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



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

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

The next generation ground-based telescope, Simons Observatory (SO), is currently being built in the Atacama Desert, Chile. Kavli IPMU has been actively participating in building 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 we work on the characterization, 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 temperatures. In particular, we aim at developing space-qualified components.

Cryogenic detector characterization

We study the performance of low-noise superconductive detectors, e.g. transition edge sensor bolometers, cooled down to sub-Kelvin. A big research topic at the moment is to develop more realistic response models to propagate non-ideal behaviors to the impact on cosmological data.

Linking Theory and Observation

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 between instrumentation and cosmology. New algorithm development can be also expanded to other cosmological deliverables, e.g. delensing, non-Gaussianity.

(BICEP/Keck Array Collaborations 2018)

Data Analysis

We analyze CMB data taken by ongoing CMB experiments and provide new implications for cosmology. For example, our studies include measurement of gravitational lensing of CMB to probe neutrino mass, dark matter, dark energy, and B-mode delensing analysis to explore inflationary gravitational waves.

Synergy between CMB and other cosmological probes

We explore synergy between CMB observations and other cosmological probes such as galaxy surveys and gravitational-wave interferometers. We also work on theoretical prediction of cosmological observables which is necessary for the interpretation of observed data.


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


If you have any questions or are interested in working with us, please contact us here.