Research
My main research lines lie at the intersection of quantum optics, statistical mechanics and condensed matter, ... here some keywords! : polariton superfluids, topological lasers, 2D materials (like few-layer transition metal dichalchogenides), flat bands, polarons in interacting Fermi systems, Kardar-Parisi-Zhang universality in non-equilibrium quasi-condensates, microscopic theory of excitons.
I am a theoretical physicist, but have many collaborations with experimentalists working with polaritons, 2D materials and cold atoms. I also don't back off when it comes to using numerical methods such as ED, QMC, DMRG or GPE simulations.
See below for a more detailed description of a few main topics!
Polaron spectroscopy of many-body systems
Optical spectroscopy has proven a powerful tool to probe the state of transition metal dichalchogenide (TMD) few-layer heterostructures. This is because the resonantly injected exciton gets dressed by the excitations of the electronic system: an impurity dressed by the excitations of the many-body background is called a polaron. TMDs systems are also particular interesting because they can be tuned (p.e. by twisting two monolayers with respect to each other) in such a way to display moiré physics and can host strongly correlated phases. Moreover, polarons can also be investigated in ultracold atomic clouds, where it is possible to tune the impurity-atom binding energy via Feschbach resonances.
Studying polarons immersed in a many-body background is a formidable challenge, and only very few theoretical works are available. Recently, I have discussed polaron spectra for bilayer excitonic insulators [PRB 107 (15), 155303] and Fermi superfluids [PRB 107 (10), 104519] by means of a variational approach (Chevy ansatz) built on top of the BCS mean-field theory. Moreover, in [SciPost Phys. 16, 056] I have implemented an exact diagonalization approach to compute the polaron spectra of sevaral extended Fermi-Hubbard models, the scenarios considered including charge density waves, multiple Fermi seas and pair superfluids.
(left) Sketch of an intra-layer exciton used as a quantum impurity to probe an interlayer excitonic insulator.
(right) Exact diagonalization prediction for the polaron spectrum in an attractive Hubbard model.
Theory of the coherence of unconventional lasers (topological, flat band, 1D arrays)
Can topological robustness be lead to a new generation of lasers? It has been proposed that the amplification of the edge of a 2D topological insulator results in lasing on the edge of the system, showing resilience to disorder and allowing for robust mode locking. This is expected to help overcome a main shortcoming of semiconductor laser arrays.
During my PhD I have analyzed the coherence of a topolaser built from an Harper-Hofstatter insulator [PRX 10 (4), 041060]. This work was the first nonlinear and stochastic study of the performances of a topolaser, demonstrating its supremacy when disorder is present. This effort inspired a series of follow-ups concerning the influence of the Kardar-Parisi-Zhang nonlinearity on the linewidth of 1D lasers Phys. Rev. E 109 (1) 014104, the collective modes and stability of 2D topolasers with a reservoir of carriers [PRA 104 (5), 053516], the connection between the non-orthogonality of Bogoliubov modes and the laser linewidth (leading to the unification of the Henry and Petermann factors) [PRA 105 (2), 023527], and the investigation of the role of quantum geometry in flat band lasers [PRL 132 186902 (2024)].
Last but not least, I contributed to the experimental observation of Kardar-Parisi-Zhang scaling, a peculiar non-equilibrium universality class first introduced to describe the stochastic growth of interfaces, in an array of 1D polaritons [Nature 608 (7924), 687-691].
(left) Sketch of lasing on the edge mode of a topological insulator, from [Science 359, 6381 (2018)].
(right) Peculiar scaling of the linewidth with system size in 1D laser arrays. The square-root behavior is a consequence of the Kardar-Parisi-Zhang nonlinearity.