Ryoichi Ishihara

Associate Professor, Group leader

Qutech, Dep. Quantum and Computer Engineering, Faculty of Electrical Engineering, Mathematics and Computer Science, Delft University of Technology

Ishihara-lab focuses on the integration technologies for unconventional electronic systems; quantum computers, quantum sensors, neuromorphic computers, and biodegradable sensors. Our work involves new materials, scalable fabrication of electronic and photonic devices, and 3D heterogeneous integration, aiming to realize unconventional electronic systems.

Fabrication and testing of superconducting magnetic field generator for local tuning of spin qubits in diamond

Diamond color centers present promising prospects for creating an effective solid-state interface between spin and photon. This interface is key for developing a scalable and modular quantum computer using the spins of these color centers. To define qubits, a strong magnetic field is necessary to separate the spin states of the color centers. Besides this strong, overarching magnetic field (about 1 Tesla), introducing a smaller, adjustable magnetic field (in the millitesla range) near each color center is beneficial. This smaller field helps offset external field irregularities and enables the distinct tuning of qubit operation frequencies. Achieving local adjustments in the magnetic field strength could be done by running direct currents through tiny coils situated near the relevant color centers. Considering these systems operate at cryogenic temperatures where cooling capacity is limited, superconducting coils are preferred over traditional metal coils for this local tuning. In this project, we fabricate and test superconducting magnetic field generator for local tuning of spin qubits in diamond

Project goal/tasks:

• To deposit and fabricate NbTiN superconducting coils on a diamond substrate
• Electrical characterization of the fabricated NbTiN coils at cryogenic temperatures.
• Fabricate and couple SC coils with implanted color centers in diamond and investigate local tuning.

References:

[1]. Ishihara, R. et al. 3D Integration Technology for Quantum Computer based on Diamond Spin Qubits. 2021 Ieee Int Electron Devices Meet Iedm 00, 14.5.1-14.5.4 (2021).

Interested? Please contact Ryoichi Ishihara r.ishihara@tudelft.nl or Salahuddin Nur <S.Nur@tudelft.nl>