The Momentum Distribution of Liquid ${}^4$He

Abstract

We report high-resolution neutron Compton scattering measurements of liquid ${}^4$He under saturated vapor pressure. There is excellent agreement between the observed scattering and ab initio predictions of its lineshape. Quantum Monte Carlo calculations predict that the Bose condensate fraction is zero in the normal fluid, builds up rapidly just below the superfluid transition temperature, and reaches a value of approximately $7.5\%$ below 1 K. We also used model fit functions to obtain from the scattering data empirical estimates for the average atomic kinetic energy and Bose condensate fraction. These quantities are also in excellent agreement with ab initio calculations. The convergence between the scattering data and Quantum Monte Carlo calculations is strong evidence for a Bose broken symmetry in superfluid ${}^4$He.

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References in corpus (10)

• Quantum fluids of light
• Mantid - Data Analysis and Visualization Package for Neutron Scattering and $\mu SR$ Experiments
• Bose-Einstein condensation of photons in an optical microcavity
• Worm Algorithm and Diagrammatic Monte Carlo: A New Approach to Continuous-Space Path Integral Monte Carlo Simulations
• Superfluidity and Quantum Melting of para-Hydrogen clusters
• Structure, superfluidity, and quantum melting of hydrogen clusters
• Neutron Stars in the Laboratory
• Bose-Einstein Condensate in Solid Helium
• The Momentum Distribution of Liquid ${}^3$He
• Momentum and Energy Dependent Resolution Function of the ARCS Neutron Chopper Spectrometer at High Momentum Transfer: Comparing Simulation and Experimen

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• The solid phase of He-4: A Monte Carlo simulation study
• Microscopic picture of superfluid ${}^4$He