This paper proposes a control system capable of supporting various qubit platforms by combining control units with different specifications with a lightweight and common interface. To realize quantum computers, several qubit platforms, such as superconducting qubits, neutral atoms, ion traps, and semi-conductor quantum dots, are being researched. Each platform requires different microwave frequencies, channel numbers, intensities, and time scales for control. However, building individual control systems for each platform is not practical from a development cost perspective. Therefore, the standardization of control systems is desired. In practice, common languages and libraries for pulse control software are being developed as both commercial products and open-source projects. However, no widely adopted standardization methods currently exist for the control layer of electrical signals responsible for qubit manipulation. This paper first organizes the challenges in standardizing the control layer of electrical signals. It then proposes an architecture to address these challenges, featuring Ethernet-based unit inter-connections, a synchronization system based on time and pulses, and a lightweight and flexible waveform generation method. The proposed approach allows for practical cost adaptation to various types of qubits by connecting electronic circuits with specifications required for the target qubit platform.
This paper proposes a control system capable of supporting various qubit platforms by combining control units with different specifications with a lightweight and common interface. To realize quantum computers, several qubit platforms, such as superconducting qubits, neutral atoms, ion traps, and semi-conductor quantum dots, are being researched. Each platform requires different microwave frequencies, channel numbers, intensities, and time scales for control. However, building individual control systems for each platform is not practical from a development cost perspective. Therefore, the standardization of control systems is desired. In practice, common languages and libraries for pulse control software are being developed as both commercial products and open-source projects. However, no widely adopted standardization methods currently exist for the control layer of electrical signals responsible for qubit manipulation. This paper first organizes the challenges in standardizing the control layer of electrical signals. It then proposes an architecture to address these challenges, featuring Ethernet-based unit inter-connections, a synchronization system based on time and pulses, and a lightweight and flexible waveform generation method. The proposed approach allows for practical cost adaptation to various types of qubits by connecting electronic circuits with specifications required for the target qubit platform.
Quantum computing requires scalable control hard-ware capable of generating precise signals and synchronizing operations across large numbers of qubits. However, existing control systems are typically optimized for specific qubit modalities, leading to limited interoperability, high development cost, and poor scalability as device architectures evolve. To address this challenge, a heterogeneous and modular control architecture supporting multiple qubit platforms was previously proposed.This paper evaluates FPGA resource requirements and implementation characteristics of the architecture across four controller variants targeting high-frequency microwave, mid-frequency RF, low-frequency DAC, and digital GPIO applications. The results show that core architectural components—including networking, synchronization, and waveform generation—maintain nearly constant hardware usage across platforms, while resource scaling primarily depends on data throughput requirements rather than architectural complexity.Moreover, the architecture is demonstrated on both high-end FPGAs with high-bandwidth memory and cost-efficient embedded devices, confirming portability and deployment flexibility. These findings validate the feasibility of a unified control framework suitable for heterogeneous quantum systems and large-scale control networks.
Quantum circuits utilizing real time feedback techniques (such as active reset and mid-circuit measurement) are a powerful tool for NISQ-era quantum computing. Such techniques are crucial for implementing error correction protocols, and can reduce the resource requirements of certain quantum algorithms. Realizing these capabilities requires flexible, low-latency classical control. We have developed a custom FPGA-based processor architecture for QubiC, an open source platform for superconducting qubit control. Our architecture is distributed in nature, and consists of a bank of lightweight cores, each configured to control a small (1-3) number of signal generator channels. Each core is capable of executing parameterized control and readout pulses, as well as performing arbitrary control flow based on mid-circuit measurement results. We have also developed a modular compiler stack and domain-specific intermediate representation for programming the processor. Our representation allows users to specify circuits using both gate and pulse-level abstractions, and includes high-level control flow constructs (e.g. if-else blocks and loops). The compiler stack is designed to integrate with quantum software tools and programming languages, such as TrueQ, pyGSTi, and OpenQASM3. In this work, we will detail the design of both the processor and compiler stack, and demonstrate its capabilities with a quantum state teleportation experiment using transmon qubits at the LBNL Advanced Quantum Testbed.
Quantum computing has made significant strides, with hardware platforms now advanced enough to tackle the challenges of scaling up to larger and more robust systems. Central to this progression is the interface between quantum processors, comprising isolated qubits, and the classical systems required for their control and readout. As these systems transition from few-qubit devices to fault-tolerant architectures, the complexity of this quantum-classical interaction poses significant engineering challenges. Field-Programmable Gate Arrays (FPGAs) have emerged as an adaptable and efficient solution, offering realtime control, low-latency operations, and seamless integration. This review delves into current FPGA-based platforms, including commercial systems, as well as open-source solutions developed by academic research groups. The architecture, features, and contributions of these platforms to addressing scalability and integration issues are thoroughly examined. Additionally, the review highlights innovations in cryogeniccompatible controllers and explores the potential of Cryo-FPGAs to reduce noise and improve fidelity in quantum systems. By providing a comprehensive analysis of current technologies and identifying opportunities for advancement, this review offers valuable insights for researchers and engineers working to develop scalable quantum computing solutions.
This paper proposes a scalable control device architecture for trapped-ion quantum computers based on microwave quantum control. While microwave control of trapped-ion qubits offers high gate fidelity, it requires high-precision and scalable microwave control devices. In the control devices for microwavebased trapped-ion quantum computers, three types of signals need to be managed: (1) wideband microwaves with low phase noise for quantum gate operations, (2) numerous signals with sub-microsecond voltage changes to implement the quantum charge-coupled device (QCCD) architecture, and (3) triggers to synchronize measurement instruments. The proposed architecture combines heterogeneous control devices tailored to these three types of signals to achieve the required precision and scalability at a practical cost. The system features a shared sequencer that can manage all units uniformly, ensuring scalability and reducing development costs. To correctly execute the control sequences, it is necessary to align the operating timing of each unit. In the proposed system, each unit maintains a common time and independently issues events by referring to this time. High-precision time synchronization protocols based on IEEE1588 can be used for time synchronization. In addition to that, multiple control devices can be expanded by combining fine-grained synchronization mechanisms using time synchronization and shared reference signals. This paper details the specifications required for trappedion quantum computers using microwaves and proposes an architecture that meets these specifications.
Researchers manipulate and measure quantum processing units via the classical electronics control system. We developed an open-source FPGA-based quantum bit control system called QubiC for superconducting qubits. After years of qubit calibration and testing experience on QubiC 1.0, we recognized the need for mid-circuit measurement and feed-forward capabilities to implement advanced quantum algorithms, and upgraded the system to QubiC 2.0 on an AMD ZCU216 RFSoC evaluation board with all these enriched features. The system uses portable FPGA gateware with a simplified processor to handle commands on-the-fly. For design simplicity and straightforward scaling, we adopted a multi-core distributed architecture, assigning one processor core per qubit. The pulses combine the unique pulse envelope and carrier information specified in a command. Each pulse envelope is pre-stored in the FPGA's block RAMs, ensuring speed and reusability throughout the quantum circuit, while pulse parameters including amplitude, phase, and frequency can be updated from pulse to pulse. The software stack is developed in Python, running on both the FPGA's ARM core and a host computer via XML-RPC. Quantum circuits can be described in a high-level language supporting both pulse-level and native-gate-level programming with high-level control flow constructs, and are compiled into binary commands loaded into the FPGA. With QubiC 2.0, we achieved multi-FPGA synchronization and low-latency data communication, and demonstrated feed-forward experiments on conditional circuits. The system also serves as a platform for artificial intelligence and machine learning driven quantum control, such as FPGA-based real-time quantum state discrimination. The enhanced QubiC system provides researchers with powerful tools to explore and implement advanced quantum algorithms and applications.
Quantum circuits utilizing real time feedback techniques (such as active reset and mid-circuit measurement) are a powerful tool for NISQ-era quantum computing. Such techniques are crucial for implementing error correction protocols, and can reduce the resource requirements of certain quantum algorithms. Realizing these capabilities requires flexible, low-latency classical control. We present the development of an open-source FPGA (field-programmable gate array) based processor for pulse-level qubit control. Our processor is designed primarily as an upgrade to QubiC, an open source qubit control platform, but can also be adapted to other systems. The processor is distributed in nature, with one core per arbitrary waveform generator (AWG); simplifying the design and allowing for straightforward scaling. Each processor core implements an instruction set consisting of timed pulse commands as well as simple arithmetic and branching instructions. Our design also includes interfaces for synchronizing the different cores and requesting/receiving (optionally processed) measurement results. Together, these features will allow a user to program arbitrary control flow within a quantum circuit based on previous measurement results. In this poster, we detail our design along with the expected resource utilization on the Xilinx Virtex 7 FPGA, and present pulse-level simulations of our system in the context of a simple feedback experiment.