Density Fluctuations across the Superfluid-Supersolid Phase Transition in a Dipolar Quantum Gas

Understand

Phase transitions share the universal feature of enhanced fluctuations near the transition point.

• Here we show that density fluctuations reveal how a Bose-Einstein condensate of dipolar atoms spontaneously breaks its translation symmetry and enters the supersolid state of matter -- a phase that combines superfluidity with crystalline order.
• We report on the first direct in situ measurement of density fluctuations across the superfluid-supersolid phase transition.
• This allows us to introduce a general and straightforward way to extract the static structure factor, estimate the spectrum of elementary excitations and image the dominant fluctuation patterns.