Evidence for a Second Order Phase Transition in Glasses at Very Low Temperatures -- A Macroscopic Quantum State of Tunneling Systems

P. Strehlow, C. Enss, S. Hunklinger

Dielectric measurements at very low temperature indicate that in a glass with the eutectic composition BaO-Al${}_2$O${}_3$-SiO${}_2$ a phase transition occurs at 5.84 mK. Below that temp…