Quantum computers hold a promise to solve certain problems that are intractable to classical computers, offering a paradigm shift in fields ranging from cryptography to materials science. However, realizing this potential requires overcoming the challenge of scalability, which encompasses both spatial scalability – the capacity for large qubit registers, and temporal scalability – the capability to execute deep quantum circuits. This thesis describes the construction and experimental characterization of a new rubidium atom array quantum platform, which advances the scalability frontier of atomic quantum processors in both spatial and temporal domains. The platform achieves a record-scale ∼ 99%-filling-fraction array with more than 3,000 qubits, and is shown to operate continuously for more than 2 hours. These advances are enabled by a novel architecture that supports high-flux refilling of atomic qubits without decohering neighboring sites. Combined with other recent progress demonstrated in the field of neutral atom quantum information processing, this platform provides a viable pathway toward large-scale, fault-tolerant quantum processing capable of executing deep error-corrected circuits.
Quantum computers hold a promise to solve certain problems that are intractable to classical computers, offering a paradigm shift in fields ranging from cryptography to materials science. However, realizing this potential requires overcoming the challenge of scalability, which encompasses both spatial scalability – the capacity for large qubit registers, and temporal scalability – the capability to execute deep quantum circuits. This thesis describes the construction and experimental characterization of a new rubidium atom array quantum platform, which advances the scalability frontier of atomic quantum processors in both spatial and temporal domains. The platform achieves a record-scale ∼ 99%-filling-fraction array with more than 3,000 qubits, and is shown to operate continuously for more than 2 hours. These advances are enabled by a novel architecture that supports high-flux refilling of atomic qubits without decohering neighboring sites. Combined with other recent progress demonstrated in the field of neutral atom quantum information processing, this platform provides a viable pathway toward large-scale, fault-tolerant quantum processing capable of executing deep error-corrected circuits.
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.
Quantum computers open new scientific avenues, from exploring complex quantum mechanical systems to new computational paradigms, but face the fundamental challenge of decoherence. Remarkably, decoherence can be prevented by creating highly entangled states of physical qubits that encode an error-corrected “logical” qubit. This thesis will describe the development of quantum computing with reconfigurable arrays of neutral atoms and their use for quantum processing with logical qubits. Quantum processing in this approach is based on the coherent transport of atoms shuttled by optical tweezers, enabling any-to-any connectivity, high-fidelity programmable logic, and mid-circuit processing within a zoned architecture. Logical qubit processing is greatly facilitated by parallel control and transversal operations, and is used for experiments ranging from entangling logical qubits to their use for precise simulation of quantum scrambling. Core physical mechanisms for achieving deep-circuit, universal algorithms with logical qubits are identified, and these are leveraged into new techniques that greatly reduce overheads for large-scale computation. Finally, applications of quantum processors will be explored via analog and gate-based quantum simulations. These results, alongside other recent advances, herald a transition to error-corrected quantum processing, establishing foundations that can enable future large-scale quantum computers and their useful applications.
Quantum processors have the potential to significantly advance our understanding of quantum systems. In particular, the programmability of digital quantum devices enables access to highly tunable quantum dynamics and observables. The central challenge, however, is suppressing errors, making quantum error correction essential for large-scale algorithms. In this thesis, I present work on quantum processing with reconfigurable atom arrays, with experiments featuring up to 448 neutral atom qubits, high two-qubit gate fidelities, arbitrary connectivity, and mid-circuit qubit readout and reuse. Using this system, I describe how we realize gate-based quantum simulations. In particular, we experimentally study Kitaev’s honeycomb model and explore hardware-efficient fermion-to-qubit encodings. We then leverage unique opportunities with atoms to study the key building blocks of scalable quantum error correction. These include below-threshold performance, deep computation at constant entropy, and universal logical gates. Together, these experiments highlight unique near-term opportunities with atom arrays and chart a path toward future large-scale atomic processors.
Neutral-atom arrays are a leading platform for quantum technologies, offering a promising route toward large-scale, fault-tolerant quantum computing. We propose a novel quantum processing architecture based on dual-type, dual-element atom arrays, where individually trapped atoms serve as data qubits, and small atomic ensembles enable ancillary operations. By leveraging the selective initialization, coherent control, and collective optical response of atomic ensembles, we demonstrate ensemble-assisted quantum operations that enable reconfigurable, high-speed control of individual data qubits and rapid mid-circuit readout, including both projective single-qubit and joint multi-qubit measurements. The hybrid approach of this architecture combines the long coherence times of single-atom qubits with the enhanced controllability of atomic ensembles, achieving high-fidelity state manipulation and detection with minimal crosstalk. Numerical simulations indicate that our scheme supports individually addressable single- and multi-qubit operations with fidelities of 99.5% and 99.9%, respectively, as well as fast single- and multi-qubit state readout with fidelities exceeding 99% within tens of microseconds. These capabilities open new pathways toward scalable, fault-tolerant quantum computation, enabling repetitive error syndrome detection and efficient generation of long-range entangled many-body states, thereby expanding the quantum information toolbox beyond existing platforms.
Neutral atom arrays have rapidly emerged as a leading platform for quantum computing, boasting scalable, configurable arrays of single atoms trapped in optical tweezers, fast, high-fidelity entangling gates through Rydberg interactions, and programmable, parallelized control of qubit operations. Coupling an atom array to an optical cavity opens a new frontier. Leveraging enhanced light-atom interactions in cavity quantum electrodynamics, cavity- coupled atom arrays acquire capabilities that can further expand the neutral atom toolbox, including cavity-enhanced atom readouts, atom-photon entanglement, and photon-mediated interactions between distant atoms. This thesis presents a quantum hardware platform that integrates an array of neutral atoms with a high-finesse optical cavity. After describing the design and development of the experimental apparatus, I demonstrate high-fidelity atom state readout through the cavity, achieving improved speed and atom survival compared to conventional free-space imaging methods. I then introduce a new technique for selectively controlling atom-cavity coupling on arbitrary subsets of the array, using local AC Stark shifts on the excited states of the atoms. Building on these tools, I demonstrate fast, non-destructive cavity-based readout of atom arrays, a crucial bottleneck of atom array platforms. I also showcase real-time measurement and feedback capabilities with a demonstration of classical error correction, using a register of atomic bits. Finally, I describe progress toward implementing single- and two-qubit gates within the cavity-coupled system. By combining coherent control, tunable interactions, and high-fidelity, non-destructive readout integrated and real-time feedback, the cavity-coupled Rydberg atom array offers a promising path toward fault-tolerant quantum computing.
Quantum computers have the potential to solve certain problems exponentially faster than classical computers. However, realizing this potential in practice is a major challenge, as it requires precise control over large-scale quantum systems operating at extremely low error rates. Quantum error correction (QEC) provides a path to achieving such error rates, but its substantial resource overhead poses a significant practical barrier. In addition, identifying which computational problems offer a provable quantum advantage—and which remain fundamentally intractable—remains an open question. This thesis presents progress towards addressing both of these challenges. The first part of this thesis describes advances that substantially reduce the resource overhead of QEC. We begin by presenting realizations of logical circuits in dynamically reconfigurable arrays of neutral atoms. By jointly decoding the logical qubits, we reduce the cost of implementing such transversal Clifford circuits by a factor proportional to the code distance. We then develop new theories of fault tolerance to extend these savings to universal quantum computation with magic state inputs. Finally, we introduce techniques for fast correlated decoding, enabling practical implementations of these improvements in experimental hardware. Collectively, these advances accelerate progress toward large-scale computation and reduce the cost of QEC by over an order of magnitude. The second part of the thesis explores the relative power of quantum and classical computation in combinatorial optimization, a class of problems that is ubiquitous in science and engineering and foundational to the theory of computational complexity. We experimentally implement the optimized quantum adiabatic algorithm (QAA) in neutral atom arrays and observe evidence of a superlinear speedup over classical simulated annealing on certain hard problem instances. To interpret these results, we develop a theoretical framework to compare the performance of QAA with a broad class of classical Markov chain Monte Carlo algorithms. We identify conditions under which a quantum quadratic speedup is achievable and propose modifications to the QAA to reliably realize this advantage. Together, these contributions advance both the practical implementation and theoretical understanding of quantum algorithms.