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At the interface between two fluid layers in relative motion, infinitesimal fluctuations can be exponentially amplified, inducing vorticity and the breakdown of laminar flow. While shear-flow instabilities in classical fluids have been extensively observed in various contexts, controlled experiments in the presence of quantized circulation are quite rare. In our last work, we observe how the contact interface between two counter-rotating atomic superflows develops into an ordered circular array of quantized vortices, which loses stability and rolls up into vortex clusters. We extract the instability growth rates and find that they obey the same scaling relations across different superfluid regimes, ranging from weakly-interacting bosonic to strongly-correlated fermionic pair condensates. Our results establish connections between vortex arrays and shear-flow instabilities, suggesting a possible interpretation of the observed quantized vortex dynamics as a manifestation of the underlying unstable flow. Moreover, they open the way for exploring out-of-equilibrium phenomena such as vortex-matter phase transitions and the spontaneous emergence and decay of two-dimensional quantum turbulence. D. Henández-Rajkov et al. |
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!
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We have completed the optical setup for the 689 nm laser source that will be employed for further cool the Strontium atoms by a factor of 1000 in a red 3D MOT, in order to reach a temperature of few micro Kelvin. A significant challenge we faced was stabilizing the frequency of the red laser to a very stable and very high finesse ultra-low expansion cavity. |
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We are immensely proud of Giulio Biagioni, who has defended his doctoral thesis "Can a superfluid be solid? A study of the supersolid phase in a dipolar quantum gas", achieving the summa cum laude distinction. In the last few years, Giulio has given invaluable contributions to our research, enriching our group in countless ways and inspiring many experiments. We wish him all the success and fulfillment he deserves, and even more luck in his academic journey! See also the thesis |
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Congrats and good luck Bea! |
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We are thrilled to welcome Dr. Chiara Mazzinghi to our team! Chiara brings a wealth of expertise and fresh perspectives to our group. We look forward to the exciting collaborations ahead and the innovative ideas she will contribute! |