Welcome to the Quantum Integration Technology (QIT) group led by Ryoichi Ishihara


The research group Quantum Integration Technology (QIT) performs research on scalable and manufacturable integration technology of quantum and electronic devices for future quantum computer and network. QIT also performs research on flexible thin-film transistors and sensors using printing of silicon for bio-compatible wearable and implantable electronic systems.

3D integration for quantum computers/sensors

We focus on the integration techniques for the control and sensing components of diamond vacancy centers for scalable quantum computing and sensing applications. Our work involves the fields of new materials, scalable fabrication of electronic and photonic devices, and 3D integration technology with the ultimate goal to integrate a large quantum system on chip.

Printed Silicon Electronics

Printed flexible electronics has attracted a lot of attention for the low-cost fabrication of novel electronic products like flexible displays, RF-ID tag and sensors. However due to the low performance and inferior reliability of the semiconductor material, printed electronics has not been introduced in the market. The goal of this research is to print high-speed and low-power Si electronics directly on a flexible and stretchable substrate, such as PET and paper. Liquid-Si is the promising candidate as ink for the solution process of silicon devices for applications of low-cost, large-area and biodegradable electronics.

If you are interested in our research, please contact Ryoichi Ishihara.

Overview of Research Topics

3D Integration and wafer-scale diamond process

Developing scalable fabrication and on-chip integration processes for diamond-based quantum technologies. The research encompasses incorporation of photonic and electronic circuits with spins in diamond and integration of diamond color centers for realizing a scalable, compact and fast quantum computer.

On-chip quantum sensing

This project focuses on the CMOS integration of Nitrogen-Vacancy (NV) centers in diamond, into an on-chip platform. The goal is to create a compact, high sensitivity quantum sensor, utilizing ODMR measurement techniques, for the purpose of magnetic field sensing for bio-imaging applications, at room temperature. By integrating a single photon detector (SPAD), we will be able to perform even more accurate measurements, further increasing the platform’s detection efficiency and sensitivity.

Direct bonding of diamond on insulator

This research aims to successfully bond a (100)-oriented diamond substrate directly to the silicon wafer which will be the basis for generating colour centers in diamond for future quantum technologies. Several process parameters will be systematically investigated on a successful direct bonding such as chemical treatment time, deposition techniques, and after-annealing cooling period. Also, parameters such as flatness and roughness are also being investigated.

Magnetic field tuning

Color centers in diamond, used as qubits in a quantum computer or network have driving and emission characteristics that are heavily affected by the presence of external magnetic fields. Magnetic field tuning can enable higher entanglement rates and driving/emission multiplexing. Tuning with conventional metal coils, however, increasing power dissipation, which is limited by the cryostation cooling power. Superconducting materials are therefore pursued for an ultra-low power operation

Photonic circuit

Utilizing color vacancy center for quantum computers requires optical excitation and readout. The group is currently designing and fabricating photonic integrated circuits in the visible wavelength region to control the vacancy center. This includes optical waveguide, optical switch and variable optical attenuator (VOA). We are now using MEMS technology to achieve a fast, low-loss optical switch with high extinction ratio for cryogenic environments.


Printed Silicon Electronics
3D Integration
Diamond on Chip
Diamond Bonding
MFG Simulation
Photonic Circuit
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