71 research outputs found
Demystify the mixed-parity pairing of attractive fermions with spin-orbit coupling in optical lattice
The admixture of spin-singlet and spin-triplet pairing states in
superconductors can be typically induced by breaking spatial inversion
symmetry. Employing the {\it numerically exact} auxiliary-field Quantum Monte
Carlo method, we study such mixed-parity pairing phenomena of attractive
fermions with Rashba spin-orbit coupling (SOC) in two-dimensional optical
lattice at finite temperature. We systematically demystify the evolution of the
essential pairing structure in both singlet and triplet channels versus the
temperature, fermion filling, SOC and interaction strengths, via computing the
condensate fraction and pair wave function. Our numerical results reveal that
the singlet channel dominates in the fermion pairing and the triplet pairing
has relatively small contribution to the superfluidity for physically relevant
parameters. In contrast to the singlet channel mainly consisted of the on-site
Cooper pairs, the triplet pairing has plentiful patterns in real space with the
largest contributions from several nearest neighbors. As the SOC strengh
increases, the pairing correlation is firstly enhanced and then suppressed for
triplet pairing while it's simply weakened in singlet channel. We have also
obtained the Berezinskii-Kosterlitz-Thouless transition temperatures through
the finite-size analysis of condensate fraction. Our results can serve as
quantitative guide for future optical lattice experiments as well as accurate
benchmarks for theories and other numerical methods.Comment: 14 pages, 11+5 figure
The Hintermann-Merlini-Baxter-Wu and the infinite-coupling-limit Ashkin-Teller models
We show how the Hintermann–Merlini–Baxter–Wu model (which is a generalization of the well-known Baxter–Wu model to a general Eulerian triangulation) can be mapped onto a particular infinite-coupling-limit of the Ashkin–Teller model. We work out some mappings among these models, also including the standard and mixed Ashkin–Teller models. Finally, we compute the phase diagram of the infinite-coupling-limit Ashkin–Teller model on the square, triangular, hexagonal, and kagome lattices.The research of Y.H. and Y.D. is supported by National Nature Science Foundation of China under grants Nos. 11275185 and 10975127, and the Chinese Academy of Sciences. The work of J.L.J. was supported by the Agence Nationale de la Recherche (grant ANR-10-BLAN-0414: DIME), and the Institut Universitaire de France. The research of J.S. was supported in part by Spanish MEC grants FPA2009-08785 and MTM2011-24097 and by U.S. National Science Foundation grant PHY-0424082
Recommended from our members
Single-Cell RNA Sequencing of hESC-Derived 3D Retinal Organoids Reveals Novel Genes Regulating RPC Commitment in Early Human Retinogenesis.
The development of the mammalian retina is a complicated process involving the generation of distinct types of neurons from retinal progenitor cells (RPCs) in a spatiotemporal-specific manner. The progression of RPCs during retinogenesis includes RPC proliferation, cell-fate commitment, and specific neuronal differentiation. In this study, by performing single-cell RNA sequencing of cells isolated from human embryonic stem cell (hESC)-derived 3D retinal organoids, we successfully deconstructed the temporal progression of RPCs during early human retinogenesis. We identified two distinctive subtypes of RPCs with unique molecular profiles, namely multipotent RPCs and neurogenic RPCs. We found that genes related to the Notch and Wnt signaling pathways, as well as chromatin remodeling, were dynamically regulated during RPC commitment. Interestingly, our analysis identified that CCND1, a G1-phase cell-cycle regulator, was coexpressed with ASCL1 in a cell-cycle-independent manner. Temporally controlled overexpression of CCND1 in retinal organoids demonstrated a role for CCND1 in promoting early retinal neurogenesis. Together, our results revealed critical pathways and novel genes in early retinogenesis of humans
Establishment of a Mouse Model of Premature Ovarian Failure Using Consecutive Superovulation
Background/Aims: This study investigated the effect of consecutive superovulation on the ovaries and established a premature ovarian failure (POF) model in mice. Methods: The mouse POF model was induced by 5-15 consecutive superovulation treatments with pregnant mare serum gonadotropin (PMSG), human chorionic gonadotropin (HCG) and prostaglandin F2α (PGF2α). Normal adult mice were compared with mice displaying natural ovarian aging. The following serum biochemical parameters were measured: including follicle-stimulating hormone (FSH), luteinizing hormone (LH), progesterone (P), estradiol (E2), inhibin B (INH B), malondialdehyde (MDA), total superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels. Follicles were counted using H&E staining. Levels of 8-hydroxyguanosine (8-OhdG), 4-hydroxynonenal (4-HNE), nitrotyrosine (NTY), anti-Mullerian hormone (AMH) and CDKN2A/ p16 (p16) were detected using immunohistochemical staining. Reactive oxygen species (ROS) levels were measured using dihydroethidium (DHE) staining. Cell apoptosis was detected using an in situ TUNEL fluorescence staining assay. Levels of proteins involved in ROS-related pathways and the p16 protein were detected using Western blotting. Sod1, Sod2 and Sod3 mRNA levels were detected using quantitative polymerase chain reaction (Q-PCR). Oocyte quality was evaluated using in vitro fertilization (IVF) and zygote culture. Results: Consecutive superovulation groups presented lower P, E2, SOD, GSH-Px and INH B levels, significantly higher FSH, LH, MDA and ROS levels, and significantly fewer primordial follicles compared with the control group. Consecutive superovulation groups presented significantly increased levels of Sod2, 8-OhdG, 4-HNE, NTY, significantly increased levels of the SIRT1 and FOXO1 proteins, significantly increased levels of the senescence-associated protein p16, as well as decreased AMH, Sod1 and Sod3 levels and increased granulosa cell apoptosis compared with the control group. Conclusion: Consecutive superovulation significantly decreased ovarian function and oocyte quality and increased oxidative stress and apoptosis in the ovary via a mechanism involving the p16 and SIRT1/FOXO1 signaling pathways. These findings suggest that consecutive superovulation may be used to establish a mouse model of ovarian aging
Finite-temperature phase transition in a class of 4-state Potts antiferromagnets
We argue that the 4-state Potts antiferromagnet has a finite-temperature
phase transition on any Eulerian plane triangulation in which one sublattice
consists of vertices of degree 4. We furthermore predict the universality class
of this transition. We then present transfer-matrix and Monte Carlo data
confirming these predictions for the cases of the union-jack and bisected
hexagonal lattices.Comment: LaTeX2e/Revtex4, 5 page
Quantum interface between frequency-uncorrelated down-converted entanglement and atomic-ensemble quantum memory
Photonic entanglement source and quantum memory are two basic building blocks
of linear-optical quantum computation and long-distance quantum communication.
In the past decades, intensive researches have been carried out, and remarkable
progress, particularly based on the spontaneous parametric down-converted
(SPDC) entanglement source and atomic ensembles, has been achieved. Currently,
an important task towards scalable quantum information processing (QIP) is to
efficiently write and read entanglement generated from a SPDC source into and
out of an atomic quantum memory. Here we report the first experimental
realization of a quantum interface by building a 5 MHz frequency-uncorrelated
SPDC source and reversibly mapping the generated entangled photons into and out
of a remote optically thick cold atomic memory using electromagnetically
induced transparency. The frequency correlation between the entangled photons
is almost fully eliminated with a suitable pump pulse. The storage of a
triggered single photon with arbitrary polarization is shown to reach an
average fidelity of 92% for 200 ns storage time. Moreover,
polarization-entangled photon pairs are prepared, and one of photons is stored
in the atomic memory while the other keeps flying. The CHSH Bell's inequality
is measured and violation is clearly observed for storage time up to 1
microsecond. This demonstrates the entanglement is stored and survives during
the storage. Our work establishes a crucial element to implement scalable
all-optical QIP, and thus presents a substantial progress in quantum
information science.Comment: 28 pages, 4 figures, 1 tabl
- …