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Proceedings Paper

Quantum crystals: from quantum plasticity to supersolidity
Author(s): S. Balibar; A. Haziot; X. Rojas
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Paper Abstract

We have discovered that helium-4 crystals are anomalously soft around one tenth of a Kelvin (100 mK) if totally free of impurities. Their plasticity is large, due to quantum effects. This is because their dislocations can move macroscopic distances (typically 0.1 mm) at high speed (meters per second) under the effect of stresses as small as 1 microbar. In classical crystals all atoms are completely frozen at low temperature. But in quantum crystals such as helium-4, quantum fluctuations are large and atoms can jump by quantum tunneling from site to site, especially at the core of dislocation lines where the packing is not as compact as elsewhere. We have shown that highly mobile dislocations reduce the stiffness of helium-4 crystals by one order of magnitude. However, very tiny traces of helium-3 impurities are sufficient to stop the motion of dislocations when they attach to them below temperatures of order 100 mK. Apparently, this is what drives these crystals to a "supersolid state", an astonishing new state of matter where superfluidity coexists with crystalline order. We think that the core of dislocations becomes superfluid only when the dislocation lines themselves stop moving.

Paper Details

Date Published: 24 January 2011
PDF: 7 pages
Proc. SPIE 7945, Quantum Sensing and Nanophotonic Devices VIII, 794502 (24 January 2011); doi: 10.1117/12.879862
Show Author Affiliations
S. Balibar, Lab. de Physique Statistique de l'Ecole Normale Supérieure, CNRS, Univ. Paris 6 and 7 (France)
A. Haziot, Lab. de Physique Statistique de l'Ecole Normale Supérieure, CNRS, Univ. Paris 6 and 7 (France)
X. Rojas, Lab. de Physique Statistique de l'Ecole Normale Supérieure, CNRS, Univ. Paris 6 and 7 (France)


Published in SPIE Proceedings Vol. 7945:
Quantum Sensing and Nanophotonic Devices VIII
Manijeh Razeghi; Rengarajan Sudharsanan; Gail J. Brown, Editor(s)

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