Lecturer: Dr. Anna Eyal
Affiliation: Cornell University
Abstract:
Liquid helium 4 undergoes a phase transition
into a superfluid at low temperatures. Owing
to its quantum nature, the solid phase of
helium 4 has been suggested to host a
similar type of Bose-condensed state,
supporting frictionless mass flow. This
unique phenomenon has been termed
supersolidity.
In the past decade, the existence of
supersolidity has been alternately confirmed
and disproved experimentally. The
controversy originates from the fact that a
small supersolid signal can be
overshadowed by large elastic effects arising
from an anomaly in the shear modulus of the
solid.
Using a novel experimental approach, with
specially-designed multi-mode torsional
oscillators, we were able to accurately
distinguish between the different
contributions for the first time, and
discovered a small frequency-independent
signal, as expected in the presence of a
supersolid phase.
I will discuss the significance of our results in
the broader context of the field's current
state.