My broad research field: Theory of Many-Body Quantum Systems
As of 2023, my current research interests are
* Topological phenomena in condensed-matter and cold-atoms setups
* Out-of-equilibrium physics in closed and open quantum systems
The birth of quantum mechanics: Fraunhofer's black lines. I love this picture. Atomic spectra (that is what Fraunhofer first measured with astonishing precision) are what physicists tried to model when laying the foundations of quantum mechanics. I like to think that what we are doing now traces its origins back over 200 years to an optics laboratory nestled within the secularized Benedictine monastery of Benediktbeuern..
An emergent behavior of a physical system is a qualitative property that can only occur in the limit that the number of microscopic constituents tends to infinity.
We are all familiar with the fundamental concepts of quantum mechanics and how to employ them to describe a hydrogen atom.
What is left to do is to theoretically understand the emerging properties of systems composed of a large number of elementary quantum systems, like a gas or a magnet. This is precisely the focus of investigation within my research group.
Below, you will find a brief overview of some of my recent research interests. Internships and research projects are often available for any of the topics mentioned.
The fractional quantum Hall effect gained worldwide fame also because it describes an electron liquid that hosts emerging quasiparticles excitations that have (i) a charge that is a fraction of the electron's charge and (ii) a fractional statistics that is neither bosonic nor fermionic.
In a series of recent studies we have explored the characterisation of a third fractional property: the spin! These quasiparticles indeed appear to satisfy a generalised spin-statistics relation, all while possessing a measurable spin!
Want to know more? Check out our research articles or simply get in touch with us. I am currently working on this with Alberto Nardin - alberto DOT nardin AT universite-paris-saclay DOT fr
A. Nardin and L. Mazza, Laughlin's quasielectron is a non-local composite fermion, arXiv:2306.13972 (2023)
A. Nardin, E. Ardonne, L. Mazza, Spin-statistics relation for quantum Hall states, Phys. Rev. B 108 L041105 (2023) - Editors' Suggestion - pdf - arXiv
T. Comparin, A. Opler, E. Macaluso, A. Biella, A. P. Polychronakos, L. Mazza, A measurable fractional spin for quantum Hall quasiparticles on the disk, Phys. Rev. B 105 085125 (2022) - pdf - arXiv
E. Macaluso, T. Comparin, L. Mazza, I. Carusotto, Fusion channels of non-Abelian anyons from angular-momentum and density-profile measurements, Phys. Rev. Lett. 123, 266801 (2019) - pdf - arXiv
Following the establishment of statistical physics, significant effort has been devoted to link the temporal dynamical properties of a system to the emergence of equilibrium and thermodynamics. The eigenstate thermalisation hypothesis, proposed in the early 1990's by Mark Srednicki, stands as a cornerstone in this endeavour. According to the ETH, in a generic quantum many-body system the energy eigenstates are characterised by a unique quantum number: their energy density. This hypothesis wields a significant explicative power and accounts for the thermalisation process in the majority of studied quantum systems.
However, an hypothesis is just an hypothesis, and the realm of reality encompasses a far broader range of phenomena. Recent years have witnessed substantial investigation into quantum many-body scars—exact eigenstates that do not obey to ETH. One of the distinguishing features of these scar states is that when chosen as initial states of a dynamical evolution, they lead to a non-ergodic evolution, resulting in a perpetual lack of thermalisation.
In our research activity we are interested in such anomalous non-thermalising dynamics, albeit from a different perspective. We do not want to look for exact anomalous eigenstates: we want to find anomalous initial states among the set of states that are always assume to thermalise. Does it sound counterintuitive? We already have an example: asymptotic quantum many-body scars! And we think that more will follow.
Want to know more? Check out our research articles or simply get in touch with us. I am currently working on this with Maurizio Fagotti and Gianluca Morettini.
L. Gotta, S. Moudgalya, L. Mazza, Asymptotic Quantum Many-Body Scars, arXiv:2303.05407 (2023)
Could you think of something more boring than losses that plague all experiments with ultra-cold gases? That's what I always thought... before I delved into this subject myself. Ultra-cold gases are typically confined within electromagnetic traps, yet a small number of atoms or molecules always manage to escape, eventually leading to the complete depletion of the setup.
The truth is, losses can be a remarkably economic source of fascinating physics for two main reasons:
i) they can drive the gas through non-equilibrium states of matter and create novel phases of matter;
ii) they can fail to completely deplete the gas and create stationary states with non-trivial properties, e.g. many-body entanglement.
In a series of recent works we are exploring the properties of a bosonic or fermionic quantum gas subjected to two-body losses.
Want to know more? Check out our research articles or simply get in touch with us. I have supervised the Ph.D. thesis of Lorenzo Rosso on this topic and I recently got fundings from ANR and CNRS for collaborating with the experimentalists in Villetaneause (Martin Robert-De-Saint-Vincent, Benjamin Pasquiou and Bruno Laburthe-Tolra) and theorists in Tokyo (Hosho Katsura and Hironobu Yoshida). I am currently working on this with Alice Marché - alice DOT marche AT universite-paris-saclay DOT fr
L. Rosso, A. Biella, J. De Nardis, L. Mazza, A dynamical theory for one-dimensional fermions with strong two-body losses: universal non-Hermitian Zeno physics and spin-charge separation, Phys. Rev. A 107 013303 (2023) - pdf - arXiv
L. Rosso, L. Mazza, A. Biella, Eightfold way to dark states in SU(3) cold gases with two-body losses, Phys. Rev. A 105 L051302 (2022) - pdf - arXiv
L. Rosso, A. Biella and L. Mazza, The one-dimensional Bose gas with strong two-body losses: the effect of the harmonic confinement, SciPost Phys. 12, 044 (2022) - pdf - arXiv
L. Rosso, D. Rossini, A. Biella and L. Mazza, One-dimensional spin-1/2 fermionic gases with two-body losses: weak dissipation and spin conservation, Phys. Rev. A 104 053305 (2021) - pdf - arXiv
D. Rossini, A. Ghermaoui, M. Bosch Aguilera, R. Vatré, R. Bouganne, J. Beugnon, F. Gerbier and L. Mazza, Strong correlations in lossy one-dimensional quantum gases: from the quantum Zeno effect to the generalised Gibbs ensemble, Phys. Rev. A 103, L060201 (2021) - pdf - arXiv