Continuous operation of a coherent 3,000-qubit system
N.-C. Chiu, Elias C. Trapp, Jinen Guo, M. H. Abobeih, Luke M. Stewart, Simon Hollerith, P. Stroganov, Marcin Kalinowski, Alexandra A. Geim, Simon J. Evered, Sophie H. Li, Xingjian Lyu, Lisa M. Peters, Dolev Bluvstein, Tout T. Wang, Markus Greiner, Vladan Vuletić, Mikhail D. Lukin
Neutral atoms are a promising platform for quantum science, enabling advances in areas ranging from quantum simulations 1−3 and computation 4−10 to metrology, atomic clocks 11−13 and quantum networking 14−16 . While atom losses typically limit these systems to a pulsed mode, continuous operation 17−22 could significantly enhance cycle rates, remove bottlenecks in metrology 23 , and enable deep-circuit quantum evolution through quantum error correction 24,25 . Here we demonstrate an experimental architecture for high-rate reloading and continuous operation of a large-scale atom array system while realizing coherent storage and manipulation of quantum information. Our approach utilizes a series of two optical lattice conveyor belts to transport atom reservoirs into the science region, where atoms are repeatedly extracted into optical tweezers without affecting the coherence of qubits stored nearby. Using a reloading rate of 300,000 atoms in tweezers per second, we create over 30,000 initialized qubits per second, which we leverage to assemble and maintain an array of over 3,000 atoms for more than two hours. Furthermore, we demonstrate persistent refilling of the array with atomic qubits in either a spin-polarized or a coherent superposition state while preserving the quantum state of stored qubits. Our results pave the way for realization of large-scale continuously operated atomic clocks, sensors, and fault-tolerant quantum computers.
Neutral atoms are a promising platform for quantum science, enabling advances in areas ranging from quantum simulations 1−3 and computation 4−10 to metrology, atomic clocks 11−13 and quantum networking 14−16 . While atom losses typically limit these systems to a pulsed mode, continuous operation 17−22 could significantly enhance cycle rates, remove bottlenecks in metrology 23 , and enable deep-circuit quantum evolution through quantum error correction 24,25 . Here we demonstrate an experimental architecture for high-rate reloading and continuous operation of a large-scale atom array system while realizing coherent storage and manipulation of quantum information. Our approach utilizes a series of two optical lattice conveyor belts to transport atom reservoirs into the science region, where atoms are repeatedly extracted into optical tweezers without affecting the coherence of qubits stored nearby. Using a reloading rate of 300,000 atoms in tweezers per second, we create over 30,000 initialized qubits per second, which we leverage to assemble and maintain an array of over 3,000 atoms for more than two hours. Furthermore, we demonstrate persistent refilling of the array with atomic qubits in either a spin-polarized or a coherent superposition state while preserving the quantum state of stored qubits. Our results pave the way for realization of large-scale continuously operated atomic clocks, sensors, and fault-tolerant quantum computers.
Scaling the size of assembled neutral-atom arrays trapped in optical lattices or optical tweezers is an enabling step for a number of applications ranging from quantum simulations to quantum metrology. However, preparation times increase with system size and constitute a severe bottleneck in the bottom-up assembly of large ordered arrays from stochastically loaded optical traps. Here we demonstrate a method to circumvent this bottleneck by recycling atoms from one experimental run to the next, while continuously reloading and adding atoms to the array. Using this approach, we achieve densely packed arrays with more than 1000 atoms stored in an optical lattice, continuously refilled with a 3.5 s cycle time and about 130 atoms reloaded during each cycle. Furthermore, we show that we can continuously maintain such large arrays by simply reloading atoms that are lost from one cycle to the next. Our approach paves the way towards quantum science with large ordered atomic arrays containing thousands of atoms in continuous operation. Published by the American Physical Society 2024
Neutral-atom quantum processors are a promising platform for scalable quantum computing. An obstacle to implementing deep quantum circuits is managing atom loss. Current approaches require at least an order of magnitude longer time than gate and measurement operations to replace lost atoms. In this work, we demonstrate fast, continuous atom reloading that leverages the metastable 171 Yb qubit. A continuously loaded reservoir near the computation zone enables on-demand atom extraction with tweezers up to 500 times per second. New, stochastically filled qubit arrays can be initialized 30 times per second when including single-atom preparation, nondestructive imaging, and initialization. Existing qubits in the metastable state are undisturbed by the reloading process. This work establishes a complete foundation for the implementation of fast, fully fault-tolerant quantum circuits with unlimited depth.
Optical tweezer arrays 1,2 have transformed atomic and molecular physics, now forming the backbone for a range of leading experiments in quantum computing 3–8 , simulation 1,9–12 , and metrology 13–15 . Typical experiments trap tens to hundreds of atomic qubits, and recently systems with around one thousand atoms were realized without defining qubits or demonstrating coherent control 16–18 . However, scaling to thousands of atomic qubits with long coherence times, low-loss, and high-fidelity imaging is an outstanding challenge and critical for progress in quantum science, particularly towards quantum error correction 19,20 . Here, we experimentally realize an array of optical tweezers trapping over 6,100 neutral atoms in around 12,000 sites, simultaneously surpassing state-of-the-art performance for several metrics that underpin the success of the platform. Specifically, while scaling to such a large number of atoms, we demonstrate a coherence time of 12.6(1) seconds, a record for hyperfine qubits in an optical tweezer array. We show room-temperature trapping lifetimes of ~ 23 minutes, enabling record-high imaging survival of 99.98952(1)% with an imaging fidelity of over 99.99%. We present a plan for zone-based quantum computing 5,21 and demonstrate necessary coherence-preserving qubit transport and pick-up/drop-off operations on large spatial scales, characterized through interleaved randomized benchmarking. Our results, along with recent developments 8,22–24 , indicate that universal quantum computing and quantum error correction with thousands to tens of thousands of physical qubits could be a near-term prospect.
Neutral atom arrays have emerged as a leading platform for scalable quantum information processing, offering reconfigurable geometry, strong interactions, and high-fidelity control. While encoding quantum information in atomic qubits provides multiple natural advantages, information can be lost through mechanisms such as atom loss, depolarization, and decoherence, necessitating the need for quantum error correction. However, the processes underlying error correction, including measurement and gate operations, can themselves induce atom loss, ultimately limiting the achievable computational circuit depth. This thesis presents the design and realization of a large-scale neutral atom array quantum architecture capable of continuous coherent operation. By replenishing fresh atomic qubits during operation, the system solves a key bottleneck to scalability in space and time. We further show that, through careful system design, quantum coherence can be preserved while introducing new atoms and initializing them as qubits. We discuss the architectural and physical considerations underlying this approach and demonstrate a platform comprising more than 3,000 reconfigurable qubits. These results establish a pathway toward persistent quantum operation and have broad implications for quantum computing, quantum simulation, and quantum metrology.
Optical tweezer arrays of neutral atoms have been demonstrated in recent years to be a useful platform for quantum simulation, computation, and metrology. Realizing the full potential of these applications requires increasing qubit numbers while simultaneously maintaining high-fidelity control, which has proved a major challenge across quantum platforms. To date, quantum science experiments have typically been operated with at most hundreds of qubits. In this thesis, we review the relevant physics of the optical tweezer array architecture and present the technical advances involved in scaling the platform to 6,100 atomic qubits. In tandem with scalability, we demonstrate robust vacuum design, state-of-the-art coherence times, and high single-qubit gate fidelities. To capitalize on the intrinsic connectivity of the architecture at large scale, we investigate long-distance coherent atom transport and briefly describe progress towards two-qubit gate implementation. Finally, we discuss the prospects for scaling the optical tweezer array platform further by an order of magnitude.
Assembling and maintaining large arrays of individually addressable atoms is a key requirement for continued scaling of neutral-atom-based quantum computers and simulators. In this work, we demonstrate a new paradigm for assembly of atomic arrays, based on a synergistic combination of optical tweezers and cavity-enhanced optical lattices, and the incremental filling of a target array from a repetitively filled reservoir. In this protocol, the tweezers provide microscopic rearrangement of atoms, while the cavity-enhanced lattices enable the creation of large numbers of optical traps with sufficient depth for rapid low-loss imaging of atoms. We apply this protocol to demonstrate near-deterministic filling (99% per-site occupancy) of 1225-site arrays of optical traps. Because the reservoir is repeatedly filled with fresh atoms, the array can be maintained in a filled state indefinitely. We anticipate that this protocol will be compatible with mid-circuit reloading of atoms into a quantum processor, which will be a key capability for running large-scale error-corrected quantum computations whose durations exceed the lifetime of a single atom in the system. Published by the American Physical Society 2024