-
[show abstract]
[hide abstract]
ABSTRACT: We study vortex lattices in three-component BECs under rotation, where three
kinds of fractional vortices winding one of three components are present.
Unlike the cases of two-component BECs where the phases of square and
triangular lattices are present depending on the intercomponent coupling
constant and the rotation speed, we find triangular ordered "colorful" vortex
lattices where three kind of fractional vortices are placed in order without
defects, in all parameter region where the inter-component coupling g' is less
than the intra-component coupling g. When g > g' on the other hand, we find the
phase separation; In a region where one component is present, the other two
components must vanish, where we find ghost vortices in these two components
whose positions are separated. In the boundary g = g', the accidental U(3)
symmetry is present, in which case two vortices in different components are
close to each other in some regions.
04/2013;
-
[show abstract]
[hide abstract]
ABSTRACT: We exhaust all exact self-consistent solutions of complex-valued fermionic condensates in the (1+1)-dimensional Bogoliubov-de Gennes and chiral Gross-Neveu systems under uniform boundary conditions. We obtain n complex (twisted) kinks, or gray solitons, with 2n parameters corresponding to their positions and phase shifts. Each soliton can be placed at an arbitrary position while the self-consistency requires its phase shift to be quantized by π/N for N flavors.
Physical Review Letters 03/2013; 110(13):131601. · 7.37 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We study effects of the internal coherent (Rabi) coupling in vortex lattices
in two-component BECs under rotation. We find how the vortex lattices without
the Rabi coupling known before are connected to the Abrikosov lattice of
integer vortices with increasing the Rabi coupling. We find that 1) for small
Rabi couplings, fractional vortices in triangular or square lattice for small
or large inter-component coupling constitute hexamers or tetramers, namely
multi-dimer bound states made of six or four vortices, respectively, 2) these
bound states are broken into a set of dimers at intermediate Rabi couplings,
and 3) vortices change their partners in various ways depending on the
inter-component coupling to organize themselves for constituting the Abrikosov
lattice of integer vortices at strong Rabi couplings.
03/2013;
-
[show abstract]
[hide abstract]
ABSTRACT: Kelvin waves or Kelvons have been known for a long time as gapless
excitations propagating along superfluid vortices. These modes can be
interpreted as the Nambu-Goldstone excitations arising from the spontaneous
breaking of the translational symmetry. Recently a different type of gapless
excitation localized on strings -- the so-called non-Abelian mode -- attracted
much attention in high-energy physics. We discuss their relevance in condensed
matter physics. Although we failed to find exactly gapless non-Abelian modes,
non-Abelian rotational quasigapless excitations are argued to exist on the mass
vortices in the B phase of the superfluid 3He, due to the fact that the order
parameter in 3He-B is tensorial. While the U(1) rotational excitations are well
established in vortices with asymmetric cores, the non-Abelian rotational
excitations belonging to the same family were not considered. In the general
case they are coupled with the translational modes.
01/2013;
-
[show abstract]
[hide abstract]
ABSTRACT: We show theoretically that a domain-wall annihilation in two-component Bose-Einstein condensates causes tachyon condensation accompanied by spontaneous symmetry breaking in a two-dimensional subspace. Three-dimensional vortex formation from domain-wall annihilations is considered a kink formation in subspace. Numerical experiments reveal that the subspatial dynamics obey the dynamic scaling law of phase-ordering kinetics. This model is experimentally feasible and provides insights into how the extra dimensions influence subspatial phase transition in higher-dimensional space.
Physical Review Letters 12/2012; 109(24):245301. · 7.37 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In brane cosmology, the Big Bang is hypothesized to occur by the annihilation
of the brane-anti-brane pair in a collision, where the branes are
three-dimensional objects in a higher-dimensional Universe. Spontaneous
symmetry breaking accompanied by the formation of lower-dimensional topological
defects, e.g. cosmic strings, is triggered by the so-called `tachyon
condensation', where the existence of tachyons is attributable to the
instability of the brane-anti-brane system. Here, we discuss the closest
analogue of the tachyon condensation in atomic Bose-Einstein condensates. We
consider annihilation of domain walls, namely branes, in strongly segregated
two-component condensates, where one component is sandwiched by two domains of
the other component. In this system, the process of the brane annihilation can
be projected effectively as ferromagnetic ordering dynamics onto a
two-dimensional space. Based on this correspondence, three-dimensional
formation of vortices from a domain-wall annihilation is considered to be a
kink formation due to spontaneous symmetry breaking in the two-dimensional
space. We also discuss a mechanism to create a `vorton' when the sandwiched
component has a vortex string bridged between the branes. We hope that this
study motivates experimental researches to realize this exotic phenomenon of
spontaneous symmetry breaking in superfluid systems.
11/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: In the standard model, the electroweak Z-string can end on a Nambu monopole,
whose mass is calculated to be 689 GeV from the current precise experimental
data assuming the new particle with mass 125 GeV to be the Higgs boson. We
study an extension of the standard model with additional singlet and triplet
Higgs fields in the framework of N=1 supersymmetric field theory by using a
D-brane configuration in type IIA string theory. We construct a D-brane
configuration describing the electroweak symmetry breaking, and find a single
D2-brane configuration describing a Z-string and a Nambu monopole attached by a
Z-string in the standard model without an adjoint Higgs field. We further find
a single D2-brane configuration describing a composite of a 't Hooft-Polyakov
monopole and a Nambu monopole attached by a Z-string in an extended standard
model with an adjoint Higgs field. We compute the binding energy of the 't
Hooft-Polyakov and Nambu monopoles by solving a minimal surface area of a
D2-brane.
11/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: We study junctions of vortices, or boojums, at the interface between color
and hadronic superconducting/superfluid phases. This type of interface could be
present in the interior of neutron stars, where an inner core made of quark
matter in the color-flavor-locked phase is surrounded by an outer shell of
superconducting protons and superfluid neutrons. We study the fate of magnetic
(proton) and superfluid (neutron) vortices as they enter the color-flavor
locked phase. We find that proton vortices terminate on Dirac monopoles of the
massless magnetic field, and magnetic fluxes of massive gauge field spread
along the surface and are screened by surface superconducting currents. On the
other hand, three neutron vortices join at a boojum and split into three color
magnetic vortices which host confined color-magnetic monopoles when strange
quark mass is taken into account. We also present a simple numerical model of
the shape of the neutron boojum.
08/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: We successfully exhaust the complete set of exact solutions of non-Abelian
vortices in a quiver gauge theory, that is, the S[U(N) x U(N)] gauge theory
with a bi-fudamental scalar field on a hyperbolic plane with a certain
curvature, from SO(3)-invariant SU(2N) Yang-Mills instanton solutions. This
work provides, for the first time, exact non-Abelian vortex solutions. We
establish the ADHM construction for non-Abelian vortices and identify all the
moduli parameters and the complete moduli space.
07/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: There are a large number of systems characterized by a completely broken
gauge symmetry, but with an unbroken global color-flavor diagonal symmetry,
i.e., systems in the so-called color-flavor locked phase. If the gauge symmetry
breaking supports vortices, the latter develop non-Abelian orientational
zero-modes and become non-Abelian vortices, a subject of intense study in the
last several years. In this paper we consider the effects of weakly gauging the
full exact global flavor symmetry in such systems, deriving an effective
description of the light excitations in the presence of a vortex. Surprising
consequences are shown to follow. The fluctuations of the vortex orientational
modes get diffused to bulk modes through tunneling processes. When our model is
embedded in a supersymmetric theory, the vortex is still 1/2 BPS saturated, but
the vortex effective action breaks supersymmetry spontaneously.
06/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: When a color superconductor of high density QCD is rotating, superfluid
vortices are inevitably created along the rotation axis. In the color-flavor
locked phase realized at the asymptotically large chemical potential, there
appear non-Abelian vortices carrying both circulations of superfluid and color
magnetic fluxes. A family of solutions has a degeneracy characterized by the
Nambu-Goldtone modes CP2, associated with the color-flavor locked symmetry
spontaneously broken in the vicinity of the vortex. In this paper, we study
electromagnetic coupling of the non-Abelian vortices and find that the
degeneracy is removed with the induced effective potential. We obtain one
stable vortex solution and a family of metastable vortex solutions, both of
which carry ordinary magnetic fluxes in addition to color magnetic fluxes. We
discuss quantum mechanical decay of the metastable vortices by quantum
tunneling, and compare the effective potential with the other known potentials,
the quantum mechanically induced potential and the potential induced by the
strange quark mass.
06/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: The chiral Gross-Neveu model or equivalently the linearized Bogoliubov-de
Gennes equation has been mapped to the nonlinear Schr\"odinger (NLS) hierarchy
in the Ablowitz-Kaup-Newell-Segur formalism by Correa, Dunne and Plyushchay. We
derive the general expression for exact fermionic solutions for all gap
functions in the arbitrary order of the NLS hierarchy. We also find that the
energy spectrum of the n-th NLS hierarchy generally has n+1 gaps. As an
illustration, we present the self-consistent two-complex-kink solution with
four real parameters and two fermion bound states. The two kinks can be placed
at any position and have phase shifts. When the two kinks are well separated,
the fermion bound states are localized around each kink in most parameter
region. When two kinks with phase shifts close to each other are placed at
distance as short as possible, the both fermion bound states have two peaks at
the two kinks, i.e., the delocalization of the bound states occurs.
05/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: We theoretically study the vortex formation from the collision of the domain walls in phase-separated two-component Bose-Einstein
condensates. The collision process mimics the tachyon condensation for the annihilation of D-brane and anti-D-brane in string
theory. A pair annihilation leaves the quantized vortices with superflow along their core, namely superflowing cosmic strings. It is revealed that the line density and the core size of the vortices depend on the initial distance between the walls.
KeywordsBose-Einstein condensates–D-brane
Journal of Low Temperature Physics 04/2012; 162(3):243-249. · 1.19 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We demonstrate theoretically that analogues of D-branes in string theory can be realized in rotating, phase-separated, two-component
Bose-Einstein condensates and that they are observable using current experimental techniques. This study raises the possibility
of simulating D-branes in the laboratory.
KeywordsSigma Models-Solitons Monopoles and Instantons-D-branes-Spontaneous Symmetry Breaking
Journal of High Energy Physics 04/2012; 2010(11):1-12. · 5.83 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We study interfacial topological defects called boojums, a vortex ending or a connecting point of two kinds of vortex cores, in rotating two-component Bose-Einstein condensates.
First, we show that the boojum exists at a vortex ending that connects to the interface of the strongly phase-separated condensates.
Next, we study various boojums appearing between two phases characterized by different vortex structures, where the intercomponent
s-wave scattering lengths are spatially varied. Using three-dimensional simulations of the Gross-Pitaevskii equations, we reveal
the detailed structure of the boojums by visualizing its density distribution and effective superflow vorticity.
Journal of Low Temperature Physics 04/2012; 158(1):99-104. · 1.19 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The vortex partition function in 2d N = (2,2) U(N) gauge theory is derived
from the field theoretical point of view by using the moduli matrix approach.
The character for the tangent space at each moduli space fixed point is written
in terms of the moduli matrix, and then the vortex partition function is
obtained by applying the localization formula. We find that dealing with the
fermionic zero modes is crucial to obtain the vortex partition function with
the anti-fundamental and adjoint matters in addition to the fundamental chiral
multiplets. The orbifold vortex partition function is also investigated from
the field theoretical point of view.
04/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: We give a systematic method to calculate higher derivative corrections to
low-energy effective theories of solitons, which are in general non-linear
sigma models on the moduli spaces of the solitons. By applying it to the
effective theory of a single BPS non-Abelian vortex in U(N) gauge theory with N
fundamental Higgs fields, we obtain four derivative corrections to the
effective sigma model on the moduli space C \times CP^{N-1}. We compare them
with the Nambu-Goto action and the Faddeev-Skyrme model. We also show that
Yang-Mills instantons/monopoles trapped inside a non-Abelian vortex
membrane/string are not modified in the presence of higher derivative terms.
04/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: We propose a mechanism to create a vorton or three-dimensional skyrmion in
phase-separated two-component BECs with the order parameters Psi_1 and Psi_2 of
the two condensates. We consider a pair of a domain wall (brane) and an
anti-domain wall (anti-brane) stretched by vortices (strings), where the Psi_2
component with a vortex winding is sandwiched by two domains of the Psi_1
component. The vortons appear when the domain wall pair annihilates.
Experimentally, this can be realized by preparing the phase separation in the
order Psi_1, Psi_2 and Psi_1 components, where the nodal plane of a dark
soliton in Psi_1 component is filled with the Psi_2 component with vorticity.
By selectively removing the filling Psi_2 component gradually with a resonant
laser beam, the collision of the brane and anti-brane can be made, creating
vortons.
03/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: Vortex trimer is predicted in three-component Bose-Einstein condensates with
internal coherent couplings. The molecule is made by three constituent vortices
which are bounded by domain walls of the relative phases. We show that the
shape and the size of the molecule can be controlled by changing the internal
coherent couplings.
01/2012;
-
[show abstract]
[hide abstract]
ABSTRACT: Effects of mass deformations on 1/2 Bogomol'nyi-Prasad-Sommerfield (BPS)
non-Abelian vortices are studied in 4d N=2 supersymmetric U(1) \times SO(2n)
and U(1) \times USp(2n) gauge theories, with Nf=2n quark multiplets. The 2d
N=(2,2) effective worldsheet sigma models on the Hermitian symmetric spaces
SO(2n)/U(n) and USp(2n)/U(n) found recently which describe the low-energy
excitations of the orientational moduli of the vortices, are generalized to the
respective massive sigma models. The continuous vortex moduli spaces are
replaced by a finite number (2^{n-1} or 2^{n}) of vortex solutions. The 1/2 BPS
kinks connecting different vortex vacua are magnetic monopoles in the 4d
theory, trapped inside the vortex core, with total configurations being 1/4 BPS
composite states. These configurations are systematically studied within the
semi-classical regime.
08/2011;
