221 research outputs found
Generalization of Benalcazar-Bernevig-Hughes model to arbitrary dimensions
The Benalcazar-Bernevig-Hughes (BBH) model [Science 357, 61 (2017)],
featuring bulk quadrupole moment, edge dipole moments, and corner states, is a
paradigm of both higher-order topological insulators and topological multipole
insulators. In this work, we generalize the BBH model to arbitrary dimensions
by utilizing the Clifford algebra. For the generalized BBH model, the
analytical solution of corner states can be directly constructed in a unified
way. Based on the solution of corner states and chiral symmetry analysis, we
develop a general boundary projection method to extract the boundary
Hamiltonians, which turns out to be the BBH models of lower dimension and
reveals the dimensional hierarchy
Interaction-driven topological phase diagram of twisted bilayer MoTe
Twisted bilayer MoTe is a promising platform to investigate the interplay
between topology and many-body interaction. We present a theoretical study of
its interaction-driven quantum phase diagrams based on a three-orbital model,
which can be viewed as a generalization of the Kane-Mele-Hubbard model with an
additional orbital and realistic Coulomb repulsion. We predict a cascade of
phase transitions tuned by the twist angle . At the hole filling factor
(one hole per moir\'e unit cell), the ground state can be in the
multiferroic phase with coexisting spontaneous layer polarization and
magnetism, the quantum anomalous Hall phase, and finally the topologically
trivial magnetic phases, as increases from to
. At , the ground state can have a second-order phase
transition between an antiferromagnetic phase and the quantum spin Hall phase
as passes through a critical value. The dependence of the phase
boundaries on model parameters such as the gate-to-sample distance, the
dielectric constant, and the moir\'e potential amplitude is examined. The
predicted phase diagrams can guide the search for topological phases in twisted
transition metal dichalcogenide homobilayers.Comment: 12 pages, 7 figures. Comments and Collaborations are Welcome
Braiding higher-order Majorana corner states through their spin degree of freedom
In this work, we study the spin texture of a class of higher-order
topological superconductors (HOTSC) and show how it can be used to detect and
braid Majorana corner modes (MCMs). This class of HOTSC is composed of
two-dimensional topological insulators with s-wave superconductivity and
in-plane magnetic fields, which offers advantages in experimental
implementation. The spin polarization of the MCMs in this class is
perpendicular with the applied magnetic field direction and is opposite on
intrinsic orbitals, resulting in an overall ferrimagnetic spin texture. As a
result, we find that the spin-selective Andreev reflection can be observed in a
transverse instead of parallel direction to the applied magnetic field.
Meanwhile, this spin texture leads to the gate-tunable periodic
Josephson current that performs qualitatively different behavior from the
topologically trivial -junction under rotating the in-plane magnetic
field. Meanwhile, the existence of the MCMs in this class does not depend on
the in-plane magnetic field direction. This gives rise to great advantage in
constructing all electronically controlled Majorana network for braiding, which
is confirmed through our numerical simulation. We thus provide a comprehensive
scheme for probing non-Abelian statistics in this class of HOTSCs.Comment: 6 pages, 4 figure
The statistical properties of galaxy morphological types in compact groups of Main galaxies from the SDSS Data Release 4
In order to explore the statistical properties of galaxy morphological types
in compact groups (CGs), we construct a random group sample which has the same
distributions of redshift and number of member galaxies as those of the CG
sample. It turns out that the proportion of early-type galaxies in different
redshift bins for the CG sample is statistically higher than that for random
group sample, and with growing redshift z this kind of difference becomes more
significant. This may be due to the existence of interactions and mergers
within a significant fraction of SDSS CGs. We also compare statistical results
of CGs with those of more compact groups and pairs, but do not observe as large
statistical difference as Hickson (1982)'results.Comment: 12 pages, 9 figure
Lipin1 Regulates Skeletal Muscle Differentiation through Extracellular Signal-regulated Kinase (ERK) Activation and Cyclin D Complex-Regulated Cell Cycle Withdrawal
Lipin1, an intracellular protein, plays critical roles in controlling lipid synthesis and energy metabolism through its enzymatic activity and nuclear transcriptional functions. Several mouse models of skeletal muscle wasting are associated with lipin1 mutation or altered expression. Recent human studies have suggested that children with homozygous null mutations in the LPIN1 gene suffer from rhabdomyolysis. However, the underlying pathophysiologic mechanism is still poorly understood. In the present study we examined whether lipin1 contributes to regulating muscle regeneration. We characterized the time course of skeletal muscle regeneration in lipin1-deficient fld mice after injury. We found that fld mice exhibited smaller regenerated muscle fiber cross-sectional areas compared with wild-type mice in response to injury. Our results from a series of in vitro experiments suggest that lipin1 is up-regulated and translocated to the nucleus during myoblast differentiation and plays a key role in myogenesis by regulating the cytosolic activation of ERK1/2 to form a complex and a downstream effector cyclin D3-mediated cell cycle withdrawal. Overall, our study reveals a previously unknown role of lipin1 in skeletal muscle regeneration and expands our understanding of the cellular and molecular mechanisms underlying skeletal muscle regeneration
Controllable Majorana vortex states in iron-based superconducting nanowires
There has been experimental evidence for the Majorana zero modes (MZMs) in
solid state systems, which are building blocks for potential topological
quantum computing. It is important to design devices, in which MZMs are easy to
manipulate and possess a broad topological non-trivial parameter space for
fusion and braiding. Here, we propose that the Majorana vortex states in
iron-based superconducting nanowires fulfill these desirable conditions. This
system has a radius-induced topological phase transition, giving a lower limit
to the radius of the nanowire. In the topological phase, there is only one pair
of MZMs in the nanowire over a wide range of radius, chemical potential, and
external magnetic field. The wavefunction of the MZM has a sizable distribution
at the side edge of the nanowire. This property enables one to control the
interaction of the MZMs in neighboring vortex nanowires, and paves the way for
Majorana fusion and braiding.Comment: 13 pages and 7 figure
Deterministic topological quantum gates for Majorana qubits without ancillary modes
The realization of quantum gates in topological quantum computation still
confronts significant challenges in both fundamental and practical aspects.
Here, we propose a deterministic and fully topologically protected
measurement-based scheme to realize the issue of implementing Clifford quantum
gates on the Majorana qubits. Our scheme is based on rigorous proof that the
single-qubit gate can be performed by leveraging the neighboring Majorana qubit
but not disturbing its carried quantum information, eliminating the need for
ancillary Majorana zero modes (MZMs) in topological quantum computing.
Benefiting from the ancilla-free construction, we show the minimum measurement
sequences with four steps to achieve two-qubit Clifford gates by constructing
their geometric visualization. To avoid the uncertainty of the measurement-only
strategy, we propose manipulating the MZMs in their parameter space to correct
the undesired measurement outcomes while maintaining complete topological
protection, as demonstrated in a concrete Majorana platform. Our scheme
identifies the minimal operations of measurement-based topological and
deterministic Clifford gates and offers an ancilla-free design of topological
quantum computation.Comment: 5 pages, 3 figures and appendi
- …