2025/12/27 by Rafi Weill, Weill, Rafi, Jonathan Nemirovsky +3
Physics and Astronomy · Computer Science · #Cold Atom Physics and Bose-Einstein Condensates #Quantum Information and Cryptography #Quantum and electron transport phenomena
paper · doi:10.48550/arxiv.2512.22569
Collisional gates in optical superlattices have recently achieved record fidelities, but their operation times are typically limited by tunneling. Here we propose and analyze an alternative route to a fast √(SWAP) gate for two fermionic atoms in an optical superlattice based on optimized, time-dependent control of the short and long lattice depths. The gate is implemented by transiently releasing the atoms into a quasi-harmonic confinement centered between the two sites. With an appropriately chosen contact interaction strength, a controlled collision accumulates the exchange phase required for √(SWAP) and generates entanglement. We employ a continuum, time-dependent Schrödinger-equation simulation that goes beyond a two-site Fermi--Hubbard description and benchmark it against experimentally implemented tunneling-based protocols, reproducing the observed single-particle tunneling and spin-exchange dynamics. For experimentally accessible lattice depths, we find that the proposed gate operates in ∼ 21 μs, more than an order of magnitude faster than tunneling-based implementations, while achieving fidelities \gtrsim 99%. We further analyze sensitivity to lattice-depth variations and show that a composite sequence improves robustness. Our results establish fast, collision-mediated entangling gates in superlattices as a promising building block for scalable neutral-atom quantum computation.