We aim to widen the range of quantum simulations with cold atoms, by investigating phenomena arising from the long-ranged dipolar interaction in reduced dimensionalities. We are operating a new experimental setup based on quantum gases of the highly magnetic Dysprosium atoms. This is a joint project between LENS and CNR-INO, Sezione di Pisa.

The paradoxical supersolid phase of matter has the apparently incompatible properties of crystalline order and superfluidity. A crucial feature of a one-dimensional supersolid is the occurrence of two gapless excitations reflecting the Goldstone modes associated with the spontaneous breaking of two continuous symmetries: the breaking of phase invariance, corresponding to the locking of the phase of the atomic wave functions at the origin of superfluid phenomena, and the breaking of translational invariance due to the lattice structure of the system. We demonstrate the supersolid nature of the coherent stripe regime we discovered in dipolar Bose-Einstein condensates. In our trapped system, the symmetry breaking appears as two distinct compressional oscillation modes, reflecting the gapless Goldstone excitations of the homogeneous system. We observe that the two modes have different natures, with the higher frequency mode associated with an oscillation of the periodicity of the emergent lattice and the lower one characterizing the superfluid oscillations. Our work paves the way to explore the two quantum phase transitions between the superfluid, supersolid and crystal-like configurations that can be accessed by tuning a single interaction parameter.

L. Tanzi, et al.
Supersolid symmetry breaking from compressional oscillations in a dipolar quantum gas
Nature 574, 382 (2019)

See also the Nature News and Views by S. M. Mossman:

S. M. Mossman, Sounds of a supersolid detected in dipolar atomic gases for the first time
Nature 574, 341 (2019)

and the Nature Physics research highligh by Y. Li:

Y. Li, The buried trace
Nature Physics 15, 986 (2019)

The competition of dipole-dipole and contact interactions leads to exciting new physics in dipolar gases, well-illustrated by the recent observation of quantum droplets and rotons in dipolar condensates. We have now discovered that the combination of the roton instability and quantum stabilization leads under proper conditions to a novel regime that presents supersolid properties, due to the coexistence of periodic density modulation and phase coherence. In a combined experimental and theoretical analysis (with the University of Hannover), we have determined the parameter regime for the formation of coherent stripes, whose lifetime of a few tens of milliseconds is limited by the eventual destruction of the stripe pattern due to three-body losses. Our results open intriguing prospects for the development of long-lived dipolar supersolids.

L. Tanzi et al.
Observation of a dipolar quantum gas with metastable supersolid properties
Phys. Rev. Lett. 122, 130405 (2019)

See also the reviews on Physics Viewpoint by T. Donner:

T. Donner, Dipolar Quantum Gases go Supersolid
Physics 12, 38 (2019)
also featured in Highlights of the Year, Physics 12, 145 (2019)

and the Nature News and Views by L. Pollet:

L. Pollet, Quantum gases show flashes of a supersolid
Nature 569, 494 (2019)

We have characterized the scattering properties of ultracold 162Dy atoms for magnetic fields between 6 and 30 G. In addition to the typical chaotic distribution of narrow Feshbach resonances in Lanthanides, we have discovered two rather isolated broad features. A characterization using the complementary measurements of losses, thermalization, anisotropic expansion and molecular binding energy points towards resonances of predominant s-wave character, with dimensionless strength s=0.5(3). Such resonances will ease the investigation of quantum phenomena relying on the interplay between dipole and contact interactions.

E. Lucioni, et al.
Dysprosium dipolar Bose-Einstein condensate with broad Feshbach resonances
Phys. Rev. A 97, 06060701(R) (2018)

We observed the transition to BEC for 162Dy atoms!
Our dipolar BECs are made up at the moment by up to 3⨯104 atoms. Atoms from the MOT are transferred into an in-vacuum optical resonator where we perform a first evaporation down to a few μK. Afterwards, we load the atoms in a crossed optical trap and condensation temperature is reached by evaporation ramps. The atomic dipoles are aligned along the vertical direction by an uniform magnetic field of a few Gauss and the vertical trapping frequency is higher than the horizontal ones to prevent dipolar collapse. The transition temperature for our trapping potential is below 100 nK.

We realize a magneto-optical trap for 162Dy atoms on the intermediate linewidth transition at 626 nm. We trap over 2✕108 atoms at temperatures as low as 20 μK in 5 seconds. We observe the best loading at large detuning, -35Γ. Under these operating conditions, MOT forms below the quadrupole centre and the MOT light acts as optical pumping as well.

E. Lucioni et al.
A new setup for experiments with ultracold Dysprosium atoms
Eur. Phys. J. Spec. Top. 226, 2775 (2017)

We finished assembling the vacuum setup. In the final cell, we included a passive high finesse optical resonator to transfer a large volume of atoms from the MOT to an optical trap that requires low power.

Light at 421nm will be employed for transverse cooling and for the Zeeman slower. Up to 1.2W of blue light is produced in a homemade frequency doubling cavity and is locked to the atomic line using saturated absorption spectroscopy in a hollow cathode lamp.

Light at 626nm will be employed for the magneto-optical trap (MOT). The red light is obtained from a commercial laser system and is locked to the atomic line using saturated absorption spectroscopy in a iodine cell.

Dy People

Giulio Biagioni
Master student
Juliàn Gabriel Maloberti
Master student
Luca Tanzi
Scientific staff
Andrea Fioretti
Scientific staff
Carlo Gabbanini
Scientific staff
Giovanni Modugno
Scientific staff
Former members and collaborators:
Jacopo Catani
Silvia Gozzini
Massimo Inguscio
Eleonora Lucioni

Dy contacts

For further information, request of material, job opportunities, please contact:

Giovanni Modugno
(modugno@lens.unifi.it)

Dy funding