Today, the first Quantum Computing Cloud Service is launched in Japan
As a step toward building a quantum computing platform using quantum computers, the Japan Joint Research Group on Quantum Computing has prepared the first domestic quantum computer based on the superconducting method. on March 27, a cloud service using this machine was launched and is available for external use via the Internet. At present, users will go through the procedure of using it through a cooperative agreement with RIKEN.
The joint team is composed of Yasunobu Nakamura (Director, RIKEN Quantum Computer Research Center); Katsuya Kikuchi (Research Group Leader, AIST 3D Integrated Systems Group); Hirotaka Terai (Director, NICT Superconducting ICT Laboratory); Katsuhiro Kitagawa, (Director, Osaka University Quantum Information and Quantum Life Research Center and Professor, Graduate School of Engineering Science); Keisuke Fujii (Deputy Director, RIKEN Basic Engineering Professor, Graduate School of Engineering Science, RIKEN); and Shintaro Sato (Director, Quantum Science Laboratory, Fujitsu Limited), consisting of Professor Katsuhiro Kitagawa (Professor, Graduate School of Engineering Science), Professor Keisuke Fujii (Professor, Graduate School of Engineering Science, RIKEN), Dr. Shintaro Sato (Director, Quantum Science Research Institute, Fujitsu Limited), and Hiroki Tokunaga D. (Researcher, Computer and Data Science Laboratory, Nippon Telegraph and Telephone Corporation) have been working to develop a quantum computer on March 27, 2023. The quantum computer currently scales to 64 quantum bits, and future research and development will continue to achieve milestones such as 100 quantum bits and 1,000 quantum bits.
The first domestic superconducting quantum computer in Japan has two features: "two-dimensional integrated circuit" and "vertical wiring package".
In the "two-dimensional integrated circuit," four quantum bits arranged in a square are connected by "quantum bit-to-bit coupling" that connects adjacent quantum bits. "Multiple readout filter circuits", etc. By arranging these basic units of four quantum bits in two dimensions, a quantum bit integrated circuit can be made. This 64-qubit integrated circuit consists of 16 functional units on a 2 cm2 silicon chip.
(Left) A 64-quantum-bit 2D integrated circuit chip. A design of 16 basic cells consisting of 4 quantum bits is arranged. (Upper right) Schematic of a basic cell composed of four quantum bits. The quantum bits are arranged in the four corners of the square, and the readout circuit is placed in the center. (Bottom right) Electron micrograph of the Josephson junction that makes up the quantum bits. Source: RIKEN
The "two-dimensional integrated circuit" is also highly scalable. The number of integrated quantum bits can be increased by periodically arranging a basic cell of four quantum bits on a plane. 64 quantum bits are arranged in a 4x4 array to create a future projection of 1024 quantum bits. Source: RIKEN
When the wiring to control and read out individual quantum bits is in the same plane as the quantum bits, the length of the edge leading the wiring out to the outside is not long enough for the number of quantum bits arranged in the chip. For efficient wiring, a "vertical wiring package" connects the wiring to the quantum bits arranged in a two-dimensional plane perpendicular to the chip. In addition, they are developing a wiring package that connects the wiring to a quantum bit integrated circuit chip in one pass.
(Left) A conceptual drawing of a vertical wiring package. The control/readout lines of the quantum bits are connected to the chip vertically through signal contact probes. Microwave signals are transmitted and received through this wiring. (Right) Wiring package with a quantum bit integrated circuit chip. Source: RIKEN
Superconducting quantum computers use voltage pulses oscillating at microwave frequencies from 8G to 9GHz as signals to control quantum bits, but different quantum bits require different frequencies of microwaves. For this reason, a control device capable of generating high-precision, phase-stable microwave pulses and software for controlling quantum bits using this device were developed and applied to the first Japanese domestic superconducting quantum computer.
Quantum bit controller. Source: RIKEN
The Quantum Computing Cloud Service is made possible through a collaboration between research institutions (including universities) and companies in Japan. This service is not only expected to lead to the development of human resources for domestic quantum information research in Japan at the research and development stage, but also to promote the development of domestic industries in the information technology-based field.
The "Quantum Computing Cloud Service" will be launched on March 27, 2023, enabling the use of the first domestic superconducting quantum computer anytime and anywhere. Any researcher/engineer can apply for non-commercial use to promote/develop R&D such as quantum computing. However, procedures for use will currently be developed through a joint research contract with RIKEN. By connecting to a cloud server external to RIKEN, users can send jobs to the superconducting quantum computer and receive calculation results.
Conceptual diagram of user access to quantum computing cloud services. Source: RIKEN
The joint research team is working on further system development, such as increasing the wiring density in the dilution cooler to enable quantum computing operations with more quantum bits. In addition, while providing the first Japanese-made superconducting quantum computer as a testbed for the NISQ (Noisy Intermediate-Scale Quantum: Noisy Intermediate-Scale Quantum Device) application platform, the current 64 quantum bits will be further increased according to user needs, and the company plans to conduct the necessary research and development to increase the complexity.
Reference link:
https://www.riken.jp/pr/news/2023/20230324_1/index.html
