33 research outputs found
Multicomponent spin mixtures of two-electron fermions
These lecture notes contain an introduction to the physics of quantum
mixtures of ultracold atoms trapped in multiple internal states. I will discuss
the case of fermionic isotopes of alkaline-earth atoms, which feature an
intrinsic SU() interaction symmetry and convenient methods for the optical
manipulation of their nuclear spin. Some research directions will be presented,
with focus on experiments performed in Florence with nuclear-spin mixtures of
Yb atoms in optical lattices.Comment: 33 pages, 13 figures, Lecture notes for the Proceedings of the
International School of Physics "Enrico Fermi" Course 211 "Quantum Mixtures
with Ultra-Cold Atoms" (Varenna, Italy, 2022
Multi-colored liquids of fermions
Un esperimento realizzato nei laboratori del Dipartimento di Fisica e Astronomia dell’Università di Firenze ha messo in evidenza il comportamento di fermioni fortemente interagenti in una dimensione. Controllando il numero di stati interni in un gas di atomi ultrafreddi, si è osservata per la prima volta la transizione da un comportamento fermionico a un comportamento bosonico, in accordo con recenti previsioni teoriche.An experiment performed in the labs of the Department of Physics and Astronomy of the University of Florence has demonstrated the behavior of strongly-interacting one-dimensional fermions. By controlling the number of internal states in a gas of ultracold atoms, we have observed for the first time the crossover from fermionic to bosonic behavior, in agreement with recent theoretical predictions
Enabling Inverse Design in Chemical Compound Space: Mapping Quantum Properties to Structures for Small Organic Molecules
Computer-driven molecular design combines the principles of chemistry,
physics, and artificial intelligence to identify novel chemical compounds and
materials with desired properties for a specific application. In particular,
quantum-mechanical (QM) methods combined with machine learning (ML) techniques
have accelerated the estimation of accurate molecular properties, providing a
direct mapping from 3D molecular structures to their properties. However, the
development of reliable and efficient methodologies to enable \emph{inverse
mapping} in chemical space is a long-standing challenge that has not been
accomplished yet. Here, we address this challenge by demonstrating the
possibility of parametrizing a given chemical space with a finite set of
extensive and intensive QM properties. In doing so, we develop a
proof-of-concept implementation that combines a Variational Auto-Encoder (VAE)
trained on molecular structures with a property encoder designed to learn the
latent representation from a set of QM properties. The result of this joint
architecture is a common latent space representation for both structures and
properties, which enables property-to-structure mapping for small drug-like
molecules contained in the QM7-X dataset. We illustrate the capabilities of our
approach by conditional generation of \emph{de novo} molecular structures with
targeted properties, transition path interpolation for chemical reactions as
well as insights into property-structure relationships. Our findings thus
provide a proof-of-principle demonstration aiming to enable the inverse
property-to-structure design in diverse chemical spaces.Comment: 17 pages, 8 figures, 1 tabl
A compact ultranarrow high-power laser system for experiments with 578nm Ytterbium clock transition
In this paper we present the realization of a compact, high-power laser
system able to excite the Ytterbium clock transition at 578 nm. Starting from
an external-cavity laser based on a quantum dot chip at 1156 nm with an
intra-cavity electro-optic modulator, we were able to obtain up to 60 mW of
visible light at 578 nm via frequency doubling. The laser is locked with a 500
kHz bandwidth to a ultra-low-expansion glass cavity stabilized at its zero
coefficient of thermal expansion temperature through an original thermal
insulation and correction system. This laser allowed the observation of the
clock transition in fermionic Yb with a < 50 Hz linewidth over 5
minutes, limited only by a residual frequency drift of some 0.1 Hz/s
A Bose-Einstein condensate in an optical lattice with tunable spacing: transport and static properties
In this Letter we report the investigation of transport and static properties
of a Bose-Einstein condensate in a large-spaced optical lattice. The lattice
spacing can be easily tuned starting from few micrometers by adjusting the
relative angle of two partially reflective mirrors. We have performed in-situ
imaging of the atoms trapped in the potential wells of a 20 micrometers-spaced
lattice. For a lattice spacing of 10 micrometers we have studied the transport
properties of the system and the interference pattern after expansion,
evidencing quite different results with respect to the physics of BECs in
ordinary near-infrared standing wave lattices, owing to the different length
and energy scales.Comment: 11 pages, 7 figures, revised version (modified figures, extended
text
Enhancement of chiral edge currents in (+1)-dimensional atomic Mott-band hybrid insulators
We consider the effect of a local interatomic repulsion on synthetic
heterostructures where a discrete synthetic dimension is created by Raman
processes on top of -symmetric two-dimensional lattice systems. At a
filling of one fermion per site, increasing the interaction strength, the
system is driven towards a Mott state which is adiabatically connected to a
band insulator. The chiral currents associated with the synthetic magnetic
field increase all the way to the Mott transition, where they reach the maximum
value, and they remain finite in the whole insulating state. The transition
towards the Mott-band insulator is associated with the opening of a gap within
the low-energy quasiparticle peak, while a mean-field picture is recovered deep
in the insulating state.Comment: 27 Pages, 10 Figure
Quasiparticle dynamics in a Bose insulator probed by inter-band Bragg spectroscopy
We investigate experimentally and theoretically the dynamical properties of a
Mott insulator in decoupled one-dimensional chains. Using a theoretical
analysis of the Bragg excitation scheme we show that the spectrum of inter-band
transitions holds information on the single-particle Green's function of the
insulator. In particular the existence of particle-hole coherence due to
quantum fluctuations in the Mott state is clearly seen in the Bragg spectra and
quantified. Finally we propose a scheme to directly measure the full, momentum
resolved spectral function as obtained in angle-resolved photoemission
spectroscopy of solids.Comment: The new version contains improved theoretical treatment and data
analysi