Theory Scientific News

Category for scientific news related to the theory group.

Topology meets superconductivity in a one-dimensional t-J model of magnetic atoms

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We have published a new paper by our theory + erbium team on arxiv!

In this work, we leverage the special properties of ultracold magnetic lanthanide atoms trapped in optical lattices, to create a highly controllable version of the iconic t-J model, a cornerstone of quantum many-body physics. We uncover a wide range of exotic phases, including superconducting, topological, and—most strikingly—topological superconducting states. The latter presents several aspects of novelty. The most intriguing one is that differently from the paradigmatic example of one-dimensional topological superconductivity appearing in the celebrated Kitaev chain, this phase is purely induced by competing interactions. We also outline how these phases can be realized and detected with current experimental tools, opening a powerful new route for a deeper understanding of strongly interacting fermionic quantum matter.

Light-Assisted Collisions in Tweezer-Trapped Lanthanides

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Read our latest paper published on arxiv!

We present a quantitative investigation of one- and two-body light-mediated processes that occur to few erbium atoms in an optical tweezer, when exposed to near-resonant light. Using our ultrafast imaging technique with blue light, we are able to track the in-tweezer population dynamics during light-assisted collision and cooling processes.

To gain deeper insights into the underlying physics, we develop and implement a Monte Carlo algorithm that simulates the coupled dynamics of the atoms’ internal and external degrees of freedom. After validating our theoretical model against experimental data, we use its predictive capabilities to guide our experimental design. In particular, we examine how different erbium transitions influence light-assisted collisions, with a focus on optimizing their efficiency and reliability for preparing single atoms.

Dancing supersolids synchronize

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In collaboration between the Er-Dy Lab and the Theory subgroup, and Dr. Giacomo Lamporesi at the BEC centre in Trento, our new pre-print reveals a fundamental difference in a supersolid’s response to rotation in absence or presence of a quantum vortex. This work builds on our previous investigation of vortices in supersolids, showing that the superfluid and solid natures synchronize to the external rotation only when there are vortices in the state. We verify this theoretical prediction in the experiment, revealing the route to vortex nucleation in supersolids.

See the pre-print here: https://arxiv.org/abs/2412.11976

Vortices in a dipolar supersolid

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Now published in Nature!

In an internal collaboration between the Er-Dy Lab and the Theory subgroup, our new pre-print reveals a fundamental difference in vortex nucleation between the unmodulated superfluid and the modulated 2D supersolid phase of dipolar BECs. This work builds on our previous investigation of vortices in dipolar gases (see our writeups here and here) and of supersolids with two-dimensional crystalline order (see our writeup here). This opens the door to study the hydrodynamic properties of exotic quantum systems with multiple spontaneously broken symmetries, ranging from quantum crystals to neutron stars — for a general overview of the connection between glitches in the supersolid and neutron stars, see our writeup here.

See the article in Nature here: Observation of vortices in a dipolar supersolid

Read the pre-print here: arXiv:2403.18510.

Read the feature by Quanta Magazine here: Physicists spot quantum tornadoes twirling in a supersolid

Excitations of a two-dimensional supersolid

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Now published in the journal “Physical Review A”!  The newest work from the Theory group are the results of PhD student Elena Poli’s DK-ALM research stay abroad in the group of Professor Blair Blakie at the University of Otago, NZ. In this theory paper, they study the excitations and elastic parameters of the 2D supersolid state of a BEC with dipolar interactions and soft-core interactions. See the following excerpt from the abstract for some of the details of this collaborative effort:

[The] supersolid state has three gapless excitation branches arising from the spontaneously broken continuous symmetries. Two of these branches are related to longitudinal sound waves, similar to those in one-dimensional supersolids. The third branch is a transverse wave arising from the non-zero shear modulus of the two-dimensional crystal. We present the results of numerical calculations for the excitations and dynamic structure factor characterising the density fluctuations, and study their behavior across the discontinuous superfluid to supersolid transition. We show that the speeds of sound are described by a hydrodynamic theory that incorporates generalized elastic parameters, including the shear modulus. Furthermore, we establish that dipolar and soft-core supersolids manifest distinct characteristics, falling into the bulk incompressible and rigid lattice limits, respectively.

See the article in PRA here: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.053301
See the pre-print here: Excitations of a two-dimensional supersolid https://arxiv.org/abs/2407.01072.

Spektrum magazine article: glitches in supersolids and neutron stars for Sterne und Weltraum

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For German speakers: in this month’s edition of ‘Sterne und Weltraum’ of Spektrum magazine, you will find an article  about the links between glitches in supersolids and in neutron stars, written by our very own Elena Poli, Thomas Bland, Manfred Mark, and Francesca Ferlaino, alongside frequent collaborator, Massimo Mannarelli.

Read the article here: https://www.spektrum.de/news/pulsare-quantenwirbel-beschleunigen-neutronensterne/2206793

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