Quantum Condensate Research Team

Principal Investigator

PI Name Masahito Ueda
Degree Ph.D.
Title Team Leader
Brief Resume
1988 Researcher, NTT Basic Research Laboratories
1994 Associate Professor, Hiroshima University
2000 Professor, Tokyo Institute of Technology
2008 Professor, University of Tokyo (-present)
2014 Team Leader, Quantum Condensate Research Team, Quantum Information Electronics Division, RIKEN Center for Emergent Matter Science (-present)


We aim to explore physics frontiers that lie at the boarderlines between quantum physics, quantum measurement, information, thermodynamics, and machine learning. In particular, we exploit nonequilibrium open quantum physics and quantum thermodynamics by using ultracold atoms in which almost all parameters such as the interparticle interaction are tunable.

Research Fields

Physics, Engineering, Mathematics, Multidisciplinary


Cold atoms
Bose-Einstein condensates
Nonequilibrium open quantum systems
Quantum thermodynamics


Topological excitations in Bose-Einstein condensates

Bose-Einstein condensates offer a cornucopia of symmetry breaking because a rich variety of internal degrees of freedom are available depending on the atomic species. We have used these degrees of freedom to explore various aspects of symmetry breaking and topological excitations. Among them are the so-called Kibble-Zurek mechanism in which the order parameter develops singularities after some parameter of the system is suddenly quenched. Ordinary vortices and spin vortices are found to emerge. We also investigate novel topological phenomena such as knot excitations in an antiferromagnetic Bose-Einstein condensate.


Ground-state phase diagram of a spin-2 Bose-Einstein condensate (BEC). Depending on the phase, different topological excitations appear.


Masahito Ueda

Team Leader masahito.ueda[at]riken.jp

Xingyuan Zhang

Visiting Scientist


  1. L. Dabelow, and M. Ueda

    Three learning stages and accuracy-efficiency tradeoff of restricted Boltzmann machines

    Nat. Commun. 13, 5474 (2022)
  2. E. Yukawa, and M. Ueda

    Morphological Superfluid in a Nonmagnetic Spin-2 Bose-Einstein Condensate

    Phys. Rev. Lett. 124, 105301 (2020)
  3. K. Kawabata, K. Shiozaki, M. Ueda, and M. Sato

    Symmetry and Topology in Non-Hermitian Physics

    Phys. Rev. X 9, 041015 (2019)
  4. K. Kawabata, S. Higashikawa, Z. Gong, Y. Ashida, and M. Ueda

    Topological unification of time-reversal and particle-hole symmetries in non-Hermitian physics

    Nat. Commun. 10, 297 (2019)
  5. Z. Gong, Y. Ashida, K. Kawabata, K. Takasan, S. Higashikawa, and M. Ueda

    Topological Phases of Non-Hermitian Systems

    Phys. Rev. X 8, 031079 (2018)



2-1 Hirosawa, Wako, Saitama 351-0198 Japan