P.A.R. Ade, Y. Akiba, A.E. Anthony, K. Arnold, M. Atlas, D. Barron, D. Boettger, J. Borrill, S. Chapman, Y. Chinone, M. Dobbs, T. Elleflot, J. Errard, G. Fabbian, C. Feng, D. Flanigan, A. Gilbert, W. Grainger, N.W. Halverson, M. Hasegawa, K. Hattori, M. Hazumi, W.L. Holzapfel, Y. Hori, J. Howard, P. Hyland, Y. Inoue, G.C. Jaehnig, A.H. Jaffe, B. Keating, Z. Kermish, R. Keskitalo, T. Kisner, M. LeJeune, A.T. Lee, E.M. Leitch, E. Linder, M. Lungu, F. Matsuda, T. Matsumura, X. Meng, N.J. Miller, H. Morii, S. Moyerman, M.J. Myers, M.J. Myers, M. Navaroli, H. Nishino, A. Orlando, H. Paar, J. Peloton, D. Poletti, E. Quealy, G. Rebeiz, C.L. Reichardt, P.L. Richards, C. Ross, I. Schanning, D.E. Schenck, B.D. Sherwin, A. Shimizu, C. Shimmin, M. Shimon, P. Siritanasak, G. Smecher, H. Spieler, N. Stebor, B. Steinbach, R. Stompor, A. Suzuki, S.Takakura, T. Tomaru, B. Wilson, A. Yadav, O. Zahn
Polarbear is a ground-based experiment located in the Atacama desert of northern Chile. The experiment is designed to measure the Cosmic Microwave Background B-mode polarization at several arcminute resolution. The CMB B-mode polarization on degree angular scales is a unique signature of primordial gravitational waves from cosmic in ation and B-mode signal on sub-degree scales is induced by the gravitational lensing from large-scale structure. Science observations began in early 2012 with an array of 1,274 polarization sensitive antenna-couple Transition Edge Sensor (TES) bolometers at 150 GHz. We published the first CMB-only measurement of the B-mode polarization on sub-degree scales induced by gravitational lensing in December 2013 followed by the first measurement of the B-mode power spectrum on those scales in March 2014. In this proceedings, we review the physics of CMB B-modes and then describe the Polarbear experiment, observations, and recent results.