Atom chip makes thermodynamics quantum gas measurable
A team of researchers from the University of Amsterdam, The Netherlands, the Dutch Foundation of Fundamental Research on Matter and the University of Queensland, Australia, has succeeded in comparing temperature and density of a one-dimensional quantum gas to an exact theory that was developed back in 1969 by Nobel Laureate C.N. Yang and his brother, C.P. Yang. The results were published in the 7 March issue of Physical Review Letters and were selected as Editors’ Suggestion as a means of promoting reading across fields.
The experiments in Amsterdam were performed using an 'atom chip', a lithographically produced pattern of gold wires on a silicon substrate. By sending currents through the wires, a gas of rubidium atoms is magnetically trapped and cooled to the point where the atoms can only move in one dimension. The needle-shaped atomic cloud, with a width less than a percent of a human hair, is cooled to temperatures down to 100 nanoKelvin.
In this way, the first direct comparison was made possible between experiment and the nearly 40 years old Yang-Yang theory. The Yang-Yang exact solutions to the one-dimensional Bose gas model at finite temperature were once only a tour-de-force of mathematical and quantum many-body physics. The experimental techniques of laser cooling and magnetic trapping are now allowing physicists to precisely engineer these model systems in the laboratory.
In addition, the experiment allowed access to the momentum distribution of the gas. This distribution cannot be directly obtained using the Yang-Yang method and the measurement thus poses a new challenge to theory.
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The researchers: A.H. van Amerongen (UvA), J.J.P. van Es (FOM), P. Wicke (FOM), K.V. Kheruntsyan (Univ. Queensland, Australia) and N.J. van Druten (UvA).
Article: Yang-Yang thermodynamics on an Atom Chip, Physical Review Letters 100, 090402 (2008), see http://link.aps.org/abstract/PRL/v100/e090402 and http://staff.science.uva.nl/~druten/lop.html for the full article.
Aaldert van Amerongen will defend his thesis "One-dimensional Bose gas on an atom chip" on May 30, Universiteit van Amsterdam.
In 2002 Klaasjan van Druten has started a research group Quantum Gasses and Atomchips at the Van der Waals-Zeeman Institute of the University of Amsterdam using his NWO Vidi-grant.
The research was funded by NWO, FOM, ARC and the EU.
For more information, please contact Aaldert van Amerongen, +31 (0)6 12 75 44 51 and dr. Klaasjan van Druten, University of Amsterdam, +31 (0)20 525 71 18, or +31 (0)6 42 90 94 96.