A compact ion-trap quantum computing demonstrator (2101.11390v3)

Abstract: Quantum information processing is steadily progressing from a purely academic discipline towards applications throughout science and industry. Transitioning from lab-based, proof-of-concept experiments to robust, integrated realizations of quantum information processing hardware is an important step in this process. However, the nature of traditional laboratory setups does not offer itself readily to scaling up system sizes or allow for applications outside of laboratory-grade environments. This transition requires overcoming challenges in engineering and integration without sacrificing the state-of-the-art performance of laboratory implementations. Here, we present a 19-inch rack quantum computing demonstrator based on $^{40}\textrm{Ca}^+$ optical qubits in a linear Paul trap to address many of these challenges. We outline the mechanical, optical, and electrical subsystems. Further, we describe the automation and remote access components of the quantum computing stack. We conclude by describing characterization measurements relevant to digital quantum computing including entangling operations mediated by the Molmer-Sorenson interaction. Using this setup we produce maximally-entangled Greenberger-Horne-Zeilinger states with up to 24 ions without the use of post-selection or error mitigation techniques; on par with well-established conventional laboratory setups.

• The paper demonstrates a modular ion-trap quantum computing system that integrates 40 optical qubits in a 19-inch rack, marking a significant step towards scalability.
• It details innovative mechanical, optical, and electrical subsystems that enable precise qubit control and stable operation using commercially available diode lasers.
• Experimental results include generating Greenberger-Horne-Zeilinger states with up to 24 ions, indicating the setup's potential for practical quantum applications.

Summary of "A Compact Ion-Trap Quantum Computing Demonstrator"

The paper "A Compact Ion-Trap Quantum Computing Demonstrator" details a significant step towards creating scalable, integrated quantum computing systems utilizing trapped ion architectures. Recognizing the advancements in quantum information processing, the paper articulates a design that transitions away from traditional laboratory setups to a modular system housed in a standard 19-inch rack. This innovation aims to address scalability and integration challenges without compromising on performance metrics obtained in conventional laboratory environments.

Central to this endeavor is the ion-trap quantum computing demonstrator that integrates 40 optical qubits in a linear Paul trap. Key elements of the demonstrator are its mechanical, optical, and electrical subsystems, designed to ensure the adaptability and robustness required for scaling quantum systems. The system features accessible automation and remote user operation, pushing the boundaries towards practical applications of quantum computing in diverse environments.

The ion qubit system incorporates optical qubits encoded within calcium-40 ions, leveraging the advantages of natural optical transitions to simplify the experimental setup. In doing so, it eschews the complexity associated with Raman transitions for different qubit types, while taking advantage of commercially available diode lasers for essential operations like addressing, entanglement generation, and readout detection.

Experimentally, the platform is characterized by achievements such as the successful preparation of Greenberger-Horne-Zeilinger states with up to 24 ions without error mitigation, on par with traditional setups. This is complemented by the demonstrator's use of a scalable modular optical setup that allows for individual or collective ion addressing through microoptics and acousto-optic deflectors, essential for universal quantum computation.

The paper provides extensive technical detail concerning the subsystems and their interconnectivity. Noteworthy is the integration across two 19-inch racks featuring components for optical frequency generation, remote operation, vibration isolation, and precise environmental control, aimed at overcoming the challenges of qubit manipulation and control fidelity outside specialized lab settings. Key mechanical advancements include a rigidly-constructed and vibration-isolated housing, capable of stable temperature and magnetic field conditions conducive for quantum operations.

The implications of this research stretch beyond immediate technical feasibility. The demonstrator sets a precedence in the modularization and operational independence of quantum computing systems from large laboratory confines, facilitating the development of quantum processors capable of operating in broader industrial and scientific environments. Such systems, by being more accessible and user-friendly, could expedite the integration of quantum processing into real-world applications, thereby catalyzing progress in various computational fields.

Looking ahead, further hardware enhancements, such as the transition to an internal laser system and continued improvement of qubit coherence time and entangling operations, are anticipated. These developments will further bolster the system’s performance towards achieving a substantial qubit count and interaction fidelity, thus maintaining its competitive edge in the quantum computing landscape. The establishment of standardized, rack-based setups signifies a pivotal shift in the endeavor to make quantum computational systems a mainstream tool for computational problem-solving.