652 research outputs found
Time-reversal symmetry breaking and gapped surface states due to spontaneous emergence of new order in -wave nanoislands
We solve the Bogoliubov-de Gennes equations self-consistently for the
-wave order parameter in nanoscale -wave systems with [110] surfaces and
show that spontaneous time-reversal symmetry (TRS) breaking occurs at low
temperatures due to a spontaneously induced complex order parameter of extended
-wave symmetry. The Andreev surface bound states, which are protected by a
one-dimensional (1D) topological invariant in the presence of TRS, are gapped
by the emergence of this new order parameter. The extended -wave order
parameter is localized within a narrow region near the surfaces, which is
consistent with the fact that topological protection of the gapless Andreev
surface states is characterized by the 1D topological invariant. In this
TRS-breaking phase, not only is the complex order parameter induced, but also
the -wave order parameter itself becomes complex. Furthermore, the
disappearance of topological protection brings about novel vortex phenomena
near the surfaces. We show that vortex-antivortex pairs are formed in the
extended -wave order parameter along the surfaces if the side length of a
nanoisland or the width of an infinitely long nanoribbon is relatively large.Comment: 6 pages, 4 figures + 6 pages (supplemental material), to be published
in Phys. Rev. B Rapid communicatio
Suppressing Proton Decay in the Minimal SO(10) Model
We show that in a class of minimal supersymmetric SO(10) models which have
been found to be quite successful in predicting neutrino mixings, all proton
decay modes can be suppressed by a particular choice of Yukawa textures. This
suppression works for contributions from both left and right operators for
nucleon decay and for arbitrary \tan\beta. The required texture not only fits
all lepton and quark masses as well as CKM parameters but it also predicts
neutrino mixing parameter U_e3 and Dirac CP phase \sin|\delta_MNS| to be
0.07-0.09 and 0.3-0.7 respectively. We also discuss the relation between the
GUT symmetry breaking parameters for the origin of these textures.Comment: 7 pages, 2 figure
Competition between spin and charge polarized states in nanographene ribbons with zigzag edges
Effects of the nearest neighbor Coulomb interaction on nanographene ribbons
with zigzag edges are investigated using the extended Hubbard model within the
unrestricted Hartree-Fock approximation. The nearest Coulomb interaction
stabilizes a novel electronic state with the opposite electric charges
separated and localized along both edges, resulting in a finite electric dipole
moment pointing from one edge to the other. This charge-polarized state
competes with the peculiar spin-polarized state caused by the on-site Coulomb
interaction and is stabilized by an external electric field.Comment: 4 pages; 4 figures; accepted for publication in Phys. Rev. B; related
Web site: http://staff.aist.go.jp/k.harigaya/index_E.htm
Implementing general measurements on linear optical and solid-state qubits
We show a systematic construction for implementing general measurements on a
single qubit, including both strong (or projection) and weak measurements. We
mainly focus on linear optical qubits. The present approach is composed of
simple and feasible elements, i.e., beam splitters, wave plates, and polarizing
beam splitters. We show how the parameters characterizing the measurement
operators are controlled by the linear optical elements. We also propose a
method for the implementation of general measurements in solid-state qubits.Comment: 8 pages, 3 figure
DAT (deacylating autotransporter toxin) from Bordetella parapertussis demyristoylates Gαi GTPases and contributes to cough
The pathogenic bacteria Bordetella pertussis and Bordetella parapertussis cause pertussis (whooping cough) and pertussis-like disease, respectively, both of which are characterized by paroxysmal coughing. We previously reported that pertussis toxin (PTx), which inactivates heterotrimeric GTPases of the Gi family through ADP-ribosylation of their α subunits, causes coughing in combination with Vag8 and lipid A in B. pertussis infection. In contrast, the mechanism of cough induced by B. parapertussis, which produces Vag8 and lipopolysaccharide (LPS) containing lipid A, but not PTx, remained to be elucidated. Here, we show that a toxin we named deacylating autotransporter toxin (DAT) of B. parapertussis inactivates heterotrimeric Gi GTPases through demyristoylation of their α subunits and contributes to cough production along with Vag8 and LPS. These results indicate that DAT plays a role in B. parapertussis infection in place of PTx.Hiramatsu Y., Nishida T., Ota N., et al. DAT (deacylating autotransporter toxin) from Bordetella parapertussis demyristoylates Gαi GTPases and contributes to cough. Proceedings of the National Academy of Sciences of the United States of America 120, e2308260120 (2023); https://doi.org/10.1073/pnas.2308260120
Confidence and Backaction in the Quantum Filter Equation
We study the confidence and backaction of state reconstruction based on a
continuous weak measurement and the quantum filter equation. As a physical
example we use the traditional model of a double quantum dot being continuously
monitored by a quantum point contact. We examine the confidence of the estimate
of a state constructed from the measurement record, and the effect of
backaction of that measurement on that state. Finally, in the case of general
measurements we show that using the relative entropy as a measure of confidence
allows us to define the lower bound on the confidence as a type of quantum
discord.Comment: 9 pages, 6 figure
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