KAWASHIMA
To The Group's HomepageOur group investigates fundamental problems in condensed matter physics, such as critical phenomena in quantum magnets and superfluid, based on massively parallel computation on ISSP supercomputers and "K-computer" at Kobe. For example, we are trying to find a "deconfined" critical phenimena, a new category of quantum phase transition, as a transition between Neel state and VBS state in the SU(N) Heisenberg model. Our recent computational results are in favor of the continuous transition predicted by the 1/N expansion theory, and we are planning a larger computation on K-computer for more conclusive results. In addition, the list of our research subjects includes novel quantum states and supersolids in ultra-cold atoms trapped in optical lattices, the incommensurate super-solid phase in particular, computation of entanglement spectrum of a VBS state, and developement of new methods for quantum frustrated systems based on tensor networks.
The "conventional" picture of the super solid. The deviation from a commensurate filling is responsible for the super current.
Phase diagram of the Bose-Hubbard model on the cubic lattice with the hopping constant t and the on-site repulsion U. There are the checker-board phase (CB), the superfluid phase (SF), the Mott insurator phase (MI), and the super solid phase (SS). The super-solid phase exists even at the commensurate filling.Research Subject
- Search for novel quantum phases and quantum transitions
- Numerical methods for many-body physics, such as quantum Monte Carlo techniques and tensor network methods
- Spin glasses