R&D Themes

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Quantum Computing System

Hitachi, Ltd.（＃1～3）is engaged in the research and development of a quantum computing system consisting of the development of a 2D qubit array and the circuitry to control it. It includes the quantum physical design and the logical design to operate it, and the whole system works together as a computer.

Principal Investigators(PIs)：Hitachi　Hiroyuki Mizuno

▼ R&D Challenges

#1. 2D qubit array

#2．High-precision qubit control and high-sensitive qubit readout circuit

#3．System architecture

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Multi-chip Cryogenic Packaging System

Kobe University（＃4、5）is promoting research on multi-chip cryogenic packaging systems that integrate components, including semiconductor chips, in the required environment. This includes signaling technology and simulation technology including heat. In addition, the high-precision qubit control and high-sensitivity qubit readout circuits in this research uses digital correction techniques that take advantage of various data obtained from a large number of qubits. Since reproducibility of qubit operation is key to this, we will also monitor the environment (voltage, temperature, etc.) inside the dilution refrigerator, which affects reproducibility. Kobe University’s research will be used as Hitachi’s quantum computing system, and environmental data will be fed back to the qubit control.

Principal Investigators(PIs)：Kobe University　Makoto Nagata

▼ R&D Challenges

#4. Multi-chip cryogenic packagiing

#5．Environmental monitoring

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Hot Silicon Qubits

Kodera’s team at Institute of SCIENCE TOKYO（＃6）is working to make silicon qubits operate at as high a temperature as possible based on theoretical quantum physics research on silicon qubits. In principle, the operating temperature of silicon qubits can be higher than that of superconducting quantum computers, which means that the cooling capacity of refrigerators can be significantly increased, which is one of the keys to overcoming thermal problems in implementation.（＃6）

Principal Investigators(PIs)：Institute of SCIENCE TOKYO Tetsuo Kodera

▼ R&D Challenges

#6. High temperature operation of silicon qubits

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Quantum Computing in Small Qubit Systems

Yoneda’s team at Institute of SCIENCE TOKYO（＃7）and Nakajima’s team at RIKEN (#8) will fabricate a basic “small-scale experimental circuit” that constitutes a qubit array chip, which is the R&D theme of Hitachi, Ltd. This will allow us to evaluate the performance of the qubit, identify issues that arise when scaling it up, and optimize the qubit array structure.