Quantum Glass in Solid He?

Recent discovery of a possible supersolid state by Kim and Chan has stimulated an active debate about true nature of a low temperature state of solid $^{ 4}$He. We will discuss possible glassy component that could be present in solid $^{ 4}$He. We will focus on i) the role of tunneling systems (TS) as a component that freezes out at lowest temperatures and ii) interactions between TS. We will address possible quantum effects and the role of TS statistics in solid $^{4}$He vs solid $^{ 3}$He-$^{ 4}$He mixtures. Implications for the torsional oscillator and for thermodynamics will be discussed as well.