Shimpei Endo

Shimpei Endo
Tohoku University | Tohokudai · Department of Physics

PhD

About

22
Publications
1,718
Reads
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876
Citations
Citations since 2017
2 Research Items
717 Citations
2017201820192020202120222023020406080100120
2017201820192020202120222023020406080100120
2017201820192020202120222023020406080100120
2017201820192020202120222023020406080100120
Additional affiliations
April 2018 - present
Tohoku University
Position
  • Professor (Assistant)
May 2016 - March 2018
Monash University (Australia)
Position
  • Fellow
April 2014 - March 2016
Ecole Normale Supérieure de Paris
Position
  • PostDoc Position
Education
April 2011 - March 2014
The University of Tokyo
Field of study
  • Physics

Publications

Publications (22)
Article
Full-text available
Existence of the eigenvalues of the discrete-time quantum walks is deeply related to localization of the walks. We revealed, for the first time, the distributions of the eigenvalues given by the splitted generating function method (the SGF method) of the space-inhomogeneous quantum walks in one dimension we had treated in our previous studies. Espe...
Preprint
Existence of the eigenvalues of the discrete-time quantum walks is deeply related to localization of the walks. We revealed the distributions of the eigenvalues given by the splitted generating function method (the SGF method) of the quantum walks we had treated in our previous studies. In particular, we focused on two kinds of the Hadamard walk wi...
Article
This article reviews theoretical and experimental advances in Efimov physics, an array of quantum few-body and many-body phenomena arising for particles interacting via short-range resonant interactions, that is based on the appearance of a scale-invariant three-body attraction theoretically discovered by Vitaly Efimov in 1970. This three-body effe...
Article
We give exact integral expressions of the third cluster or virial coefficients of binary mixtures of ideal Bose or Fermi gases, with interspecies interactions of zero range and infinite s-wave scattering length. In general the result depends on three-body parameters Rt appearing in three-body contact conditions, because an Efimov effect is present...
Article
We consider a two-component ideal Fermi gas in an isotropic harmonic potential. Some eigenstates have a wavefunction that vanishes when two distinguishable fermions are at the same location, and would be unaffected by s-wave contact interactions between the two components. We determine the other, interaction-sensitive eigenstates, using a Faddeev a...
Article
We present an exploratory study that suggests that Efimov physics, a leading research theme in few-body quantum physics, can also induce stable many-body ground states whose building blocks are universal clusters. We identify a range of parameters in a mass-and-density-imbalanced two-species fermionic mixture for which the ground state is a gas of...
Article
Full-text available
Mixtures of polarised fermions of two different masses can form weakly-bound clusters, such as dimers and trimers, that are universally described by the scattering length between the heavy and light fermions. We use the resonating group method to investigate the low-energy scattering processes involving dimers or trimers. The method reproduces appr...
Article
Full-text available
We consider a two-component ideal Fermi gas in an isotropic harmonic potential. Some eigenstates have a wavefunction that vanishes when two distinguishable fermions are at the same location, and would be unaffected by s-wave contact interactions between the two components. We determine the other, interaction-sensitive eigenstates, using a Faddeev a...
Article
We treat a position dependent quantum walk (QW) on the line which we assign two different time-evolution operators to positive and negative parts respectively. We call the model “the two-phase QW” here, which has been expected to be a mathematical model of the topological insulator. We obtain the stationary and time-averaged limit measures related...
Article
Full-text available
Efimov physics is a leading research theme in recent few-body quantum physics. It also provides a very stimulating playground to explore novel forms of quantum matter. However, not much is known about its relevance in a many-body context. Here, we address this question in a mass-and-density imbalanced two-species fermionic mixture with a positive s...
Article
Full-text available
In the free three-dimensional space, we consider a pair of identical $\uparrow$ fermions of some species or in some internal state, and a pair of identical $\downarrow$ fermions of another species or in another state. There is a resonant $s$-wave interaction (that is of zero range and infinite scattering length) between fermions in different pairs,...
Article
Full-text available
We consider a mixture of two single-spin-state fermions with an interaction of negligible range and infinite s-wave scattering length. By varying the mass ratio $\alpha$ across $\alpha$\_c ≃ 13.6069 one can switch on-and-off the Efimov effect. We determine analytically the third cluster coefficient of the gas. We show that it is a smooth funct...
Article
Full-text available
We treat a position dependent quantum walk (QW) on the line which we assign two different quantum coins to positive and negative parts respectively. We call the model "the two-phase QW" here, which is expected to express topological insulator. We obtain stationary and time-averaged limit measures related to localization. This is the first result on...
Article
Full-text available
The low-energy spectrum of three particles interacting via nearly resonant two-body interactions in the Efimov regime is set by the so-called three-body parameter. We show that the three-body parameter is essentially determined by the zero-energy two-body correlation. As a result, we identify two classes of two-body interactions for which the three...
Article
Full-text available
We consider heavy particles immersed in a Fermi sea of light fermions, and study the interaction between the heavy particles induced by the surrounding light fermions. With the Born-Oppenheimer method, we analytically show that the induced interaction between N heavy particles vanishes for any N in the limit of high light-fermion density. The induc...
Presentation
For a system of two identical fermions and one distinguishable particle interacting via a short-range potential with a large s-wave scattering length, Efimov trimers [1] and universal trimers [2] exist in different regimes of mass ratio. These trimers have different scaling symmetry: discrete and continuous scaling symmetry. We point out the existe...
Article
Full-text available
We develop an analytical approach for calculating the scattering and bound states of two polaritons in a one-dimensional (1D) infinite array of coupled cavities, with each cavity coupled to a two-level system (TLS). In particular, we find that in such a system a contact interaction between two polaritons is induced by the nonlinearity of the Jaynes...
Article
Full-text available
We address the microscopic origin of the universal three-body parameter that fixes the spectrum of three-atom systems in the Efimov regime. We identify it with the van der Waals two-body correlation, which causes the three-atom system to deform when the three atoms come within the distance of the van der Waals length, effectively preventing them fr...
Article
Full-text available
For a system of two identical fermions and one distinguishable particle interacting via a short-range potential with a large s-wave scattering length, the Efimov trimers and Kartavtsev-Malykh trimers exist in different regimes of the mass ratio. The Efimov trimers are known to exhibit a discrete scaling invariance, while the Kartavtsev-Malykh trime...
Article
Full-text available
The zero-energy universal properties of scattering between a particle and a dimer that involves an identical particle are investigated for arbitrary scattering angular momenta. For this purpose, we derive an integral equation that generalises the Skorniakov–Ter-Martirosian equation to the case of non-zero angular momentum. As the mass ratio between...
Presentation
Three-body bound states called Efimov states are associated with remarkable features such as discrete scale invariance of their spectrum, and have attracted a lot of interest since their recent experimental realizations with ultracold atoms [1]. These states are characterized by the scattering length between particles and a short-range parameter. R...
Article
Full-text available
We propose that we can realize "tight-binding photonic bands" in metallophotonic waveguide networks, where the photonic bound states localized around the crossings of a network form a tight-binding band. The formation of bound states at the crossings is distinct from the conventional bound states at defects or virtual bound states in photonic cryst...

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