FEBQI

Building S51

2-1 Hirosawa, Wako

Saitama 351-0198, Japan

rikenEonHe@gmail.com

We are the Floating-Electron-Based Quantum Information (FEBQI) research team at RIKEN.

Our research focuses on electrons floating above liquid helium and solid neon as platforms for quantum information processing. These electrons exist in a pristine, defect-free environment, enabling long coherence times ideal for quantum computing.

Research Highlights

Electrons on liquid helium — Scalable electron spin qubits exploiting the clean electron-on-helium system
Electrons on solid neon — Long coherence times for both charge and spin states, targeting quantum memory
Cryogenic electronics — Development of cryogenic microwave sources for scaling up qubit numbers

Openings

We are recruiting postdocs and interns (3+ months). Please contact Erika Kawakami for details.

news

Oct 31, 2024	Our plasmon paper is now on arXiv! New results on collective excitations (plasmon modes) of electrons floating on liquid helium.
Aug 31, 2024	We are recruiting postdocs and interns (3+ months). Contact erika.kawakami@riken.jp for details.
Mar 31, 2024	New cryogenic microwave source developed using a tunnel diode oscillator — achieving superior amplitude stability compared to commercial sources.

latest posts

Apr 22, 2026
Mar 25, 2026	Hochan Chung receives Best Bachelor's Thesis Award
Mar 10, 2026	Birthdays

selected publications

arXiv

Strong Coupling Between RF Photons and Plasmons of Electrons on Liquid Helium

Asher Jennings^* , Ivan Grytsenko , Thomas Giovansili , Itay Josef Barabash , Oleksiy Rybalko , Yiran Tian , Jun Wang , Hiroki Ikegami , and Erika Kawakami^*

arXiv:2601.22552 (2026).

arXiv Bib

@article{jennings2025plasmon,
  title = {Strong Coupling Between RF Photons and Plasmons of Electrons on Liquid Helium},
  author = {Jennings, Asher and Grytsenko, Ivan and Giovansili, Thomas and Barabash, Itay Josef and Rybalko, Oleksiy and Tian, Yiran and Wang, Jun and Ikegami, Hiroki and Kawakami, Erika},
  journal = {arXiv},
  year = {2026},
}

PRA

Nb-Ti-N nanowire resonators and prospects for spin-photon coupling with electrons on solid neon

Yiran Tian , Ivan Grytsenko , Asher Jennings , Jun Wang , Hiroki Ikegami , Xianjing Zhou , Shuhei Tamate , Hirotaka Terai , Hiroki Kutsuma , Dafei Jin , Monica Benito , and Erika Kawakami^*

Phys. Rev. Applied 25, 024011 (2026).

DOI arXiv Bib Journal Overleaf

@article{tian2025neon,
  title = {Nb-Ti-N nanowire resonators and prospects for spin-photon coupling with electrons on solid neon},
  author = {Tian, Yiran and Grytsenko, Ivan and Jennings, Asher and Wang, Jun and Ikegami, Hiroki and Zhou, Xianjing and Tamate, Shuhei and Terai, Hirotaka and Kutsuma, Hiroki and Jin, Dafei and Benito, Monica and Kawakami, Erika},
  journal = {Phys. Rev. Applied},
  volume = {25},
  pages = {024011},
  year = {2026},
  doi = {10.1103/jq9v-n4rn},
  overleaf = {https://www.overleaf.com/read/vhqcrdqczzjc#4a4b63},
  index = {2024 neon SC nanowire},
}

PRL

Probing the Quantum Capacitance of Rydberg Transitions of Surface Electrons on Liquid Helium via Microwave Frequency Modulation

Asher Jennings^* , Ivan Grytsenko , Yiran Tian , Oleksiy Rybalko , Jun Wang , Itay Josef Barabash , and Erika Kawakami^*

Phys. Rev. Lett. 135, 087001 (2025).

DOI arXiv Bib Journal Overleaf

@article{jennings2025rydberg,
  title = {Probing the Quantum Capacitance of Rydberg Transitions of Surface Electrons on Liquid Helium via Microwave Frequency Modulation},
  author = {Jennings, Asher and Grytsenko, Ivan and Tian, Yiran and Rybalko, Oleksiy and Wang, Jun and Barabash, Itay Josef and Kawakami, Erika},
  journal = {Phys. Rev. Lett.},
  volume = {135},
  pages = {087001},
  year = {2025},
  doi = {10.1103/5y8p-qhb4},
  overleaf = {https://www.overleaf.com/read/wnybdtvxsxyk#ca9ad5},
  index = {2024 Rydberg FM},
}

APL

Quantum computing using floating electrons on cryogenic substrates: Potential And Challenges

Asher Jennings^* , Xianjing Zhou , Ivan Grytsenko , and Erika Kawakami^*

Appl. Phys. Lett. 124, 120501 (2024).

DOI arXiv Bib Journal Overleaf

@article{jennings2024perspectives,
  title = {Quantum computing using floating electrons on cryogenic substrates: Potential And Challenges},
  author = {Jennings, Asher and Zhou, Xianjing and Grytsenko, Ivan and Kawakami, Erika},
  lab_members = {Zhou},
  journal = {Appl. Phys. Lett.},
  volume = {124},
  pages = {120501},
  year = {2024},
  doi = {10.1063/5.0179700},
  overleaf = {https://www.overleaf.com/read/knxxdvsvhvyt#29ec0d},
  index = {2024 APL Perspectives},
}

PRA

Blueprint for quantum computing using electrons on helium

Erika Kawakami^* , Jiabao Chen , Monica Benito , and Denis Konstantinov

Phys. Rev. Applied 20, 054022 (2023).

DOI arXiv Bib Journal Overleaf

@article{kawakami2023blueprint,
  title = {Blueprint for quantum computing using electrons on helium},
  author = {Kawakami, Erika and Chen, Jiabao and Benito, Monica and Konstantinov, Denis},
  journal = {Phys. Rev. Applied},
  volume = {20},
  pages = {054022},
  year = {2023},
  doi = {10.1103/PhysRevApplied.20.054022},
  overleaf = {https://www.overleaf.com/read/gbxxyfjxmrgq#de6658},
  index = {2023 PRApplied Blueprint},
}