excitations and Bose-Einstein Condensation in
Quantum Liquids in Disorder Henry R. Glyde,
University of Delaware, DMR-9972011
Neutron scattering measurements of the elementary
excitations and of Bose-Einstein condensation
(BEC) in quantum liquids confined in porous media
reveal a possible mixed quantum state in
disorder. In this mixed state there is evidence
for BEC but there is no superfluidity.
Measurements are made at the Institut Laue
Langevin, Grenoble, France and at the ISIS
Facility, Rutherford Appleton Laboratory, UK.
Liquid 4He confined in porous media is an example
of Bosons in disorder. Other examples are
Cooper pairs in High Tc materials, flux lines in
High Tc materials and Josephson Junction Arrays.
We find that the characteristic phonon-roton
excitations of superfluid 4He are remarkably
little modified by disorder. However, new
excitations propagating in the liquid layers near
the porous media surfaces appear. These new
excitations can be related to thermodynamic
properties in disorder. Most interestingly, our
data shows evidence for localized BEC, or a
Bose glass state, in disorder at temperatures
immediately above the superfluid phase where
there is BEC but no macroscopic superflow.
Figure 1. Top The Insitiut Laue Langevin (just
behind the ESRF synchrotron ring) in Grenoble.
Bottom Left to right, Jacques Bossy, Henry
Glyde, Francesco Albergamo and Olivier Plantevin
in front of the IN6 neutron spectrometer of ILL.
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Excitations and Bose-Einstein Condensation in
Quantum Liquids in Disorder Henry R. Glyde,
University of Delaware, DMR-9972011
An educational goal is to train young scientists
in neutron scattering techniques in preparation
for the new Spallation Neutron Source (SNS) now
under construction at Oak Ridge National
Laboratory (ORNL). Associated with this research
are   Graduate Students F.
Albergamo - (PhD U. Paris), now a post-doc at

ILL/Delaware J. L. Dubois - PhD
Delaware, summer 2002 A. R. Sakhel
- PhD Delaware, summer 2003   Post-doctoral
Associates R. T. Azuah - now
instrument scientist at NIST
Center for Neutron
Research, Gaithersburg, MD
O. Plantevin - now instrument
scientist at ESRF,
Grenoble   Collaborators B.
Fåk - ISIS Facility, Rutherford
Appleton Lab, UK J.
Bossy - CNRS/ILL, Grenoble, France
W. G. Stirling - ESRF, Grenoble
Figure 2. Discussing analsis of neutron
scattering data at Delaware are (left to right)
Zhicheng Yan, Richard Azuah, Assad Sakhel,
Jonathan DuBois, and Henry Glyde.