When atoms behave as crystal and superfluid at the same time
Francesca Ferlaino
1. Institute for Experimental Physics, Universität Innsbruck, Austria
2. Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Science
Quantum physics often makes possible conceptual paradoxes, which appear ephemeral to our classical intuition. A recent example is the discovery of supersolid states in ultracold dipolar gases. Such states combine properties of superfluidity with those of a crystalline order.
This talk traces the fundamental steps for the observation of supersolidity from the perspective of the Innsbruck experiments. We will discuss how a quantum gas of erbium and dysprosium atoms spontaneously breaks its translational symmetry, creating a periodic modulation of its density, while maintaining a quantum phase coherence. We will show how in our experiments it is possible to drive the system to a supersolid phase transition either by cooling a thermal gas or by modifying the short-range interaction from an unmodulated dipolar condensate. Finally, we will report on the recent observation of extending the supersolid properties to two dimensions, and highlight the open questions which still remain to be understood.