arXiv subjects

Carlo Gabbanini

Publications and source records attributed to Carlo Gabbanini.

9 recordsLinked to original sources

arXiv2026

Single-fluid model for rotating annular supersolids and its experimental implications

The famous two-fluid model of finite-temperature superfluids has been recently extended to describe the mixed classical-superfluid dynamics of the newly discovered supersolid phase of matter. We show that for rigidly rotating supersolids one can derive a more appropriate single-fluid model, in which the seemingly classical and superfluid contributions to the motion emerge from a spatially varying phase of the global wavefunction. That allows to design experimental protocols to excite and detect the peculiar rotation dynamics of annular supersolids, including partially quantized supercurrents, in which each atom brings less than $\hbar$ unit of angular momentum. Our results are valid for a more general class of density-modulated superfluids.

cond-mat.quant-gas↗

arXiv2025

Multipassage Landau-Zener tunneling oscillations in transverse/longitudinal dual dressing of atomic qubits

We investigate the time evolution of a non-resonant dressed-atom qubit in an XZ original configuration. It is composed of two electromagnetic fields, one oscillating parallel and the other orthogonal to the quantisation magnetic static field. The experiments are performed in rubidium and caesium atomic magnetometers, confined in a magneto-optical trap and in a vapour cell, respectively. Static fields in the $\mu$T range and kHz oscillating fields with large Rabi frequencies are applied. This dual-dressing configuration is an extension of the Landau-Zener multipassage interferometry in the presence of an additional dressing field controlling the tunneling process by its amplitude and phase. Our measurement of the qubit coherence introduces additional features to the transition probability readout of standard interferometry. The coherence time evolution is characterized by oscillations at several frequencies, each of them produced by a different quantum contribution. Such frequency description introduces a new picture of the qubit multipassage evolution. Because the present low-frequency dressing operation does not fall within the standard Floquet engineering paradigm based on the high-frequency expansion, we develop an ad-hoc dressing perturbation treatment. Numerical simulations support the adiabatic and non-adiabatic qubit evolution.

quant-ph↗

arXiv2025

Blue repulsive potential for dysprosium Bose-Einstein condensates

Short-wavelength repulsive potentials for quantum gases allow to realize new systems and to study new phenomena. Here we report the realization of repulsive optical potentials for dysprosium atoms in the blue region of the spectrum, at wavelengths close to 400 nm. We employ a spectrallyfiltered diode laser system to measure both scalar and tensorial components of the polarizability of dysprosium, which we find in good agreement with the theoretical predictions. We demonstrate the implementation of potential strengths appropriate to manipulate Bose-Einstein condensates, with scattering-limited lifetimes exceeding one second. This type of optical potentials opens interesting directions for the study of dipolar superfluids and supersolids.

cond-mat.quant-gas↗

arXiv2025

Self-induced Josephson oscillations and self-trapping in a supersolid dipolar quantum gas

The Josephson effect characterizes superfluids and superconductors separated by a weak link, the so-called Josephson junction. A recent experiment has shown that Josephson oscillations can be observed also in a supersolid, where the weak link is not due to an external barrier, but is self-induced by interparticle interactions. Here we show theoretically that supersolids -- despite their self-induced character -- feature all the standard properties of bosonic Josephson junction arrays, including macroscopic quantum self-trapping. We focus on the harmonically trapped dipolar supersolids of interest for current experiments, and show that they can be described with a generalized Josephson model that takes into account spatial inhomogeneities. Our work shades new light on the dynamics of supersolids and opens the way to the study of a novel class of Josephson junctions.

cond-mat.quant-gas↗

arXiv2023

Sub-unity superfluid fraction of a supersolid from self-induced Josephson effect

Recently, a new category of superfluids and superconductors has been discovered in various systems. These could be linked to the idea of a supersolid phase, featuring a macroscopic wavefunction with spatial modulation resulting from simultaneous, spontaneous breaking of gauge and translational symmetries. However, this relation has only been recognized in some cases and there is the need for universal properties quantifying the differences between supersolids and ordinary superfluids/superconductors or crystals. A key property is the superfluid fraction, which measures the reduction in superfluid stiffness due to spatial modulation, leading to the non-standard superfluid dynamics of supersolids. Here we employ the Josephson effect, common in superfluids and superconductors, to measure the superfluid fraction in a supersolid. Even without a physical barrier, the Josephson effect arises spontaneously in a supersolid due to spatial modulation. Individual lattice cells act as self-induced Josephson junctions, allowing the direct determination of the local superfluid fraction. We studied a cold-atom dipolar supersolid, revealing a significant sub-unity superfluid fraction. Our results open new research directions, enabling the exploration of novel phenomena like partially quantized vortices and supercurrents, potentially unifying the understanding of supersolid-like systems, and introducing a new type of Josephson junction.

cond-mat.quant-gas↗

arXiv2020

Magnetic Induction Imaging with a cold-atom radio-frequency magnetometer

The sensitive detection of either static or radio-frequency \textsc{(rf)} magnetic fields is essential to many fundamental studies and applications. Here, we demonstrate the operation of a cold-atom-based, \textsc{rf} magnetometer in performing {1-D and 2-D imaging} of small metallic objects. It is based on a cold $^{85}$Rb atomic sample, and operates in an unshielded environment with no active field stabilization. It shows a sensitivity up to $200\, \rm{pT}/\sqrt{\rm Hz}$ in the $5-35\, \rm{kHz}$ range bandwidth and can resolve a cut $0.4\, \rm{mm}$ wide in a $0.8\, \rm{mm}$ thick metallic foil. The characteristics of our system make it a good candidate for applications in civil and industrial surveillance.

physics.atom-ph↗

arXiv2019

Observation of a dipolar quantum gas with metastable supersolid properties

The competition of dipole-dipole and contact interactions leads to exciting new physics in dipolar gases, well-illustrated by the recent observation of quantum droplets and rotons in dipolar condensates. We show that the combination of the roton instability and quantum stabilization leads under proper conditions to a novel regime that presents supersolid properties, due to the coexistence of stripe modulation and phase coherence. In a combined experimental and theoretical analysis, we determine the parameter regime for the formation of coherent stripes, whose lifetime of a few tens of milliseconds is limited by the eventual destruction of the stripe pattern due to three-body losses. Our results open intriguing prospects for the development of long-lived dipolar supersolids.

cond-mat.quant-gas↗

arXiv2010

Photoionization spectroscopy of excited states of cold cesium dimers

Photoionization spectroscopy of cold cesium dimers obtained by photoassociation of cold atoms in a magneto-optical trap is reported here. In particular, we report on the observation and on the spectroscopic analysis of all the excited states that have actually been used for efficient detection of cold molecules stabilized in the triplet a^3Sigma_u^+ ground state. They are: the (1)^3Sigma_g^+ state connected to the 6s+6p asymptote, the (2)^3Sigma_g^+ and (2)^3Pi_g states connected to the 6s+5d asymptote and finally the (3)^3Sigma_g^+ state connected to the 6s + 7s asymptote. The detection through these states spans a wide range of laser energies, from 8000 to 16500 cm-1, obtained with different laser dyes and techniques. Information on the initial distribution of cold molecules among the different vibrational levels of the a^3Sigma_u^+ ground state is also provided. This spectroscopic knowledge is important when conceiving schemes for quantum manipulation, population transfer and optical detection of cold cesium molecules.

physics.chem-ph↗

arXiv2009

Formation and interactions of cold and ultracold molecules: new challenges for interdisciplinary physics

Progress on researches in the field of molecules at cold and ultracold temperatures is reported in this review. It covers extensively the experimental methods to produce, detect and characterize cold and ultracold molecules including association of ultracold atoms, deceleration by external fields and kinematic cooling. Confinement of molecules in different kinds of traps is also discussed. The basic theoretical issues related to the knowledge of the molecular structure, the atom-molecule and molecule-molecule mutual interactions, and to their possible manipulation and control with external fields, are reviewed. A short discussion on the broad area of applications completes the review.

quant-ph↗