A Microwave-Based QCCD Trapped-Ion Quantum Computer with Scalable Control System
Takefumi Miyoshi, Keisuke Koike, Shinichi Morisaka, T. Sumida, Makoto Negoro, Atsushi Noguchi, Ryutaro Ohira · 2024
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.