Taming, slowing and trapping atoms with light
Cold is quantum, Quantum is cool!
We shape quantum matter
Multicolored lasers for a variety of atoms
Keeping our eyes on the quantum world
Join our ultracool group!
High technology for great science

Welcome to the website of the Ultracold Quantum Gases group at the European Laboratory for Nonlinear Spectroscopy (LENS), the Department of Physics and Astronomy of the University of Florence (Italy) and the Institute of Optics of the Italian National Research Council (CNR - INO). In our labs we use lasers and magnetic fields to produce the lowest temperatures of the Universe, just a few billionths of a degree above absolute zero...

At these temperatures, atoms stop moving and we can control them for a variety of different fundamental studies and applications. We can force atoms to arrange according to a periodic structure and simulate the behavior of crystalline solids and new materials. We can use the atoms as ultra-high accurate sensors to probe forces with the power of quantum mechanics. We can study how quantum particles combine together under the action of strong interactions and how superfluidity develops. We can use these ultracold atoms to process information and develop new quantum technologies.

Dress warmly and... follow us for this ultracold journey!


A closed-trajectory evolution of a quantum state generally imprints a phase that contains both dynamical and geometrical contributions. While dynamical phases depend on the reference system, geometric phase factors are uniquely defined by the properties of the outlined trajectory. Here, we generate and measure geometric phases in a Bose-Einstein condensate of 87Rb using a combination of dynamical quantum Zeno effect and measurement-free evolution. We show that the dynamical quantum Zeno effect can inhibit the formation of a geometric phase without altering the dynamical phase. This can be used to extract the geometric Aharonov-Anandan phase from any closed-trajectory evolution without requiring knowledge or control of the Hamiltonian.

H.–V. Do et al.,
Measuring geometric phases with a dynamical quantum Zeno effect in a Bose-Einstein condensate
Phys. Rev. Research 1, 033028 (2019)

We report on the study of binary collisions between quantum droplets formed by an attractive mixture of ultracold atoms. We distinguish two main outcomes of the collision, i.e., merging and separation, depending on the velocity of the colliding pair. The critical velocity vc that discriminates between the two cases displays a different dependence on the atom number N for small and large droplets. By comparing our experimental results with numerical simulations, we show that the nonmonotonic behavior of vc is due to the crossover from a compressible to an incompressible regime, where the collisional dynamics is governed by different energy scales, i.e., the droplet binding energy and the surface tension. These results also provide the first evidence of the liquidlike nature of quantum droplets in the large N limit, where their behavior closely resembles that of classical liquid droplets.

G. Ferioli et al.,
Collisions of Self-Bound Quantum Droplets
Phys. Rev. Lett. 122, 090401 (2019)

Lorenzo Francesco Livi has been awarded with a prize from Florence University Press for the best PhD thesis discussed in 2018 at University of Florence among all the scientific disciplines. The prize will consist in the publication of the thesis, titled "New quantum simulations with ultracold Ytterbium gases", by Florence University Press. The diploma has been given to Lorenzo by Prof. Luigi Dei, Rector of the University of Florence, in a public ceremony. Congratulations!

Lorenzo Francesco Livi
New quantum simulations with ultracold Ytterbium gases
PhD thesis - University of Firenze (2018)

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)

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Seminars & Events

Seminar by Prof. Carlos Sa de Melo:
Ultra-cold Fermi Gases with Three and Four Internal States: The Evolution from BCS to BEC Superfluidity in Multiband Systems ,
h. 12.00 Querzoli room, LENS.
Seminar by Dr. Dimitrios Trypogeorgos:
Unconventional topology with a Rashba spin-orbit coupled quantum gas,
h. 14.30 Querzoli room, LENS.
Firenze-Trieste workshop:
Two days of talks and scientific discussions with the theory groups of ICTP and SISSA,
ICTP, Trieste.
Firenze-Trieste workshop:
Two days of talks and scientific discussions with the theory groups of ICTP and SISSA,
Aula Querzoli, LENS.
Quantumgases retreat:
A full-day group meeting to discuss the activity of the different labs,
h. 9.00 Villa il Gioiello, Arcetri.
Fermi Colloqium by Prof. Wolfgang Ketterle:
New forms of matter with ultracold atoms: superfluids, supersolids and more,
h. 11.30 Querzoli room, LENS.
Seminar by Prof. Arno Rauschenbeutel:
Chiral Quantum Optics,
h. 11.00 Querzoli room, LENS.
The LENS QuantumGases group is glad to welcome in Florence Prof. Randall Hulet from Rice University. Prof. Hulet will be our guest for one month until mid July.