Publications Gabriele CALLIARI

2026

Preprint

• G. Calliari, C. Fromonteil, F. Cesa, T. Zache, P. M. Preiss, R. Ott, H. Pichler Programmable Fermionic Quantum Processors with Globally Controlled Lattices, (2026-04-14), arXiv:2604.13160 arXiv:2604.13160 (ID: 721673) Toggle Abstract
  We introduce a framework for realizing universal fermionic quantum processing with globally controlled itinerant fermionic particles. Our approach is tailored to the example of neutral atoms in optical lattices, but transposes to other setups with similar capabilities. We give constructive protocols to realize arbitrary fermionic processes, with time-dependent control over global parameters of the experimental setup, such as tunneling and interaction in a Fermi-Hubbard type model. We first prove the universality of our framework and then discuss implementation variants, such as hybrid analog-digital simulation of extended Fermi-Hubbard models, e.g., with long-range couplings.

2025

Articles

• L. Bombieri, T. Zache, G. Calliari, M. Lukin, H. Pichler, D. Gonzalez Cuadra Deconfined quantum criticality on a triangular Rydberg array, Phys. Rev. Lett. 135 233602 (2025-12-04), http://dx.doi.org/10.1103/4rg4-zbnn doi:10.1103/4rg4-zbnn (ID: 721492) Toggle Abstract
  Fluctuations can drive continuous phase transitions between two distinct ordered phases -- so-called Deconfined Quantum Critical points (DQCPs) -- which lie beyond the Landau-Ginzburg-Wilson paradigm. Despite several theoretical predictions over the past decades, experimental evidence of DQCPs remains elusive. We show that a DQCP can be explored in a system of Rydberg atoms arranged on a triangular lattice and coupled through van der Waals interactions. Specifically, we investigate the nature of the phase transition between two ordered phases at 1/3 and at 2/3 Rydberg excitation density, which were recently probed experimentally in [P. Scholl et al., Nature 595, 233 (2021)]. Using a field-theoretical analysis, we predict both the critical exponents for infinitely long cylinders of increasing circumference and the emergence of a conformal field theory near criticality showing an enlarged U(1) symmetry -- a signature of DQCPs -- and confirm these predictions numerically. Finally, we extend these results to ladder geometries and show how the emergent U(1) symmetry could be probed experimentally using finite tweezer arrays.
• G. Calliari, M. Di Liberto, H. Pichler, T. Zache Quantum simulating continuum field theories with large-spin lattice models, PRX Quantum 6 30304 (2025-07-09), http://dx.doi.org/10.1103/nt76-ttmj doi:10.1103/nt76-ttmj (ID: 721390) Toggle Abstract
  Simulating the real-time dynamics of quantum field theories (QFTs) is one of the most promising applications of quantum simulators. Regularizing a bosonic QFT for quantum simulation purposes typically involves a truncation in Hilbert space in addition to a discretization of space. Here, we discuss how to perform such a regularization of scalar QFTs using multi-level or qudit systems, and show that this enables quantitative predictions in the continuum limit by extrapolating results obtained for large-spin lattice models. With extensive matrix-product state simulations, we numerically demonstrate the sequence of extrapolations that leads to quantitative agreement of observables for the integrable sine-Gordon (sG) QFT. We further show how to prepare static and moving soliton excitations, and analyze their scattering dynamics, in agreement with a semi-classical model and analytical predictions. Finally, we illustrate how a non-integrable perturbation of the sG model gives rise to dynamics reminiscent of string breaking and plasma oscillations in gauge theories. Our methods are directly applicable in state-of-the-art analog quantum simulators, opening the door to implementing a wide variety of scalar field theories and tackling long-standing questions in non-equilibrium QFT like the fate of the false vacuum.

Preprint

• G. Calliari, R. Ott, H. Pichler, T. Zache Field digitization scaling in a Z symmetric model, (2025-07-30), arXiv:2507.22984 arXiv:2507.22984 (ID: 721491) Toggle Abstract
  The simulation of quantum field theories, both classical and quantum, requires regularization of infinitely many degrees of freedom. However, in the context of field digitization (FD) -- a truncation of the local fields to discrete values -- a comprehensive framework to obtain continuum results is currently missing. Here, we propose to analyze FD by interpreting the parameter as a coupling in the renormalization group (RG) sense. As a first example, we investigate the two-dimensional classical -state clock model as a Z FD of the -symmetric -model. Using effective field theory, we employ the RG to derive generalized scaling hypotheses involving the FD parameter , which allows us to relate data obtained for different -regularized models in a procedure that we term (FDS). Using numerical tensor-network calculations at finite bond dimension , we further uncover an unconventional universal crossover around a low-temperature phase transition induced by finite , demonstrating that FDS can be extended to describe the interplay of and . Finally, we analytically prove that our calculations for the 2D classical-statistical Z clock model are directly related to the quantum physics in the ground state of a (2+1)D Z lattice gauge theory which serves as a FD of compact quantum electrodynamics. Our study thus paves the way for applications of FDS to quantum simulations of more complex models in higher spatial dimensions, where it could serve as a tool to analyze the continuum limit of digitized quantum field theories.