Optimized Readout Strategies Achieve High-Fidelity Quantum Processing with Neutral Atoms

Neutral atom processors represent a significant advance in scalable quantum computing, promising both high-fidelity operations and the potential for large numbers of qubits. Liang Chen, Wen-Yi Zhu, and Zi-Jie Chen, alongside their colleagues at the Key Laboratory of Quantum Information, University of Science and Technology of China, address a critical bottleneck in this emerging field: the efficient and accurate extraction of readout results. Their research introduces a theoretical framework to balance readout fidelity with the retention of atomic state, a crucial consideration for maintaining system performance. By developing a new metric, the circuit iteration rate (qCIR), and utilising normalised Fisher information, the team demonstrates a readout strategy capable of optimising information acquisition, achieving qCIRs of up to 197.2Hz with currently available technology. This work offers practical guidance for building scalable neutral atom processors suitable for applications ranging from precision sensing to the implementation of near-term quantum algorithms.

A significant hurdle in translating this potential into practical applications lies in efficiently extracting readout outcomes while simultaneously maintaining a high system throughput, the rate at which quantum tasks can be completed. This work addresses this challenge by developing a comprehensive theoretical framework to precisely quantify the inherent trade-off between readout fidelity and the retention of atoms within the processor. The research introduces a novel metric, the quantum circuit iteration rate (qCIR), alongside the use of normalized Fisher information, to comprehensively characterize overall system performance.

Scientists demonstrate a readout strategy meticulously designed to optimize information acquisition efficiency by carefully balancing the competing demands of fidelity and atomic retention. Through detailed analysis, the team establishes that, considering experimentally feasible parameters for 87Rb atoms, qCIRs of 197.2Hz are achievable when utilizing single photon detectors. Alternatively, employing cameras for detection allows for qCIRs of 154.5Hz, demonstrating viable high-throughput operation. These results provide crucial practical guidance for the construction of scalable and high-throughput neutral atom processors, paving the way for advancements in diverse fields.

The study unveils a systematic investigation into the readout process, focusing on the relationship between optical readout fidelity and the probability of retaining atoms during measurement. Researchers analyze how critical experimental parameters, including the number of scattered photons, trap depth, collection efficiency, and experimental cycle times, directly influence overall system throughput. By leveraging normalized Fisher information as a benchmark, the work establishes a clear understanding of performance limitations and opportunities for optimization. Experiments show that the ability to prepare large-scale quantum systems with over 6,000 neutral atoms, exhibiting coherence times exceeding 12.6 seconds, surpasses the performance of many solid-state quantum platforms.

However, traditional readout methods disrupt the atomic array, necessitating complete re-preparation before each task iteration. This research establishes a pathway to mitigate this limitation, offering a means to enhance throughput and unlock the full potential of neutral atom quantum processors for applications in sensing, simulation, and the implementation of near-term quantum algorithms. The work opens new avenues for developing non-destructive readout techniques and optimizing experimental parameters for maximum efficiency.

Readout Optimisation and System Performance Metrics

Neutral atom processors represent a rapidly developing platform for scalable quantum information processing, distinguished by high-fidelity operations and exceptional qubit scalability. This work addresses a critical challenge, efficiently extracting readout outcomes while maintaining high system throughput, and introduces a theoretical framework to quantify the trade-off between readout fidelity and atomic retention. Scientists developed a new metric, the quantum circuit iteration rate (qCIR), alongside the use of normalized Fisher information, to comprehensively characterize overall system performance. Through careful balancing of fidelity and retention, the research team demonstrated a readout strategy designed to optimize information acquisition efficiency.

Experiments, conducted using experimentally feasible parameters for 87Rb atoms, revealed that qCIRs of 197.2Hz are achievable when employing single photon detectors. Furthermore, the team measured a qCIR of 154.5Hz using camera-based detection systems, demonstrating significant potential for rapid task execution. These measurements confirm the feasibility of high-throughput operation, crucial for complex quantum algorithms and sensing applications. The study meticulously analyzed the photon scattering process during readout, recognizing that increased photon scattering enhances fidelity but simultaneously elevates atomic heating and the risk of atom loss from optical traps.

Researchers systematically investigated the relationship between readout fidelity and atomic retention probability, identifying key experimental parameters influencing performance. The work highlights the importance of trap depth, collection efficiency, and readout duration in optimizing the readout process. Data shows that achieving both high readout fidelity and atom retention exceeding 99% for a single atom is possible without the need for optical cavities, paving the way for faster and more efficient quantum processors. This breakthrough delivers practical guidance for constructing scalable neutral atom processors applicable to diverse fields including advanced sensing technologies, complex simulations, and the implementation of near-term quantum algorithms.

The study details how a non-destructive readout technique, preserving atoms in the trap with high retention probability, enables immediate execution of subsequent circuit iterations. This approach circumvents the significant overhead associated with complete array re-preparation, a limitation of traditional neutral atom systems. Measurements confirm that by optimizing controllable variables, including re-preparation duration, cycle time, trap depth, and atomic scattering rate, scientists can maximize qCIR and overall system performance. The research provides a comprehensive understanding of the interplay between physical processes and informatics processing, offering a pathway towards realizing the full potential of neutral atom quantum platforms.