${}^4$He in Nanoporous Media: 4D XY Quantum Criticality at Finite Temperatures

Abstract

We review our study of critical phenomena in superfluid ${}^4$He confined in nanoporous glasses. ${}^4$He in nanoporous media is an ideal ground to survey the quantum phase transition of bosons. In the present work, critical phenomena were examined using a newly developed hydrodynamic mechanical resonator. The critical exponent of superfluid density $\zeta$ was found to be 1.0, in contrast to 0.67 in bulk ${}^4$He. We also demonstrate that the superfluid density is proportional to $|P-P_{\mathrm{c}}{|}^{{\zeta }_p}$ with ${\zeta }_p=1$ at any finite temperatures. These are the decisive evidences for the 4D XY criticality, which should have been observed only at 0 K, at finite temperatures. We propose a mechanism of the quantum criticality at finite temperatures in terms of phase alignment among the nanoscale localized Bose condensates (LBECs) in nanopores. The proposed mechanism are discussed in the consideration of the correlation length compared with the quantum effect.

arXiv comment8 pages, 5 figures

References in corpus (10)

• Continuous Quantum Phase Transitions
• Thermodynamic Evidence for Nanoscale Bose-Einstein Condensation in ^4He Confined in Nanoporous Media
• Relation Between Pore Size and the Compressibility of a Confined Fluid
• 4D-XY quantum criticality in a doped Mott insulator
• Low frequency acoustics in solid ${}^4$He at low temperature
• Superfluidity of ${}^4$He Confined in Nano-Porous Media
• Search for supersolidity in 4He in low-frequency sound experiments
• Quantum Critical Phenomena of 4He in Nanoporous Media
• Evidence for 4D XY Quantum Criticality in ${}^4$He Confined in Nanoporous Media at Finite Temperatures
• 4D-XY Superfluid Transition and Dissipation in ${}^4$He Confined in Nanoporous Media