RESEARCH

Superfluid ³He is the established spin-triplet p-wave fermionic condensate. It is drawing a renewed interest recently, since theorists pointed out it is a time-reversal invariant topological superfluid. I have been studying the surface bound states of superfluid ³He B-phase, which are the Majorana fermions formed due to the bulk-edge correspondence. On a wall of weak disorder, Majorana cone was detected by the transverse acoustic wave impedance measurement. On a wall of higher disorder, I revealed a peculiar behavior of the surface density of states which reflects an anomalous scattering property of Majorana fermions.

Majorana fermions in zero magnetic field without interaction have been studied by the transverse acoustic impedance. We will extend this measurement in magnetic field at higher pressures in order to examine their topological stabilities and the mass acquisition process.

EDUCATION

1991

Bachelor of Science, Kyoto University

2000

Ph.D. (Physics), Kyoto University

PROFESSIONAL EXPERIENCE

1998-2000

Research fellow, Northwestern University

2000-2007

Research associate, Graduate School of Science, Tokyo Institute of Technology

2007-Present

Assistant Professor, Department of Physics, Tokyo Institute of Technology

HONORS AND AWARDS

2007

Young Scientist Award of Physical Society of Japan

2013

A research encouragement award for young researchers of Tokyo Tech. department of science, 2012

2013

18th Outstanding Paper Award of the Physical Society of Japan

SELECTION OF PUBLICATIONS

"Crystallization of ⁴He in Aerogel via Mass Flow from Surrounding Solid ⁴He"
H. Matsuda, A. Ochi, R. Isozaki, S. Minami, R. Nomura, J. Pollanen, W. P. Halperin, and Y. Okuda
Physical Review B 94, 024509-1-7 (Jul. 2016)
DOI: 10.1103/PhysRevB.94.024509

"Control of the wetting properties of ⁴He crystals in superfluid"
T. Takahashi, H. Minezaki, A. Suzuki, K. Obara, K. Itaka, R. Nomura, and Y. Okuda
Physical Review E 93, 052806-1-6 (May. 2016)
DOI: 10.1103/PhysRevE.93.052806

"Equilibrium Shape of ⁴He Crystal under Zero Gravity below 200 mK"
T. Takahashi, H. Ohuchi, R. Nomura, and Y. Okuda
Science Advances 1, e1500825-1-5 (Oct. 2015)
DOI: 10.1126/sciadv.1500825

"Transverse Acoustic Impedance of Superfluid ³He B Phase in Weak Magnetic Fields"
K. Akiyama, M. Wasai, M. Mashino, T. Nakao, S. Murakawa, R. Nomura, and Y. Okuda
Journal of the Physical Society of Japan 84, 065001-1-2 (May. 2015)
DOI: 10.7566/JPSJ.84.065001

"Spin-Dependent Acoustic Response in the nonunitary A₁ and A₂ Phases of Superfluid ³He under High Magnetic Fields"
S. Murakawa, A. Yamaguchi, M. Arai, M. Wasai, Y. Aoki, H. Ishimoto, R. Nomura, Y. Okuda, Y. Nagato, S. Higashitani, and K. Nagai
Physical Review Letters 114, 105304-1-4 (Mar. 2015)
DOI: 10.1103/PhysRevLett.114.105304

"Falling ⁴He Crystals in Superfluid"
R. Nomura, T. Yoshida, A. Tachiki, and Y. Okuda
New Journal of Physics 16. 113022-1-9 (Nov. 2014)
DOI: 10.1088/1367-2630/16/11/113022

"Surface Majorana Cone of the Topological Superfluid ³He B phase"
R. Nomura, S. Murakawa, M. Wasai, K. Akiyama, T. Nakao, and Y. Okuda
Physics E 55, 42-47 (Jan. 2014)
DOI: 10.1016/j.physe.2013.06.006

"Thermal and Quantum Nucleation of ⁴He Crystals in Aerogel"
H. Matsuda, A. Ochi, R. Isozaki, R. Masumoto, R. Nomura, and Y. Okuda
Physical Review E 87, 030401(R)-1-4 (Mar. 2013)
DOI: 10.1103/PhysRevE.87.030401

"Ripening of Splashed ⁴He Crystals by Acoustic Waves with and without Gravity"
T. Takahashi, H. Ohuchi, R. Nomura, and Y. Okuda
New Journal of Physics 14, 123023-1-11 (Dec. 2012).
DOI: 10.1088/1367-2630/14/12/123023

"Surface Andreev bound states of superfluid ³He and Majorana Fermions"
Y. Okuda and R. Nomura
Journal of Physics: Condensed Matter 24, 343201-1-19 (Aug. 2012). Topical Review
DOI: 10.1088/0953-8984/24/34/343201

"Strong suppression of the Kosterlitz-Thouless transition in a ⁴He film under high pressure"
S. Murakawa, M. Wasai, K. Akiyama, Y. Wada, Y. Tamura, R. Nomura and Y. Okuda
Physical Review Letters 108, 025302-1-4 (Jan. 2012).
DOI: 10.1103/PhysRevLett.108.025302

"Surface Majorana Cone of the Superfluid ³He B Phase"
S. Murakawa, Y. Wada, Y. Tamura, M. Wasai, M. Saitoh, Y. Aoki, R. Nomura, Y. Okuda, Y. Nagato, M. Yamamoto, S. Higashitani, and K. Nagai
Journal of the Physical Society of Japan 80, 013602-1-4 (Dec. 2011).
DOI: 10.1143/JPSJ.80.013602

"New anomaly in the transverse acoustic impedance of superfluid ³He-B with a wall coated by several layers of ⁴He"
S. Murakawa, Y. Tamura, Y. Wada, M. Wasai, M. Saitoh, Y. Aoki, R. Nomura, Y. Okuda, Y. Nagato,M. Yamamoto, S. Higashitani, and K. Nagai,
Physical Review Letters 103, 155301-1-4 (Oct. 2009).
DOI: 10.1103/PhysRevLett.103.155301

"Broadening of the surface Andreev bound states band of superfluid ³He-B on a partially specular wall"
Y. Wada, S. Murakawa, Y. Tamura, M. Saitoh, Y. Aoki, R. Nomura, and Y. Okuda,
Physical Review B 78, 214516-1-5 (Dec. 2008).
DOI: 10.1103/PhysRevB.78.214516

"Competition between thermal fluctuations and disorder in the crystallization of ⁴He in aerogel"
R. Nomura, A. Osawa, T. Mimori, K. Ueno, H. Kato, and Y. Okuda,
Physical Review Letters 101, 175703-1-4 (Oct. 2008).
DOI: 10.1103/PhysRevLett.101.175703

"Observation of Surface Andreev Bound States of Superfluid ³He by Transverse Acoustic Impedance Measurements"
Y. Aoki, Y. Wada, M. Saitoh, R. Nomura, Y. Okuda, Y. Nagato, M. Yamamoto, S. Higashitani, and K. Nagai,
Physical Review Letters 95, 075301-1-4 (Aug. 2005).
DOI: 10.1103/PhysRevLett.95.075301

"Interface Motion and Nucleation of Solid Helium-4 Induced by Acoustic Waves"
R. Nomura, Y. Suzuki, S. Kimura, and Y. Okuda,
Physical Review Letters 90, 075301-1-4 (Feb. 2003).
DOI: 10.1103/PhysRevLett.90.075301