Abstract
Rydberg atom arrays are a leading platform for quantum computing and simulation, combining strong interactions with highly coherent operations and flexible geometries. However, the achievable fidelities are limited by the finite lifetime of the Rydberg states, as well as technical imperfections such as atomic motion. In this work, we propose a novel approach to Rydberg atom arrays using long-lived circular Rydberg states in optical traps. Based on the extremely long lifetime of these states, exceeding seconds in cryogenic microwave cavities that suppress radiative transitions, and gate protocols that are robust to finite atomic temperature, we project that arrays of hundreds of circular Rydberg atoms with two-qubit gate errors around $10^{-5}$ can be realized using current technology. This approach combines several key elements, including a quantum nondemolition detection technique for circular Rydberg states, local manipulation using the ponderomotive potential of focused optical beams, a gate protocol using multiple circular levels to encode qubits, and robust dynamical decoupling sequences to suppress unwanted interactions and errors from atomic motion. This represents a significant improvement on the current state-of-the-art in quantum computing and simulation with neutral atoms.
Highlights
Rydberg-atom arrays are a leading platform for quantum computing and simulation, combining strong interactions with highly coherent operations and flexible geometries
We describe a technique for local manipulation using the ponderomotive potential of focused Laguerre-Gauss (LG) beams, enabling siteaddressed manipulation of the atoms between the circular Rydberg states used to encode the qubit
We propose an architecture for a quantum computer based on individually trapped and manipulated circular Rydberg atoms
Summary
(i) Initialize ground-state arrays (ii) Excite circular atoms (iii) Verify circular excitation (c). The compute and ancilla arrays are initialized with single ground-state atoms using rearrangement-based techniques [23,24,25]. The compute array is excited into |1a using a combination of laser excitation and rf rapid adiabatic passage [31] Since this excitation is challenging to realize with extremely high fidelity because of quantum speed limits associated with the dense spectrum of Rydberg states [32], the ancilla array is used to nondestructively measure which atoms have been correctly excited, and a second rearrangement is performed to fill in a small number of defects in the circular atom array. The atoms left behind in the storage states (with the dynamical decoupling sequence continuously applied) are unaffected by the measurement, allowing partial readout of the qubit array
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