Decoupling of first sound from second sound in dilute 3He - superfluid 4He mixtures

2017-04-27 13:15:00 2017-04-27 14:00:00 Europe/Helsinki Decoupling of first sound from second sound in dilute 3He - superfluid 4He mixtures LTL Quantum Physics Seminar (Nanotalo). Speaker: T. Riekki (µKI). http://physics.aalto.fi/en/midcom-permalink-1e72591a2750142259111e7988d7f75bb8916761676 Puumiehenkuja 2, 02150, Espoo

LTL Quantum Physics Seminar (Nanotalo). Speaker: T. Riekki (µKI).

27.04.2017 / 13:15 - 14:00
Nanotalo, 161, Puumiehenkuja 2, 02150, Espoo, Otaniemi, FI

Bulk superfluid helium supports two sound modes: first sound is an ordinary pressure wave, while second sound is a temperature wave, unique to superfluid systems. These sound modes do not usually exist independently, but rather variations in pressure are accompanied by variations in temperature, and vice versa. We studied the coupling between first and second sound in dilute 3He - superfluid 4He mixtures, between 1.6 K and 2.2 K, at 3He concentrations ranging from 0 to 11%, under saturated vapor pressure, using a quartz tuning fork oscillator. Second sound coupled to first sound can create anomalies in the resonance response of the fork, which disappear only at very specific temperatures and concentrations, where two terms governing the coupling cancel each other, and second sound and first sound become decoupled.