arXiv subjects

Yu-Ping Lin

Publications and source records attributed to Yu-Ping Lin.

At least 19 recordsLinked to original sources

arXiv2026

Shiba duality and $\eta$-altermagnetism: Pairing and charge orders in bipartite attractive Hubbard models

We show that Shiba duality maps the altermagnetic principle of momentum-dependent band splitting from spin to $\eta$-pseudospin, defining $\eta$-altermagnetism ($\eta$-ALM) as a Bogoliubov-de Gennes (BdG) counterpart of ALM in pairing and charge orders. In half-filled pure Hubbard models on bipartite lattices, the duality relates repulsion-driven antiferromagnetism (AFM) to attraction-driven $\eta$-AFM with uniform singlet pairing and staggered charge-density modulation. In the BdG bands, the Shiba-dual parity-time-reversal $\mathcal{\tilde{P}}\mathcal{\tilde{T}}$ symmetry protects a Kramers degeneracy of $\eta$-pseudospin. Anisotropic second-neighbor hopping breaks this degeneracy and generates $\eta$-ALM. Odd-parity $\eta$-ALM shows $\eta$-pseudospin splitting, whereas even-parity $\eta$-ALM has spin-$\eta$-locked splitting. Hartree-Fock-Bogoliubov computations on checkerboard and honeycomb lattices find $\eta$-ALMs with $p$-, $d$-, and $f$-wave splitting structures. Possible generalizations and experimental probes are discussed.

cond-mat.str-el↗

arXiv2025

Global-scale quantum networking using hybrid-channel quantum repeaters with relays based on a chain of balloons

Global-scale entanglement distribution has been a formidable challenge due to the unavoidable losses in communication channels. Here, we propose a novel backbone channel for quantum network based on balloon-based aerial relays. We demonstrate for the first time that the atmospheric disturbances in balloon-based channels can be almost eliminated through optimizing beam waist positions and employing a series of adaptive optics systems, which boosts the channel efficiency to -21 dB over a 10,000 km distance, outperforming satellite-based relays by 12 dB with same device parameters. We then propose a global-scale quantum networking scheme based on hybrid-channel quantum repeaters that combine ground-based quantum repeaters and balloon-based aerial relays. Servers are interconnected globally via a chain of balloons, while clients link to local servers through fiber connections, facilitating rapid client switching and network scalability. Our simulations, employing state-of-the-art Eu$^{3+}$:Y$_2$SiO$_5$ quantum memories and mature entanglement sources based on spontaneous parametric down-conversion, demonstrate an entanglement distribution rate in the sub-Hertz range between clients separated by 10,000 km. This approach offers a practical path toward global quantum networking in the near future.

quant-ph↗

arXiv2025

Odd-parity altermagnetism through sublattice currents: From Haldane-Hubbard model to general bipartite lattices

We propose the sublattice currents in a compensated collinear magnetic system as a feasible route to odd-parity altermagnetism (ALM), where nonrelativistic collinear spin splitting occurs in the bands as an odd function of momentum. In contrast to previously classified ALMs, the sublattice currents break the time-reversal symmetry in the nonmagnetic crystal structure and allow for such odd-parity spin splitting. A representative example is the Haldane-Hubbard model at half filling. Although the compensated collinear magnetic ground state was previously recognized as antiferromagnetism, we show that it is actually an odd-parity ALM. Interestingly, its topological version serves as an example of an ALM Chern insulator. We further generalize the Haldane-Hubbard model to common two- and three-dimensional bipartite lattices. With spin splitting allowed by sublattice currents, the compensated collinear magnetic ground states at half filling are generally odd-parity ALM.

cond-mat.str-el↗

arXiv2024

Ultrafast optical control of charge orders in kagome metals

We show that ultrafast optical pump pulses provide effective control over charge orders in the kagome metals $A$V$_3$Sb$_5$ with $A=$ K, Rb, and Cs. Starting from the real charge density waves (rCDWs) at the $p$-type Van Hove singularity, we conduct a thorough analysis of the post-pump dynamics by time-dependent Hartree-Fock theory. Our analysis uncovers distinct dynamical phenomena under linearly and circularly polarized pumps. Linearly polarized pumps induce directional preferences in the rCDWs, accompanied by an enhancement in the flat band. Unexpectedly, charge nematicity also emerges and receives maximal enhancement at a resonant pump frequency, which we understand with a Rabi-oscillation-like model. On the other hand, circularly polarized pumps suppress the rCDWs uniformly and triggers imaginary CDWs (iCDWs) with charge loop currents. Our results can be directly compared to the pump-probe experiments on the kagome metals $A$V$_3$Sb$_5$.

cond-mat.str-el↗

arXiv2024

Sublattice polarization from destructive interference on common lattices

We show that sublattice-polarized states (SLPSs) appear ubiquitously on the common lattices. We first establish the destructive-interference (DI) scenario for the SLPSs, which is systematized by a point-group-symmetry interpretation. The examples on common one-, two-, and three-dimensional lattices are then demonstrated. We also deduce the symmetry-protected robustness of SLPSs against further-neighbor hoppings. Moreover, the DI scenario can be generalized to the multi-SLP. The important effects on interaction-driven phases are studied by Hartree-Fock analysis.

cond-mat.mes-hall↗

arXiv2023

Pair-breaking scattering interference as a mechanism for superconducting gap modulation

We propose the ``pair-breaking scattering interference" as a general source of coherence peak modulations in superconductors. Assuming this mechanism, we present a simple physical picture for the coherence peak modulations in overdoped cuprate Bi$_2$Sr$_2$Ca$_2$Cu$_3$O$_{10+\delta}$ (Bi-2223), ferromagnetic iron pnictide EuRbFe$_4$As$_4$ (Eu-1144), and kagome metals $A$V$_3$Sb$_5$ ($A=$ K, Rb, and Cs). Specifically, we explain the wavevectors, the particle-hole symmetry, and the dependence on the internal or external Zeeman-field of the coherence peak modulations. This work is intended as a cautious reminder to the scientific community when asserting the existence of a pair density wave phenomenon in the absence of tunneling conductance modulations in the normal state.

cond-mat.supr-con↗

arXiv2023

Geometric semimetals and their simulation in synthetic matter

Topological semimetals, such as the Weyl and Dirac semimetals, represent one of the most active research fields in modern condensed matter physics. The peculiar physical properties of these systems mainly originate from their underlying symmetries, emergent relativistic dispersion, and band topology. In this Letter, we present a different class of gapless systems in three dimensions, dubbed $\textit{geometric semimetals}$. These semimetals are protected by the generalized chiral and rotation symmetries, but are topologically trivial. Nevertheless, we show that their band geometry is nontrivial, as evidenced by the nonzero quantum metric trace with possible quantization. The possible realization in synthetic-matter experiments is also discussed.

cond-mat.mes-hall↗

arXiv2023

Complex magnetic and spatial symmetry breaking from correlations in kagome flat bands

We present the mean-field phase diagram of electrons in a kagome flat band with repulsive interactions. In addition to flat-band ferromagnetism, the Hartree-Fock analysis yields cascades of unconventional magnetic orders driven by onsite repulsion as filling changes. These include a series of antiferromagnetic (AFM) spin-charge stripe orders, as well as an evolution from $120^\circ$AFM to intriguing noncoplanar spin orders with tetrahedral structures. We also map out the phase diagram under extended repulsion at half and empty fillings of the flat band. To examine the possibilities beyond the mean-field level, we conduct a projective symmetry group analysis and identify the feasible $\mathbb Z_2$ spin liquids and the magnetic orders derivable from them. The theoretical phase diagrams are compared with recent experiments on FeSn and FeGe, enabling a determination of the most likely magnetic instabilities in these and similar flat-band kagome materials.

cond-mat.str-el↗

arXiv2023

Chern dartboard insulator: sub-Brillouin zone topology and skyrmion multipoles

Topology plays a crucial role in many physical systems, leading to interesting states at the surface. The paradigmatic example is the Chern number defined in the Brillouin zone that leads to the robust gapless edge states. Here we introduce the reduced Chern number, defined in subregions of the Brillouin zone (BZ), and construct a family of Chern dartboard insulators (CDIs) with quantized reduced Chern numbers in the sub-BZ (sBZ) but with trivial bulk topology. CDIs are protected by mirror symmetries and exhibit distinct pseudospin textures, including (anti)skyrmions, inside the sBZ. These CDIs host exotic gapless edge states, such as M\"{o}bius fermions and midgap corner states, and can be realized in photonic crystals. Our work opens up new possibilities for exploring sBZ topology and nontrivial surface responses in topological systems.

cond-mat.mes-hall↗

arXiv2022

Protected Gapless Edge States In Trivial Topology

Bulk-boundary correspondence serves as an important feature of the strong topological insulators, including Chern insulators and $Z_2$ topological insulators. Under nontrivial band topology, the protected gapless edge states correspond to the Wannier obstruction or Wilson-loop winding in the bulk. Recent studies show that the bulk topological features may not imply the existence of protected gapless edge states. Here we address the opposite question: Does the existence of protected gapless edge states necessarily imply the Wannier obstruction or Wilson-loop winding? We provide an example where the protected gapless edge states arise without the aforementioned bulk topological features. This trivialized topological insulator belongs to a new class of systems with non-delta-like Wannier functions. Interestingly, the gapless edge states are not protected by the crystalline symmetry; instead the protection originates from the mirror antisymmetry, a combination of chiral and mirror symmetries. Although the protected gapless edge states cannot be captured by the bulk topological features, they can be characterized by the spectral flow in the entanglement spectrum.

cond-mat.mes-hall↗

arXiv2021

Multidome superconductivity in charge density wave kagome metals

Motivated by recent experiments on the kagome metals $A\text{V}_3\text{Sb}_5$ with $A=\text{K}$, $\text{Rb}$, and $\text{Cs}$, which show a charge density wave (CDW) at $\sim100$ K and the superconductivity at $\sim1$ K, we explore the onset of the superconductivity, taking the perspective that it descends from a parent CDW. We argue that viewing the superconductivity as a weak-coupling instability of a reconstructed (by the CDW) Fermi surface naturally explains the experimentally observed 'multidome' nonmonotonic dependence on pressure, with the 'peaks' in the superconducting critical temperature being associated with the Van Hove singularities of the reconstructed Fermi surface. This 'parent-child relationship' also naturally explains the large separation of energy scales between the superconductivity and the CDW. We discuss different possible pairing mechanisms and speculate that the CDW or reconstructed Pomeranchuk fluctuations may mediate the pairing interaction.

cond-mat.str-el↗

arXiv2021

Higher-order topological insulators from $3Q$ charge bond orders on hexagonal lattices: A hint to kagome metals

We show that unconventional boundary phenomena occur in the $3Q$ charge bond orders on the hexagonal lattices. At the Van Hove singularity with three nesting momenta, $3Q$ orders can trigger a $\text{C}_6$-symmetric insulator under bond modulations. On the kagome lattice, in-gap corner states appear in the energy spectrum and carry fractional corner charge $-2e/3$. Such corner phenomena originate from the corner filling anomaly and indicate a higher-order topological insulator. The in-gap corner states are also observed on the triangular lattice. The honeycomb lattice does not support fractional corner charges, while in-gap edge states are observed. We discuss possible indications to the experimentally uncovered charge bond orders in the kagome metals $\text{AV}_3\text{Sb}_5$ with $\text{A}=\text{K},\text{Rb},\text{Cs}$. With layer stacking along the out-of-plane direction, the corner states can constitute the hinge states with fractional charge densities.

cond-mat.str-el↗

arXiv2021

Complex charge density waves at Van Hove singularity on hexagonal lattices: Haldane-model phase diagram and potential realization in kagome metals $\text{AV}_3\text{Sb}_5$

We investigate how the real and imaginary charge density waves interplay at the Van Hove singularity on the hexagonal lattices. A phenomenological analysis indicates the formation of $3Q$ complex orders at all three nesting momenta. Under a total phase condition, unequal phases at the three momenta break the rotation symmetry generally. The $3Q$ complex orders constitute a rich Haldane-model phase diagram. When effective time-reversal symmetries arise under 1-site translations, the Dirac semimetals are protected. The breakdown of these symmetries gaps the Dirac points and leads to the trivial and Chern insulator phases. These phases are deformations of purely real and imaginary orders, which exhibit trivial site and/or bond density and chiral flux orders, respectively. The exotic single-Dirac-point semimetals also appear along the gapless phase boundary. We further show that the theoretical model offers transparent interpretations of experimental observations in the kagome metals $\text{AV}_3\text{Sb}_5$ with $\text{A}=\text{K},\text{Rb},\text{Cs}$. The topological charge density waves may be identified with the complex orders in the Chern insulator phase. Meanwhile, the lower-temperature symmetry-breaking phenomena may be interpreted as the secondary orders from the complex order ground states. Our work sheds light on the nature of the topological charge density waves in the kagome metals $\text{AV}_3\text{Sb}_5$ and may offer useful indications to the experimentally observed charge orders in the future experiments.

cond-mat.str-el↗

arXiv2021

Band geometry from position-momentum duality at topological band crossings

We show that the position-momentum duality offers a transparent interpretation of the band geometry at the topological band crossings. Under this duality, the band geometry with Berry connection is dual to the free-electron motion under gauge field. This identifies the trace of quantum metric as the dual energy in momentum space. The band crossings with Berry defects thus induce the dual energy quantization in the trace of quantum metric. For the $\mathbb Z$ nodal-point and nodal-surface semimetals in three dimensions, the dual Landau level quantization occurs owing to the Berry charges. Meanwhile, the two-dimensional (2D) Dirac points exhibit the Berry vortices, leading to the quantized dual axial rotational energies. Such a quantization naturally generalizes to the three-dimensional (3D) nodal-loop semimetals, where the nodal loops host the Berry vortex lines. The $\mathbb Z_2$ monopoles bring about additional dual axial rotational energies, which originate from the links with additional nodal lines. Nontrivial band geometry generically induces finite spread in the Wannier functions. While the spread manifest quantized lower bounds from the Berry charges, logarithmic divergences occur from the Berry vortices. The band geometry at the band crossings may be probed experimentally by a periodic-drive measurement.

cond-mat.mes-hall↗

arXiv2020

Parquet renormalization group analysis of weak-coupling instabilities with multiple high-order Van Hove points inside the Brillouin zone

We analyze the weak-coupling instabilities that may arise when multiple high-order Van Hove points are present inside the Brillouin zone. The model we consider is inspired by twisted bilayer graphene, although the analysis should be more generally applicable. We employ a parquet renormalization group analysis to identify the leading weak-coupling instabilities, supplemented with a Ginzburg-Landau treatment to resolve any degeneracies. Hence we identify the leading instabilities that can occur from weak repulsion with the power-law divergent density of states. Five correlated phases are uncovered along distinct stable fixed trajectories, including $s$-wave ferromagnetism, $p$-wave chiral/helical superconductivity, $d$-wave chiral superconductivity, $f$-wave valley-polarized order, and $p$-wave polar valley-polarized order. The phase diagram is stable against band deformations which preserve the high-order Van Hove singularity.

cond-mat.str-el↗

arXiv2020

Dual Haldane sphere and quantized band geometry in chiral multifold fermions

We show that the chiral multifold fermions present a dual Haldane sphere problem in momentum space. Owing to the Berry monopole at the degenerate point, a dual Landau level emerges in the trace of quantum metric, with which a quantized geometric invariant is defined through a surface integration. We further demonstrate potential manifestations in the measurable, physical observables. With a lower bound derived for the finite spread of Wannier functions, anomalous phase coherence is identified accordingly for the flat band superconductivity. We briefly comment on the stability of these results under perturbations. Potential experimental probes of the quantum metric are also discussed.

cond-mat.mes-hall↗

arXiv2020

A framework to decipher the genetic architecture of combinations of complex diseases: applications in cardiovascular medicine

Genome-wide association studies(GWAS) have proven to be highly useful in revealing the genetic basis of complex diseases. At present, most GWAS are studies of a particular single disease diagnosis against controls. However, in practice, an individual is often affected by more than one condition/disorder. For example, patients with coronary artery disease(CAD) are often comorbid with diabetes mellitus(DM). Along a similar line, it is often clinically meaningful to study patients with one disease but without a comorbidity. For example, obese DM may have different pathophysiology from non-obese DM. Here we developed a statistical framework to uncover susceptibility variants for comorbid disorders (or a disorder without comorbidity), using GWAS summary statistics only. In essence, we mimicked a case-control GWAS in which the cases are affected with comorbidities or a disease without a relevant comorbid condition (in either case, we may consider the cases as those affected by a specific subtype of disease, as characterized by the presence or absence of comorbid conditions). We extended our methodology to deal with continuous traits with clinically meaningful categories (e.g. lipids). In addition, we illustrated how the analytic framework may be extended to more than two traits. We verified the feasibility and validity of our method by applying it to simulated scenarios and four cardiometabolic (CM) traits. We also analyzed the genes, pathways, cell-types/tissues involved in CM disease subtypes. LD-score regression analysis revealed some subtypes may indeed be biologically distinct with low genetic correlations. Further Mendelian randomization analysis found differential causal effects of different subtypes to relevant complications. We believe the findings are of both scientific and clinical value, and the proposed method may open a new avenue to analyzing GWAS data.

q-bio.GN↗

arXiv2019

Phase structure and real-time dynamics of the massive Thirring model in 1+1 dimensions using the tensor-network method

We present concluding results from our study for zero-temperature phase structure of the massive Thirring model in 1+1 dimensions with staggered regularisation. Employing the method of matrix product states, several quantities, including two types of correlators, are investigated, leading to numerical evidence of a Berezinskii-Kosterlitz-Thouless phase transition. Exploratory results for real-time dynamics pertaining to this transition, obtained using the approaches of variational uniform matrix product state and time-dependent variational principle, are also discussed.

hep-lat↗