A Polarization Modulator Unit for the Mid- and High-Frequency Telescopes
  of the LiteBIRD mission
  The LiteBIRD mission is a JAXA strategic L-class mission for all sky CMB
surveys which will be launched in the 2020s. The main target of the mission is
the detection of primordial gravitational waves with a sensitivity ofthe
tensor-to-scalar ratio {\delta}r <0.001. The polarization modulator unit (PMU)
represents a critical and powerful component to suppress 1/f noise contribution
and mitigate systematic uncertainties induced by detector gain drift, both for
the high-frequency telescope (HFT) and for the mid-frequency telescope (MFT).
Each PMUs based on a continuously-rotating transmissive half-wave plate (HWP)
held by a superconducting magnetic bearing in a 5K environment. In this
proceeding we will present the design and expected performance of the LiteBIRD
PMUs and testing performed on every PMU subsystem with a room-temperature
rotating disk used as a stand-in for the cryogenic HWP rotor.
