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.

Coupling of Tin-vacancy qubits with large-scale diamond photonic circuits on diamond-on-insulator (DOI) substrate platform

Coupling diamond defect spin qubits with nanophotonic circuits/structures is critical for efficient qubit readout, remote entanglement, and large-scale diamond-based quantum computer, network system implementation. However, fabricating such nanophotonic cavities accurately in diamond and coupling the color center emitters spatially and spectrally with such cavities are highly challenging. Therefore, a large-scale fabrication and high-yield emitter-cavity coupling process has to be developed to realize a scalable, on-chip quantum system, where thousands of qubits can be interconnected and entangled efficiently for useful quantum computing.

Tin-vacancy (SnV) centers in diamond are particularly promising for large-scale integration of quantum systems because of their charge noise insensitivity due to inversion symmetry, narrow-linewidth and larger ZPL emission (DW factor ~ 0.57), good compatibility of coupling with nanophotonic structures, long spin coherence times at temperatures above 1 K, etc. Hence, developing an integration process for a large-scale, SnV center-coupled, photonic circuit will be a critical step toward the realization of a useful quantum computer and network.

Project goal/tasks:

• Deterministic implantation of tin vacancies in DOI substrates with effective markers
• Fabricate photonic circuits on tin-implanted DOI substrates using an alignment marker for efficient spatial and spectral coupling of tin-vacancy qubits.
• Identifying issues in marker designs, and fabrication process steps. Then, carefully adjust the design, and process steps in the next iteration.
• Devise optimal design methodologies and process steps for large-scale, qubit-coupled photonic circuits in DOI substrate.

References:

[1]. Alison E. Rugar, and et al., Quantum Photonic Interface for Tin-Vacancy Centers in Diamond, Physical Review X, 11, 031021 (2021)

[2]. Maximilian Ruf, and et al., Quantum networks based on color centers in diamond, Journal of Applied Physics 130, 070901 (2021)

[3]. Noel H. Wan*, Tsung-Ju Lu and et al., Large-scale integration of artificial atoms in hybrid photonic circuits, Nature 583, 226–23 (2020).

[4]. 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>