Bose-Einstein Condensate in Solid Helium

Abstract

We present neutron scattering measurements of the atomic momentum distribution, n(k), in solid helium under a pressure p = 41 bars and at temperatures between 80 mK and 500 mK. The aim is to determine whether there is Bose-Einstein condensation (BEC) below the critical temperature, T_c = 200 mK where a superfluid density has been observed. Assuming BEC appears as a macroscopic occupation of the k = 0 state below T_c, we find a condensate fraction of n_0 = (-0.10 \pm 1.20)% at T = 80 mK and n_0 = (0.08\pm0.78)% at T = 120 mK, consistent with zero. The shape of n(k) also does not change on crossing T_c within measurement precision.

4 pages, 5 figures (in press)

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• Pressure-driven flow of solid helium
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• The Momentum Distribution of Liquid ${}^4$He
• Torsional oscillators and the entropy dilemma of putative supersolid He-4
• Instanton theory for bosons in disordered speckle potential
• Zero-temperature dynamics of solid 4He from quantum Monte Carlo simulations
• Search for supersolid 4He in neutron scattering experiments at ISIS
• Shear modulus in viscoelastic solid ${}^4$He
• Two-body correlations and the superfluid fraction for nonuniform systems
• Roton-like mode in solid He-4
• The solid phase of He-4: A Monte Carlo simulation study
• Saga of Superfluid Solids
• Parent Hamiltonians of Jastrow Wavefunctions