Evidence of 4He Crystallization via Quantum Tunneling at mK Temperatures

We have investigated creation of 4He crystals from the superfluid phase at the temperature range 2 mK–1.0 K. Statistical nucleation-event distributions in overpressure were found to be broad, asymmetric, and temperature independent below 100 mK. Our statistical analysis agrees with a theoretical model suggesting that solid formation is driven by macroscopical quantum-mechanical fluctuations from a seed preexisting in a cavity on the wall.Peer reviewe