ATom Arrays with Resonant dipolAr eXchange InterActions

Project Information

ATARAXIA

Grant agreement ID: 101018511

DOI

10.3030/101018511

EC signature date 7 June 2021

Start date 1 January 2022

End date 31 December 2027

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 2 426 455,00

EU contribution

€ 2 426 455,00

Coordinated by

CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS
France

Periodic Reporting for period 2 - ATARAXIA (ATom Arrays with Resonant dipolAr eXchange InterActions)

Reporting period: 2023-07-01 to 2024-12-31

Summary of the context and overall objectives of the project

This project will study out-of-equilibrium dynamics of isolated and dissipative quantum systems, and interacting topological matter using a new type of synthetic many-body system pioneered in my group: assembled arrays of individual laser-cooled atoms held in microscopic optical traps.
Unlike most traditional approaches exploiting van der Waals interactions, here the atoms will be coupled by resonant dipole interactions, a new opportunity that we introduced recently. This interaction naturally realizes a spin model where the spin excitations behave as particles hopping between sites and strongly interact with each other. The unique feature of this interaction is that it allows for the exploration of many-body problems both in a unitary regime where the interactions are fully conservative, and in a regime with collective dissipation by the emission of light. We will investigate these two situations using two different setups. The unitary regime will rely on an existing platform where rubidium atoms are excited to Rydberg states to implement large interactions. The dissipative regime will be explored on a new apparatus specifically built for the study of controlled, collective dissipation. It will be based on arrays of individual dysprosium atoms coupled by resonant interactions on an optical transition.
These interactions, combined with our ability to vary the geometry of the arrays, to perform high-fidelity manipulations of individual atoms and measure correlation functions, will allow us to address open questions, in collaboration with theorists. We will (i) investigate out-of-equilibrium quantum magnetism in spin systems, in particular with frustrated geometries; (ii) seek to obtain the first realization of a bosonic fractional topological insulator; (iii) prepare collective states with tailored coupling to light, study the emergence of quantum correlations in a dissipative regime, and generate a new kind of interaction-induced single-photon non-linearity.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

In the first 30 months of the project, we have obtained several major results on the three objectives of the project:
O1 – Out-of-equilibrium quantum dynamics in arrays of Rydberg atoms
• Demonstration of a new way to generate extended spin models by Floquet engineering with microwaves [Phys. Rev. X Quantum 2022]
• Observation of Long-Range Order in a 2-dimensional XY magnets [Nature 2023]
• Demonstration of scalable spin squeezing with dipolar interaction [Nature 2023]
• Demonstration of a quench spectroscopy method to measure the dispersion relation of a dipolar quantum magnets, and observation of the anomalous behavior for the ferromagnetic coupling due the dipolar tail of the interaction [under review at Science 2024].
• Demonstration of local manipulation and readout in arrays of interacting Rydberg atoms, and demonstration of an elementary brick of a chiral spin liquid using a 6 atom setting (measurement of chiral-chiral correlations), [Phys. Rev. Lett. 2024].
• Theoretical proposal for the measurement of entanglement entropy between interacting Rydberg atoms by applying local random unitary operations.

O2 – Towards bosonic topological insulator in 2D arrays of Rydberg atoms
Theoretical investigation of experimentally realizable interacting topological phases, in collaboration with H-P Büchler [Phys. Rev. X Quantum 2022] and M. Fleischhauer [New. Journal of Physics 2022]. These lay the ground for an experimental realization, although challenging under the current protocols.
O3 – Subradiance and correlations in arrays with collective dissipation
• Observation of a non-equilibrium phase transition on our dense atomic cloud setup [Nature Physics 2023]
• Theoretical investigation of the non-equilibrium phase transition observed above jointly with the group of A-M Rey in JILA (USA) [under review PRXQ 2024] and D. Chang (ICFO, Spain) [under review PRXQ 2024].
• Experimental demonstration that the light emitted by a driven dissipative elongated cloud features non-gaussian correlations, a pre-requisite to utilize the for quantum information tasks [Phys. Rev. Lett. 2024]
• Trapping of individual Dysprosium atoms in optical tweezers on our new experiments [Phys. Rev. Lett. 2023]
• Measurement of various polarizabilities (scalar, vectorial and tensorial) of Dy atoms in a 532-nm optical tweezer [arXiv 2024, under review at Phys. Rev. A].

In parallel to these works, we explored in collaboration with theorists several questions related to many-body physics, that either used the data produced on our experiments or proposed new experimental methods:

• New protocol to generate enlarged classes of spin Hamiltonians using Floquet engineering [Phys. Rev. A 2023]
• Wavefunction network description of a many-body system, and benchmark on data from our implementation of the quantum Ising model in 2021 [PRX 2024]
• Exploration of a spin-slave boson method to solve the Fermi Hubbard model on a Rydberg quantum simulation [PRB 2024].

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

We will (i) investigate out-of-equilibrium quantum magnetism in spin systems, in particular with frustrated geometries; (ii) seek to obtain the first realization of a bosonic fractional topological insulator; (iii) prepare collective states with tailored coupling to light, study the emergence of quantum correlations in a dissipative regime, and generate a new kind of interaction-induced single-photon non-linearity.

Arrays of individual atoms in various geometry