# Shimpei EndoTohoku University | Tohokudai · Department of Physics

Shimpei Endo

PhD

## About

22

Publications

1,760

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891

Citations

Introduction

Additional affiliations

April 2018 - present

May 2016 - March 2018

April 2014 - March 2016

Education

April 2011 - March 2014

## Publications

Publications (22)

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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,...

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 Ã¢ÂÂ 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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...