Observation of a discrete time crystal
“Spontaneous symmetry breaking is a fundamental concept in
many areas of physics, including cosmology, particle physics and condensed
matter. An example is the breaking of spatial translational symmetry, which
underlies the formation of crystals and the phase transition from liquid to
solid. Using the analogy of crystals in space, the breaking of translational
symmetry in time and the emergence of a ‘time crystal’ was recently proposed,
but was later shown to be forbidden in thermal equilibrium. However,
non-equilibrium Floquet systems, which are subject to a periodic drive, can
exhibit persistent time correlations at an emergent subharmonic frequency. This
new phase of matter has been dubbed a ‘discrete time crystal’. Here we present
the experimental observation of a discrete time crystal, in an interacting spin
chain of trapped atomic ions. We apply a periodic Hamiltonian to the system
under many-body localization conditions, and observe a subharmonic temporal
response that is robust to external perturbations. The observation of such a
time crystal opens the door to the study of systems with long-range
spatio-temporal correlations and novel phases of matter that emerge under
intrinsically non-equilibrium conditions.”
No comments:
Post a Comment