Publications Francesco CESA

2026

Preprints

• F. Cesa, A. Di Fini, D. A. Korbany, R. Tricarico, H. Bernien, H. Pichler, L. Piroli Engineering discrete local dynamics in globally driven dual-species atom arrays, (2026-01-23), arXiv:2601.16961 arXiv:2601.16961 (ID: 721660) Toggle Abstract
  We introduce a method for engineering discrete local dynamics in globally-driven dual-species neutral atom experiments, allowing us to study emergent digital models through uniform analog controls. Leveraging the new opportunities offered by dual-species systems, such as species-alternated driving, our construction exploits simple Floquet protocols on static atom arrangements, and benefits of generalized blockade regimes (different inter- and intra-species interactions). We focus on discrete dynamical models that are special examples of Quantum Cellular Automata (QCA), and explicitly consider a number of relevant examples, including the kicked-Ising model, the Floquet Kitaev honeycomb model, and the digitization of generic translation-invariant nearest-neighbor Hamiltonians (e.g., for Trotterized evolution). As an application, we study chaotic features of discretized many-body dynamics that can be detected by leveraging only demonstrated capabilities of globally-driven experiments, and benchmark their ability to discriminate chaotic evolution.
• R. White, V. Ramesh, A. Impertro, S. Anand, F. Cesa, G. Giudici, T. Iadecola, H. Pichler, H. Bernien Quantum Cellular Automata on a Dual-Species Rydberg Processor, (2026-01-22), arXiv:2601.16257 arXiv:2601.16257 (ID: 721659) Toggle Abstract
  As quantum devices scale to larger and larger sizes, a significant challenge emerges in scaling their coherent controls accordingly. Quantum cellular automata (QCAs) constitute a promising framework that bypasses this control problem: universal dynamics can be achieved using only a static qubit array and global control operations. We realize QCAs on a dual-species Rydberg array of rubidium and cesium atoms, leveraging independent global control of each species to perform a myriad of quantum protocols. With simple pulse sequences, we explore many-body dynamics and generate a variety of entangled states, including GHZ states, 96.7(1.7)\\%-fidelity Bell states, 17-qubit cluster states, and high-connectivity graph states. The versatility and scalability of QCAs offers compelling routes for scaling quantum information systems with global controls, as well as new perspectives on quantum many-body dynamics.

2025

Preprint

• F. Cesa, H. Bernien, H. Pichler Fast and Error-Correctable Quantum RAM, (2025-03-24), arXiv:2503.19172v1 arXiv:2503.19172v1 (ID: 721473) Toggle Abstract
  Quantum devices can process data in a fundamentally different way than classical computers. To leverage this potential, many algorithms require the aid of a quantum Random Access Memory (QRAM), i.e. a module capable of efficiently loading datasets (both classical and quantum) onto the quantum processor. However, a realization of this fundamental building block is still outstanding, since existing proposals require prohibitively many resources for reliable implementations, or are not compatible with current architectures. Moreover, present approaches cannot be scaled-up, as they do not allow for efficient quantum error-correction. Here we develop a QRAM design, that enables fast and robust QRAM calls, naturally allows for fault-tolerant and error-corrected operation, and can be integrated on present hardware. Our proposal employs a special quantum resource state that is consumed during the QRAM call: we discuss how it can be assembled and processed efficiently in a dedicated module, and give detailed blueprints for modern neutral-atom processors. Our work places a long missing, fundamental component of quantum computers within reach of currently available technology; this opens the door to algorithms featuring practical quantum advantage, including search or oracular problems, quantum chemistry and machine learning.

2024

Article

• C. Fromonteil, R. Tricarico, F. Cesa, H. Pichler Hamilton-Jacobi-Bellman equations for Rydberg-blockade processes, Phys. Rev. Research 6 33333 (2024-09-24), http://dx.doi.org/10.1103/PhysRevResearch.6.033333 doi:10.1103/PhysRevResearch.6.033333 (ID: 721246) Toggle Abstract
  We discuss time-optimal control problems for two setups involving globally driven Rydberg atoms in the blockade limit by deriving the associated Hamilton-Jacobi-Bellman equations. From these equations, we extract the globally optimal trajectories and the corresponding controls for several target processes of the atomic system, using a generalized method of characteristics. We apply this method to retrieve known results for CZ and C-phase gates, and to find new optimal pulses for all elementary processes involved in the universal quantum computation scheme introduced in [Physical Review Letters 131, 170601 (2023)].

2023

Article

• F. Cesa, H. Pichler Universal Quantum Computation in Globally Driven Rydberg Atom Arrays, Phys. Rev. Lett. 131 170601 (2023-10-24), http://dx.doi.org/10.1103/PhysRevLett.131.170601 doi:10.1103/PhysRevLett.131.170601 (ID: 721145) Toggle Abstract
  We develop a model for quantum computation with Rydberg atom arrays, which only relies on global driving, without the need of local addressing of the qubits: any circuit is executed by a sequence of global, resonant laser pulses on a static atomic arrangement. We present two constructions: for the first, the circuit is imprinted in the trap positions of the atoms and executed by the pulses; for the second, the atom arrangement is circuit-independent, and the algorithm is entirely encoded in the global driving sequence. Our results show in particular that a quadratic overhead in atom number is sufficient to eliminate the need for local control to realize a universal quantum processor. We give explicit protocols for all steps of an arbitrary quantum computation, and discuss strategies for error suppression specific to our model. Our scheme is based on dual-species processors with atoms subjected to Rydberg blockade constraints, but it might be transposed to other setups as well.