Publications Roberto TRICARICO

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)].

Preprint

• L. Bombieri, Z. Zeng, R. Tricarico, R. Lin, S. Notarnicola, M. Cain, M. Lukin, H. Pichler Quantum adiabatic optimization with Rydberg arrays: localization phenomena and encoding strategies, (2024-11-07), arXiv:2411.04645 arXiv:2411.04645 (ID: 721280) Toggle Abstract
  We study the quantum dynamics of the encoding scheme proposed in [Nguyen et al., PRX Quantum 4, 010316 (2023)], which encodes optimization problems on graphs with arbitrary connectivity into Rydberg atom arrays. Here, a graph vertex is represented by a wire of atoms, and the (crossing) crossing-with-edge gadget is placed at the intersection of two wires to (de)couple their degrees of freedom and reproduce the graph connectivity. We consider the fundamental geometry of two vertex-wires intersecting via a single gadget and look at minimum gap scaling with system size along adiabatic protocols. We find that both polynomial and exponential scaling are possible and, by means of perturbation theory, we relate the exponential closing of the minimum gap to an unfavorable localization of the ground-state wavefunction. Then, on the QuEra Aquila neutral atom machine, we observe such localization and its effect on the success probability of finding the correct solution to the encoded optimization problem. Finally, we propose possible strategies to avoid this quantum bottleneck, leading to an exponential improvement in the adiabatic performance.