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arXiv · 2104.05934

Evidence for 4D XY Quantum Criticality in $^4$He Confined in Nanoporous Media at Finite Temperatures

Tomoyuki Tani·Yusuke Nago·Satoshi Murakawa·Keiya Shirahama
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Abstract

$^4$He confined in nanoporous media is a model Bose system that exhibits quantum phase transition (QPT) by varying pressure. We have precisely determined the critical exponent of the superfluid density of $^4$He in porous Gelsil glasses with pore size of 3.0 nm using the Helmholtz resonator technique. The critical exponent $\zeta$ of the superfluid density was found to be 1.0 $\pm$ 0.1 for the pressure range 0.1 < P < 2.4 MPa. This value provides decisive evidence that the finite-temperature superfluid transition belongs to the four-dimensional (4D) XY universality class, in contrast to the classical 3D XY one in bulk liquid 4He, in which $\zeta$ = 0.67. The quantum critical behavior at a finite temperature is understood by strong phase fluctuation in local Bose-Einstein condensates above the superfluid transition temperature. $^4$He in nanoporous media is a unique example in which quantum criticality emerges not only at 0 K but at finite temperatures.

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Tomoyuki Tani, Yusuke Nago, Satoshi Murakawa, Keiya Shirahama. 2021-04-13. Evidence for 4D XY Quantum Criticality in $^4$He Confined in Nanoporous Media at Finite Temperatures. https://doi.org/10.7566/jpsj.90.033601

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