Quantum Polyamorphism in Helium-4 Glass under the Boltzmann Statistics

Abstract

We have found that two amorphous solid states can exist in ⁴He obeying the Boltzmann statistics under compressed conditions. The states are distinguished by quantum wavelength of atoms, and are called low and high quantum dispersion amorphous solids (LQDA and HQDA). The existence of the two states indicates the quantum polyamorphism in this system. The state transition occurs reversibly by varying pressure or temperature, while it resembles the coil-globule transition in classical polymer systems. The atomic diffusion in HQDA is enhanced by compression or cooling. This enhancement of atomic diffusivity is explained by the existence of atomic tunneling in the HQDA. The present finding suggests that this new type of polyamorphism is involved in the real ⁴He.