Momentum deficit in quantum glasses

TL;DR

This paper explains the observed reduction in rotational inertia of disordered solid helium-4 using quantum tunneling two-level systems, revealing a novel quantum state with unique properties distinct from normal and superfluid solids.

Contribution

It introduces the concept of momentum deficit in quantum glasses, providing a new explanation for experimental observations in disordered solid helium-4.

Findings

Reduced rotational inertia observed in experiments

Absence of superflow in the proposed state

Normal behavior in steady rotation

Abstract

Using the concept of tunneling two level systems we explain the reduction of rotational inertia of disordered solid 4He observed in the torsional oscillator experiments. The key point is a peculiar quantum phenomenon of momentum deficit for two level systems in moving solids. We show that an unusual state which is essentially different from both normal and superfluid solid states can be realized in quantum glasses. This state is characterized by reduced rotational inertia in oscillator experiments, by absence of a superflow, and by normal behavior in steady rotation.