Ultracold atoms in optical lattices are a popular platform in quantum science for both studies of quantum simulation and quantum metrology. Alkaline-earth atoms like strontium offer many opportunities, such as a large-spin fermions with SU(N) symmetry as well as narrow or ultranarrow transitions. In particular, strontium-87 presents a nuclear spin of I = 9/2 with no electronic spin in its...
Fermionic atoms in optical lattices enable the study of strongly-correlated electronic systems in regimes that are numerically inaccessible to classical methods [1]. Traditionally, these quantum simulators are operated in an analogue mode to either emulate the dynamics under their native Fermi-Hubbard Hamiltonian, or to approximate its ground state adiabatically [2,3]. However, challenges such...
One of the key driving forces in the investigation of quantum computing is the search for quantum advantage in real-world applications.[1] These include the simulation of properties and the determination of ground-state energies in many-body systems relevant to material science, quantum chemistry, and particle physics.[2] Given the fermionic nature of the said tasks, qubit-based simulators...
Excitons (coupled electron–hole pairs) in semiconductors can form collective states that sometimes exhibit spectacular nonlinear properties. Here, we show experimental evidence of a collective state of short-lived excitons in a direct-bandgap, atomically thin MoS2 semiconductor whose propagation resembles that of a classical liquid as suggested by the nearly uniform photoluminescence through...
A novel methodology that leverages physics-informed neural networks to optimize quantum circuits in systems with N_Q qubits by addressing the counterdiabatic (CD) protocol is introduced. The primary purpose is to employ physics-inspired deep learning techniques for accurately modeling the time evolution of various physical observables within quantum systems. To achieve this, we integrate...
Gauge theories provide an accurate description of fundamental interactions, as both perturbation theory and quantum Monte Carlo computations in lattice gauge theory, when applicable, show remarkable agreement with experimental data from particle colliders and cosmological observations. Complementing these computations, or combining them with quantum-inspired Hamiltonian lattice computations on...
We propose a magnetostirring protocol to create persistent currents on an annular system. Under this protocol, polar bosons confined in a three-well ring circuit reach a state with high average circulation. We model the system with an extended Bose-Hubbard Hamiltonian and show that the protocol can create circulation in an atomtronic circuit for a range of tunable parameters. The performance...
Spin-orbit-coupled Bose-Einstein condensates are a flexible experimental platform to engineer synthetic quantum many-body systems. In particular, they host the so-called stripe phase, an instance of a supersolid state of matter. The peculiar excitation spectrum of the stripe phase, a definite footprint of its supersolidity, has so far remained out of experimental reach. We achieve in situ...
Dipolar Bose-Einstein condensates are excellent platforms for studying supersolidity, characterized by coexisting density modulation and superfluidity. The realization of dipolar mixtures opens intriguing new scenarios, most remarkably the possibility of realizing a double supersolid, composed by two interacting superfluids. We analyze the complex excitation spectrum of a miscible trapped...
Topological gauge theories provide an explanation of strongly correlated materials through a weakly-interacting picture.
In this talk, I will discuss an experimental scheme to realize with ultracold atoms a one-dimensional instance of these theories, known as the Chiral BF theory, in a ring geometry. I will first introduce the underlying principles of these theories, and examine them in the...
Excited-state quantum phase transitions (ESQPTs) generalize the concept of quantum phase transitions to include transitions occurring at finite energies, beyond the ground state. These transitions can be induced not only by varying a control parameter but also by changing the energy of the system. In this work, we explore ESQPTs in spinor Bose-Einstein condensates, highlighting their...
Cold atomic ensembles are good candidates for quantum nodes serving as quantum memories, deterministic photon sources, and processing units. I will present the latest results obtained in this context, featuring the generation of indistinguishable photons from independent cold atomic ensembles nodes, and the cavity enhanced generation of non-classical light.
Local Hamiltonians, H_{k}, describe non-trivial k-body interactions in quantum many-body systems. In this work, we address the dynamical simulatability of a k-local Hamiltonian by a simpler one, H_{k’}, with k’ < k. First, we work on the Hilbert space that both Hamiltonians act on. When it comes to exact simulation, we build upon methods to derive examples of H_{k} and H_{k’} that simulate the...
The reason why mitigations techniques such as dynamical decoupling success or fail in different quantum technological scenarios is not fully understood. The random telegraph noise (RTN) model is often used to describe coherent noise, which is a semiclassical model. In this work we introduce a full quantum model to describe coherent noise on a qubit, where the qubit is coupled to a two level...
Spontaneously symmetry-broken (SSB) phases are locally ordered states of matter characterizing a large variety of physical systems. Because of their specific ordering, their presence is usually witnessed by means of local order parameters. Here, we propose an alternative approach based on statistical correlations of noise after the ballistic expansion of an atomic cloud. We indeed demonstrate...
"We propose a 1D anyon Hubbard model as the foundation for the Pauli Engine, a quantum heat engine rooted in the Pauli exclusion principle. Unlike traditional heat engines, this engine operates cyclically and can perform work even without a thermal bath, driven purely by quantum many-body interactions and anyonic statistics.
Our study explores how the statistical parameter and Hubbard...
Trapped-ion systems offer exceptional platforms for investigating topological phase transitions and detecting ultra-weak forces, owing to the high degree of control over their vibrational degrees of freedom. We theoretically simulate topological driven-dissipative phases in a one-dimensional chain consisting of approximately 20–30 sites. The emergence of topological phases, characterized by a...
"Anomalous diffusion (AD) describes transport phenomena where the mean-square displacement (MSD) of a particle does not scale linearly with time, deviating from classical diffusion. This behavior, often linked to non-equilibrium phenomena, sheds light on the underlying mechanisms in various systems, including biological and financial domains.
Integrating insights from anomalous diffusion...
In recent years, machine learning models, chiefly deep neural networks, have revealed suited to learn accurate energy-density functionals from data. However, problematic instabilities have been shown to occur in the search of ground-state density profiles via energy minimization. Indeed, any small noise can lead astray from realistic profiles, causing the failure of the learned functional and,...
"Shortcuts to Adiabaticity (STA) enable fast generation of states typically obtained through slow adiabatic processes. We explore the creation of Bell states in multi-component ultra-cold atomic gases using controllable inter-particle interactions via Feshbach resonances. Extending previous work, we demonstrate the feasibility of accessing the symmetric Bell states $|\psi_+\rangle =...
We study the dynamical manifestation of the chaotic phase in the time-dependent propagation of experimentally relevant two-particle correlations for one-dimensional interacting bosons by means of a conveniently defined two-particle correlation transport distance l. Our results show that the chaotic phase induces the emergence of an effective diffusive regime in the asymptotic temporal growth...
"We provide a scalable, resource efficient scheme for the quantum simulation and computation of Abelian lattice gauge theories (LGTs) with continuous gauge groups in the Hamiltonian formulation. We study compact quantum electrodynamics (cQED) in two spatial dimensions, formulated in terms of rotors and strings as introduced in [1]. We complement this formulation with a recent technique for the...
We study one-dimensional systems of one or two atoms (bosons, fermions, or distinguishable) interacting via contact delta-like interactions with one or more delta potential barriers. They are assumed to be confined either in parabolic or square well potentials. We show that these systems offer a perfect playground to study the interplay between integrability or quantum chaos, discrete...
"An important and widely used tool in quantum metrology is the spin squeezing parameter. Its development was mainly motivated by two applications: the improvement of precision measurements beyond the classical limit and the study of particle correlations and entanglement [1]. In quantum metrology, the spin squeezing parameter determines the sensitivity that can be achieved through the...
The combination of quantum-gas microscopy with alkaline-earth atoms offers many exciting prospects for quantum simulation of Hubbard models.
In this contribution, we present the latest results on quantum-gas microscopy from the Strontium Lab at ICFO. In a first set of experiments, we worked with the bosonic isotope 84Sr. We routinely prepared Bose-Einstein condensates of 84Sr, load them in...
Currently, most optimization algorithms for updating the parameters of variational circuits rely on the gradient descent algorithm. Recently, a modification of this algorithm was proposed to include information about the geometry of the quantum state, known as Quantum Natural Gradient. This method involves using the Quantum Fisher Information Matrix, which can be obtained by taking the real...
"Fermi-Landau liquid theory breaks down in case of one-dimensional interacting fermion systems. Instead a framework of Tomonaga-Luttinger liquid theory can be applied, limited to lowest-energy excitations with strictly linear dispersion around Fermi energy.
Here I present the theory of strongly correlated one-dimensional systems of fermions, or bosons, applicable for excitation energies (or...
We predict that ultracold bosonic dipolar gases, confined within a multilayer geometry, may undergo self-assembling processes, leading to the formation of chain gases and solids. These dipolar chains, with dipoles aligned across different layers, emerge at low densities and resemble phases observed in liquid crystals, such as nematic and smectic phases. We calculate the phase diagram using...
"We propose an experimental implementation of a scheme proposed by Goncalves et al. [1], to produce unusual and tunable photon correlations by interfering resonance fluorescence from a single atom with probe light from a weak laser beam. A number of interesting and potentially useful features are predicted by Goncalves et al., including (under different conditions of pump-probe relative phase...
Quantum reservoir computing (QRC) exploits the dynamical properties of quantum systems to perform machine learning tasks. We demonstrate that optimal performance in QRC can be achieved without relying on disordered systems. Systems with all-to-all topologies and random couplings are generally considered to minimize redundancies and enhance performance. In contrast, our work investigates the...
Ion-trapped Quantum Charge-Coupled Device (QCCD) architectures have emerged as a promising alternative to scale single-trap devices by interconnecting multiple traps through ion shuttling, enabling the execution of parallel operations across different traps. While this parallelism enhances computational throughput, it introduces additional operations, raising the following question: do the...
A two-dimensional spin-up ideal Fermi gas interacting attractively with a spin-down impurity in the continuum undergoes, at zero temperature, a first-order phase transition from a polaron to a dimeron state. Here we study a similar system on a square lattice, by considering the attractive 2D Fermi-Hubbard model with a single spin-down and a finite filling fraction of spin-up fermions. We study...
We present a thorough study of the transition nature of Fermi gases. The exploration can be done thanks to the use of a third order perturbation formula for the energy system. At this level, there are three scattering parameters in play, those are, the S-wave scattering length 𝑎0, the S-wave effective range r0 and the P -wave scattering length a1. We show that the spin value is not determinant...
"In this work, we are developing a cold strontium-88 platform based on arrays of Rydberg atoms trapped in optical tweezers to perform simulations of lattice gauge theories.
In this poster, we present the progress towards the construction of the apparatus. In particular, we report on the status of the vacuum environment of the experiment and the laser cooling and trapping system that will...
Characterizing the non-classical correlations of a complex many-body system is an important part of quantum technologies. A versatile tool for such a task is one that scales well with the size of the system and which can be both easily computed and measured. In this work we focus on graph states, that are promising platforms for quantum computation, simulation and metrology. We consider four...
Quantum computing is a promising technology that faces several challenges. Among these limitations, high physical error rates are a significant hurdle to overcome. The limited number of physical qubits in current quantum devices is an obstacle to implementing quantum error correction techniques. However, despite this limitation, it may be possible to address the impact of errors by employing...
It has been shown that dipolar Bose-Einstein condensates that are tightly trapped along the polarization direction can feature a rich phase diagram. In this paper we show that finite temperature can assist in accessing parts of the phase diagram that otherwise appear hard to realise due to excessively large densities and number of atoms being required. These include honeycomb and stripe phases...
Decoherence (dissipation and dephasing) is usually considered detrimental in quantum information and quantum optics applications. However, the interplay between environment dynamics and unitary evolution can give rise to interesting quantum many-body phenomena and can even be harnessed to become a useful resource.
As it is well known, in dense atomic arrays coupled to a common radiation...
Due to quantum degeneracy and extraordinarily low inelastic collision rates, a 87Rb BEC is, relative to its volume, the most sensitive magnetometer ever demonstrated, with combined spatial, temporal, and field resolution beyond what is possible with existing sensing approaches. Extreme magnetic sensitivity on small length scales enables searches for short-range spin-dependent forces that may...
Topological systems, a remarkable topic in condensed matter physics, have been implemented in different platforms like ultracold atoms in optical lattices and photonic systems. The properties of single-particle topological systems have been extensively studied, but there is still much to learn about many-body systems. Two-body systems, in which tightly-bound pairs of interacting particles...
We demonstrate that spinor Bose-Einstein condensates (BEC) can be operated as an analog simulator of the two-dimensional vibron model. This algebraic model for the description of bending and streching vibrations of molecules, in the case of a triatomic molecules, exhibits two phases where linear and bent configurations are stabilised. Spinor BECs can be engineered to simulate states that...
We study symmetry-breaking in spontaneous Floquet states, focusing on atomic condensates. First, we quantize the Nambu-Goldstone (NG) modes for stationary states spontaneously breaking several symmetries by invoking the generalized Gibbs ensemble. The quantization involves a Berry-Gibbs connection, which depends on the macroscopic conserved charges and whose curvature is not invariant under...
We introduce a novel experimental protocol to measure generalized temporal entropies in many-body quantum systems. Our approach involves using local operators as probes to observe out-of-equilibrium dynamics of a replicated system induced by a double quench. We compare the dynamics induced by the quench in the intergable transverse field Ising model and the non-integrable transverse field...
We study dynamical localization [1, 2] in an ultracold atom confined in an optical lattice that is simultaneously shaken by two competing pulsatile modulations with different amplitudes, periods, and waveforms. The effects of finite-width time pulses, modulation waveforms, and commensurable and incommensurable driving periods_x000D_
are investigated. We describe a particularly complex...
We analyze the propagation of experimentally relevant two-particle correlations for one-dimensional interacting bosons, and give evidence that many-body chaos induces the emergence of an effective diffusive regime for the fully coherent correlation dynamics, characterized by an interaction dependent diffusion coefficient, which we estimate. This result supports very recent experimental...
Ultracold atoms held in optical lattice potentials have emerged as promising candidates for quantum simulators and quantum computation. In particular, Floquet engineering, manipulating the system's properties by applying a periodic driving, plays a crucial role in generating artificial gauge fields and exotic topological phases. However, driving-induced heating and the growth of phonon modes...
The superfluid fraction f of a quantum fluid is defined in terms of the response of the system to a weak and constant drag. Notably, Leggett long ago derived two simple expressions providing a rigorous upper bound and a heuristic lower bound for f. Here we study the superfluid fraction of bosonic gases in various two-dimensional potentials, such as regular optical lattices and disordered...
Modern quantum engineering techniques allow the synthesis of quantum systems in exotic geometries, including fractal lattices characterized by a self-similar pattern and fractal dimensions, or hyperbolic lattices characterized by negative curvature. These geometries can significantly modify single and many-body quantum behavior. We focus on the properties of Bose-Einstein condensation in such...
Although condensed matter systems have been extensively studied in one- and two-dimensional configurations, the impact of spatial confinement beyond mere dimensionality has received comparatively little attention. Interestingly, research into quantum systems with curved geometries has gained significant momentum over the past decade. In the field of ultracold atoms [1], recent experiments were...
We study the thermal behavior of correlations in a one-dimensional Bose gas with tunable interaction strength, crossing from weakly-repulsive to Tonks-Girardeau regime [1-2]. A reference temperature in this system is that of the hole anomaly [3], observed as a peak in the specific heat and a maximum in the chemical potential. At the anomaly temperature, the spectral states located below the...
