Detecting a phonon flux in superfluid <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>He</mml:mi><mml:mprescripts /><mml:none /><mml:mn>4</mml:mn></mml:mmultiscripts></mml:math> by a nanomechanical resonator

Nanomechanical resonators are extremely sensitive force detectors and, therefore, provide fantastic probes for superfluids at low temperatures. The authors show that a nanomechanical resonator can detect the modulated flux of thermal phonons (`phonon wind') in superfluid {}^{4}e at millikelvin temperatures. To do this, they set up a modulated flux of phonons by passing an ac current through a nearby heater. The phonons collide with the...