The Kavli IPMU CMB Group is pursuing the research on the physics of the early universe using the measurement of the cosmic microwave background (CMB) polarization. The theory of cosmic inflation can be tested by the measurement of CMB polarization pattern called, B-mode, experimentally.



LiteBIRD is the JAXA/ISAS second strategic large-class satellite mission. It is the first space mission dedicated to CMB polarization measurements from L2. The Kavli IPMU is responsible for delivering the polarization modulator unit for low-frequency telescope and the data center.

POLARBEAR, POLARBEAR2(PB2)/Simons Array is the ground-based telescopes located in the Atacama Desert, Chile. POLARBEAR has finished observing and the analysis is in progress. POLARBEAR2/Simons Array has deployed and started the observation in 2021.

The next generation ground-based telescope, Simons Observatory (SO), is being built in the Atacama Desert, Chile. The Kavli IPMU has been actively participating to build the Small Aperture Telescope (SAT) of SO.

Future Missions

We actively participate in concept studies for future missions, including ground-baed experiments such as CMB-S4, other space-mission concepts such as PICO, next generation balloon-borne missions, and more.

New Technologies

Millimeter optical components and characterizations

We develop novel technologies related to millimeter and THz optical components and their characterizations, including broadband anti-reflection coating, wave plates, absorbers, filters, and heaters.


Moving parts at cryogenic temperatures are of unique importance in experimental physics. We develop mechanisms that operate at cryogenic temperatures, including superconductive magnetic bearing and low-heat dissipation devices at LN2 and LHe temperature ranges. In particular, we aim to develop space-qualified components.

Cryogenic detector characterization

We study detector performance, e.g. transition edge sensor bolometer, cooled down to sub-Kelvin, and connect it to implications to cosmology via observations of CMB polarization.

Algorithm development

We develop new algorithm for instrument design, simulation method, and data analysis software. For example, studies of systematic effects and calibration with a focus on the bridge to instrumentation and cosmology. New algorithm development can be also expanded to other cosmological deliverables, e.g. delensing, non-Gaussianity.



  • Nobuhiko Katayama, Prof.

  • Tomotake Matsumura, Associate Prof.


  • Eiichiro Komatsu, Director of the Department of Physical Cosmology at MPA

Scientific Associates

  • Masashi Hazumi, Prof. at KEK


  • Yuki Sakurai, Dr.

  • Tommaso Ghigna, Dr.

  • Shunsuke Adachi, Dr.

  • Takashi Hasebe, Dr.

Students including via collaborations

  • Kunimoto Komatsu (Ishino Lab. at Okayama U.)

  • Shinya Sugiyama (Tashiro Lab. at Saitama U.)

  • Susanna Azzoni (U. Oxford/Kavli IPMU)

  • Ryota Takaku (Yamasaki lab at U. Tokyo)

  • Yurika Hoshino (Tashiro Lab. at Saitama U.)

Affiliated members

  • Akito Kusaka, Associate Prof. at Dept. of Physics, U. Tokyo

  • Chinone, Yuji, Assistant Prof. at Dept. of Physics, U. Tokyo

  • Samantha Stever, Assistant Prof. at Okayama U.

Past members

  • Frederick Takayuki Matsuda (ISAS/JAXA), -JFY2020

  • Satoru Takakura (NIES), -JFY2020

  • William Coulton (CCA Flatiron), -JFY2020

  • Daisuke Kaneko (KEK), -JFY2020

  • Hiroaki Imada (NAOJ), -JFY2020

  • Hajime Sugai (JWA), -JFY2019

  • Samantha Stever (Okayama U.), , -JFY2019

  • ...


Kavli Institute for the Physics and Mathematics of the Universe

The University of Tokyo

5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8583, Japan

Kavli IPMU website: access


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