Abstract
With DiQuT, we plan to construct a versatile novel experimental platform that will grant access to both topological p-wave superfluids and to unexplored interacting topological phases on lattice geometries, where the combination of non-local interactions and topology could be analyzed in a controlled way. The novel platform will consist of a Bose-Fermi mixture of magnetic atoms. The theoretical work developed by the UNIBO unit is functional to its future application in the experimental system by the CNR-INO unit. The overall goal of DiQuT is the theoretical investigation and the experimental implementation of a novel quantum simulator specifically designed to simulate topological materials. This implies the following main objectives.1. The experimental realization of the quantum simulator, based on a BF dipolar mixture with tunable BF coupling.2. The deep theoretical investigation of p-wave superfluidity in dipolar BF mixtures, and the first experimental characterization of p-wave scattering.3. The theoretical investigation of topological phases in lattice models 1. Experimental realization of a dipolar BF mixture with tunable BF interaction couplings; 2. Theoretical phase diagram for the competition between boson condensation and p-wave superfluid of dimers in dipolar 2D BF mixtures, conditions for stability of the mixture and study of universal properties of condensate; 3. Theoretical and experimental characterization of p-wave interactions between dimers and calculation of p-wave gap.
Results achieved
: Within DiQuT, the UNIBO unit focused on (i) the competition between pairing and condensation in 2D Bose–Fermi mixtures with tunable BF interaction, and (ii) the mechanical stability of Bose–Fermi mixtures in 3D and 2D. The first topic addressed the interplay between boson condensation and the formation of weakly bound boson–fermion dimers, relevant for p-wave pairing. This investigation was carried out during the first half of the project and led to: (1) J. D’Alberto et al., Phys. Rev. A 109, 053302 (2024). (2) L. Pisani et al., SciPost Phys. 18, 076 (2025). In (1), the unit derived leading beyond-mean-field contributions to the zero-temperature equation of state and to fermionic quasiparticle properties in 2D, benchmarking also against QMC results in the repulsive case and identifying deviations close to mechanical instability. In (2), a diagrammatic T-matrix approach showed that increasing BF attraction depletes the condensate while BF pairs form, with nearly universal behavior for isotopic mixtures relevant to Dysprosium. During the second half of the project, the unit investigated stability conditions of resonant BF mixtures, leading to: (3) C. Gualerzi et al., SciPost Phys. 19, 039 (2025). (4) P. Cordioli et al., arXiv:2602.15598 (submitted). These works quantify the minimal BB repulsion required to maintain stability across coupling regimes (3D) and extend the analysis to 2D (4), highlighting enhanced stability for isotopic mixtures such as Dysprosium. On the experimental side (CNR unit), while the realization of a robust degenerate dipolar Bose–Fermi mixture suitable for the planned measurements was not fully reached within the available resources and timeframe, the project enabled the development of a new and highly relevant experimental avenue based on Rydberg excitation and spectroscopy in dysprosium, providing an alternative long-range interacting platform compatible with both tweezer-array (discrete) and continuous geometries. This outcome maintains strong alignment with DiQuT’s long-term goals and supports future experimental investigations of topological models. Finally, the POLITO unit worked on the characterization and design of topological states of matter in systems with dipolar interactions. Two main directions were pursued: (i) topological properties of dipolar fermionic systems, and (ii) engineering of effective geometrical frustration and characterization of related phenomena. For direction (i), the unit investigated one-dimensional fermionic systems as a benchmark toward two-dimensional settings, demonstrating that dipolar interactions can stabilize quantized transport and proposing platforms based on Dysprosium or Erbium mixtures linking topology and superconductivity. It also explored two-dimensional bosonic systems with strong long-range repulsion, identifying a higher-order topological insulator. For direction (ii), the unit developed several schemes to induce geometrical frustration (dressed-state square ladders, subwavelength lattices, and anti-magic wavelength lattices with nonlocal interactions. These platforms enabled the study of chiral superfluidity, deconfined quantum criticality, and flux-induced magnetism/supersolidity.Project details
Unibo Team Leader: Pierbiagio Pieri
Unibo involved Department/s:
Dipartimento di Fisica e Astronomia "Augusto Righi"
Coordinator:
CNR - Consiglio Nazionale delle Ricerche(Italy)
Total Unibo Contribution: Euro (EUR) 65.271,00
Project Duration in months: 24
Start Date:
28/09/2023
End Date:
28/02/2026
