Quantum simulations with long-range interactions
Experimental observation of a dipolar supersolid. Typical momentum distribution of the atomic cloud for different evolution times in three regimes: BEC (top row), supersolid (middle row), and incoherent regime (bottom row).
In a supersolid, the axial breathing mode bifurcates: the higher frequency reflects the oscillation of the periodicity of the emergent lattice, the lower one is associated with the superfluid flow between different density maxima.
We use a quantum degenerate gas of dysprosium atoms, produced with laser cooling and evaporative techniques, to study quantum phase transitions to exotic states of matter and implement quantum simulations. The peculiar properties of Dy atoms, with their strong long-range interactions due to the extraordinarily large magnetic dipole moments, brought us to identify the long-sought “supersolid” state of matter, where a periodic density modulation and phase coherence can somehow coexist (Fig. 1). Our studies of the response of the supersolid to collective excitations and rotations have confirmed its peculiar double superfluid/solid nature (Fig. 2). We are now moving towards the study of two-dimensional supersolids, where rotational properties become even more apparent, and to the production of Dy dimers in an optical lattice, where the stronger interaction among molecules allows the implementation of quantum simulation schemes.