We theoretically study physics of quantum many-body (QMB) systems, in which constituents obey the laws of the quantum mechanics. Examples include electrons in solids, liquid helium, ultracold gases, and quantum computers. In QMB systems, many counter-intuitive phenomena emerge thanks to the cooperation/competition of quantum effects and interparticle interactions. Specifically, we are interested in superfluidity, superconductivity, supersolidity, Kondo effects, quantum magnetism, quantum phase transitions, non-equilibrium dynamics, many-body localization, etc.
One of the severest difficulties in theoretical analyses of QMB systems lies in the fact that the numerical cost for describing a QMB system grows in general exponentially with the size of the system. Hence, in order to perform numerical analyses of realistic experiments of a QMB system, one needs efficient theoretical/numerical methods that circumvent such exponential growth of the numerical cost. We utilize and develop several numerical methods for QMB systems, such as matrix product states, cluster mean-field theory, and truncated Wigner approximation.
In recent years, analog quantum simulation has attracted much attention as a new tool for studying QMB physics. A quantum simulator mimics complex phenomena emerging in a real material by using an artificial QMB system with high controllability, including ultracold gases and trapped ions. We strongly support development/invention of quantum simulators in some experimental groups from a theoretical standpoint.
|Research title||Program title||Sponsor||Term||Amount (K JPY)||Role|
|Development of cold-atom quantum simulators on the basis of spatio-temporal optical control at the attosecond-nanometer level and its application to quantum computations||Q-LEAP Flagship program|
|MEXT||Nov. 2019 ~ Mar. 2029||25,400||Collaborator|
|Developing innovative optical-lattice quantum simulators on the basis of high controllability of ultracold gases||CREST||JST||Oct. 2016 ~ Mar. 2022||26,200||Collaborator|
|Pioneering novel quantum many-body physics with orbital and spin degrees of freedom of ultracold gases in optical lattices||KAKENHI|
|JSPS||Jul. 2018 ~ Mar. 2023||15,000||Collaborator|
|Realizing quantum gravity with both holographic principle and ultracold gases in optical lattices||KAKENHI |
|JSPS||Apr. 2018 ~ Mar. 2021||3,300||PI|
|Novel quantum phases pioneered by ultimate control and observation of Ytterbium quantum gases||KAKENHI |
|JSPS||Jul. 2013 ~ Mar. 2018||4,000||Collaborator|
|Quantum phase transitions and non-equilibrium dynamics of one-dimensional quantum fluid in non-uniform potentials||KAKENHI KIBAN(C)||JSPS||Apr. 2013~Mar. 2016||2,900||PI|
|Dynamics of strongly correlated Bose gases in optical lattices||RIKEN SPR’s Funding||RIKEN||Apr. 2010 ~ Sep. 2012||3,000||PI|
|Realizing quantum Fermi-Pasta-Ulam recurrence with ultracold gases||KAKENHI|
|JSPS||Aug. 2010~ Mar. 2011||1,250||PI|
|Breakdown of superflow in Bose gases in optical lattices||KAKENHI|
JSPS fellow’s funding
|JSPS||Apr. 2008 ~ Mar. 2010||1,600||PI|
|Spontaneous symmetry breaking and elementary excitations in Bose-Einstein condensed systems||KAKENHI|
JSPS fellow’s funding
|JSPS||Apr. 2005 ~ Mar. 2008||2,700||PI|