Papers

The study of quantum and classical correlations between subsystems is fundamental to understanding many-body physics. In quantum information theory, the quantum mutual information, $I(A;B)$, is a measure of correlation between the subsystems $A,B$ in a quantum state, and is defined by the means of the von Neumann entropy: $I\left(A;B\right)=S\left(\rho_{A}\right)+S\left(\rho_{B}\right)-S\left(\rho_{AB}\right)$. However, such a computation requires an exponential amount of resources. This is a defining feature of quantum systems, the infamous “curse of dimensionality” . Other measures, which are based on Rényi divergences instead of von Neumann entropy, were suggested as alternatives in a recent paper showing them to possess important theoretical features, and making them leading candidates as mutual information measures. In this work, we concentrate on the maximal Rényi divergence. This measure can be shown to be the solution of a generalized eigenvalue problem. To calculate it efficiently for a 1D state represented as a matrix product state, we develop a generalized eigenvalue version of the density matrix renormalization group algorithm. We benchmark our method for the paradigmatic XXZ chain, and show that the maximal Rényi divergence may exhibit different trends than the von Neumann mutual information.

Strain and domain engineering offer powerful routes to control phase and domain stability in ferroelectric thin films. While most studies have focused on (100)-oriented growth, the impact of lower-symmetry orientations remains underexplored. We address this gap in knowledge with first-principles based molecular dynamics simulation for the example of prototypical ferroelectric perovskites under (110) strain. Epitaxial (110) strains may indeed outperform the widely studied (100) orientation, as even modest strain values stabilize a diverse set of metastable nanoscale states with potential high functional tunability. In this regime, the films exhibit multidomain configurations with domain wall normal oriented along the clamped in-plane or the relaxed out-of-plane directions and heterophases in BaTiO$_3$ and KNbO$_3$. Besides, complex superdomain patterns and antiferroelectric-like domains are observed in PbTiO$_3$. These metastable nanoscale configurations may allow for large reversible responses.

We study a honeycomb Kondo lattice model in which Dirac conduction electrons are coupled to a spin-1/2 Kitaev quantum spin liquid. For weak Kondo coupling, the spins fractionalize into Majorana fermions comprising a gapless Dirac mode and three gapped visons. In second order perturbation theory, the Kondo coupling gives rise to local Hubbard repulsions and spin-spin interactions between conduction electrons, as well as a vertex coupling electrons to gapless Majorana fermions. We analyze the resulting low-energy field theory using a perturbative renormalization group (RG) scheme, accounting for additional density-density interactions generated under RG. At criticality, electrons decouple from Majorana fermions but all three electron interactions acquire positive values. An analysis of susceptibility exponents reveals that the fractionalized Fermi liquid becomes unstable towards antiferromagnetic order and that superconductivity is disfavored.

The liquid-vapor critical behavior of water is strongly influenced by both ionic solutes and confinement. Molecular dynamics simulations of aqueous NaCl solutions using the TIP4P/2005 water model and the Madrid-2019 ion parameters reveal a systematic increase in the liquid-vapor critical temperature and pressure with salt concentration, consistent with experimental trends. In contrast, confinement between parallel hydrophobic plates leads to a depression of the critical point. The critical temperature was determined from the Binder cumulant crossing in the NVT ensemble, using a recently developed method originally applied to an active Brownian particle system. The reliability of this approach was verified through complementary NPT simulations. We further demonstrate the pronounced sensitivity of the estimated critical point to the van der Waals cutoff distance, underscoring the importance of properly accounting for long-range interactions. Our framework, which employs and tests an adjusted subbox method, can be readily extended to other critical phenomena, including the liquid-liquid critical point of water.

Defect-based single-photon emitters (SPEs) in hexagonal boron nitride (h-BN) are promising platforms for integrated quantum photonics; however, the absence of identified emitters operating at telecom wavelengths remains a critical limitation for fiber-based quantum communication. Here, we investigate previously unexplored carbon- and silicon-based point defects in monolayer h-BN as SPE candidates using hybrid density functional theory, constrained excited-state relaxations, and a generating-function approach to photoluminescence. We compute zero-phonon-line (ZPL) energies, radiative lifetimes, Huang-Rhys (HR) factors, and photoluminescence lineshapes to screen optical performance. All defects are thermodynamically stable with negative formation energies, and five candidates exhibit moderate electron-phonon coupling (HR < 5), indicating narrow emission linewidths. These emitters span a broad spectral range from the visible to the telecom regime, including near-infrared C-based centers and, most notably, the Si2BVN defect, which is identified as the first point defect in monolayer h-BN predicted to support single-photon emission in the telecom C band (1554 nm). Vacancy-containing complexes possess spin-1/2 ground states, enabling spin-photon interfaces compatible with integrated photonic and cavity-based platforms. The combined analysis of ZPL energies, electron-phonon coupling, and radiative lifetimes provides concrete targets for experimental realization of spin-active single-photon emitters in h-BN from the visible to telecom wavelengths.

We have developed an experimental setup to simultaneously acquire magneto-transmission spectra and measure the photoconductive response. The low-temperature ($T$=4.2 K) magneto-transmission data for weakly doped InSb in the frequency range 3-15 THz and magnetic fields up to 25 T, shows that the AC conductivity is governed by the classical Drude response. Moreover, the resulting light-induced voltage in this system, consisting of thermoelectric and resistive contributions, both contain features that are related to cyclotron resonances. The frequency dependence of this resonance is in good agreement with $\mathbf{k\cdot p}$ perturbation theory and corresponds to transitions between the first and second Landau level with spin-up electrons. The obtained effective mass $m^{*}(B=0)=0.014m_{e}$, is in line with the value extracted from magneto-transmission experiments. Additionally, we can observe evidence of a fluence-dependent metal-insulator transition in the thermoelectric signal, which suggest that the electronic system becomes less sensitive to the light at higher frequencies.

We investigate the ultrafast dynamics of photo-induced non-thermal lattice disorder in a polycrystalline aluminium thin film to elucidate transient short- and long-range lattice distortions, their thermalization and electron-phonon coupling timescales. Using a high-repetition-rate 95-keV ultrafast electron diffraction setup (UED), we measured the transient dynamics for the differential scattering signal in a momentum transfer, $q$, range longer than in conventional keV UED setups. Analysis of ten Bragg and six diffuse scattering revealed a prompt increase in the mean-square displacement (MSD), indicating rapid energy transfer from the excited electronic system to the lattice. The subsequent relaxation dynamics of the elastic scattering intensities exhibit a pronounced dependence on diffraction order. Lower-order reflections relax more rapidly, whereas higher-order reflections show significantly slower relaxation or near-plateau behaviour, indicating that lattice equilibration proceeds on multiple $q$-dependent timescales. Exponential fits to the MSD dynamics reveal oscillatory residuals, indicative of coherent non-thermal lattice motion. Power spectral density analysis of these residuals uncovers coherent lattice oscillations with a fundamental frequency of $\omega_0 = 0.192$ THz, corresponding to the acoustic breathing (A$_{1g}$) mode of aluminium. Higher frequency components are also observed, consistent with coherent phonon oscillations originating from a single zero-wavevector mode populated by multiple coherent phonons. While individual phonon branches are not directly resolved, the observed dependence on the lattice plane of the relaxation behaviour and oscillatory signatures are consistent with a mode-selective lattice response and non-thermal energy redistribution as described by non-thermal lattice models.

This study presents a detailed quantum chemical investigation of the electronic and excited-state properties of syn- and anti-isomers of the borane cluster B18H22 and their sulfur-doped derivatives. Using the PB86/def2-SVP level of theory with dispersion corrections, the research examines how sulfur substitution and non-covalent interactions influence cluster stability, electronic structure, spectra, and optoelectronic potential. Comparative analysis of the syn- and anti-isomers reveals the impact of molecular conformation on frontier molecular orbitals and related energetic and photophysical properties. Sulfur doping is shown to enhance charge delocalization, stabilize excited states, and improve thermal stability, which form key factors for tunable laser applications. The inclusion of advanced dispersion correction methods proves essential for accurately capturing many-body interactions that govern electronic behavior. By elucidating the interplay between structural features, substitution patterns, and computational modeling, the work provides valuable insights into structure-property relationships critical for designing borane-based materials with tailored optoelectronic and thermal characteristics. In addition to doping and dispersion effects, functionals' effects were examined through comparison amidst various ones with different asymptotic exchange on excitation and gap energies. In summary, the computational methodology combined good DFT/Basis/dispersion set to accurately predict geometries, IR/UV spectra, NMR chemical shifts, dipole moments, polarizability and excited-state properties, thereby offering a comprehensive theoretical understanding of syn-, anti- isomers of B18H22 and its sulfur doped variants.

Polar antiferromagnetic metals have recently garnered increasing interests due to their combined traits of both ferromagnets and antiferromagnets for spintronic applications. However, the inherently incompatible nature of antiferromagnet, metallicity and polarity pose a significant challenge. We propose that charge disproportionation can lead to this novel state in negative charge transfer gap regime in molecular orbital crystal by molecular orbital analyses of first-principles DFT+$U$ electronic band structure for representative Ruddlesden-Popper bilayer perovskite oxides Sr$_3$Co$_2$O$_7$, corroborated by Density Matrix Renormalization Group calculation. Due to the negative charge transfer nature of Co$^{4+}$ and imposed by strong interlayer coupling, localized molecular orbitals stemming from the hybridization of Co $d_{z^2}$ and $d_{xz/yz}$ orbitals through the apical oxygen $p$ orbitals are preferably emergent within each bilayer unit, which develop antiferromagnetic ordering by invoking Hubbard repulsion. Charge disproportionation driven by Hund's physics, makes an occupation imbalance with broken inversion symmetry in the remaining $d_{xy}$ and $d_{x^2-y^2}$ orbitals from distinct Co atoms within the bilayer unit, resulting in the polar metallicity. Meanwhile, this charge disproportionation scenario allows consequent conducting carriers to couple with interlayer local spins via Hund's coupling, giving rise to in-plane double-exchange ferromagnetism. Our molecular orbital formulation further provides a guide towards an effective Hamiltonian for modelling the unconventional synergy of metallicity, polarity and antiferromagnetism in Sr$_3$Co$_2$O$_7$, which may be a unified framework widely applicable to double-layer Ruddlesden-Popper perovskite oxides.

In this study, we conducted a theoretical analysis of specific C36 and O@C36 Fullerene isomers, namely those with (D3h, C1, Cs, C2, D2) symmetries, in the gaseous phase using the DFT method at B3LYP/6-31G* level. We studied geometry optimizations, relative stability, atomization energies, Fermi energy, energy gap, electronic properties, electric dipole moment, polarizabilities, and thermodynamic analysis, along with IR and NMR spectra. Consistently, our findings revealed distinct properties and characteristics among different C36 fullerene isomers. The energetic order of C36 fullerene isomers was established as C36-D3h < C36-C1 < C36-Cs < C36-C2 < C36-D2, a trend unaffected by the encapsulation of oxygen. Notably, the D2 isomer displayed the smallest energy gap, indicating higher electrical conductivity compared to other isomers, while it exhibited the largest gap after encapsulation. Furthermore, we observed that the C1 (D2) isomer exhibited the largest (smallest) Electric dipole moment among the studied C36 isomers, whereas the C2 (D2) isomer demonstrated the largest Electric dipole moment among the O@C36 isomers studied. The encapsulation of oxygen in C36 isomers influenced their properties, including alterations in electronic properties, IR, and NMR chemical shifts. A detailed analysis of BSSE corrections showed the tininess of their impact on the analyzed observables, such that uncorrected and BSSE-corrected calculations led to nearly identical results, confirming the robustness and reliability of the B3LYP/6-31G* approach used in this work and, eventually, in other large and rigid fullerenes systems.

We consider the barycentric version of the Bak-Sneppen model, a one-dimensional self-organized critical model that describes generalized Keynesian beauty contests with a local interaction rule. We numerically investigate the power spectral density of the fitness variable and correlation time. Through data collapse for both variables, we estimate the critical exponents. For global and local fitness variables, the power spectral density exhibits $1/f^{\alpha}$ with $0< \alpha < 2$, indicative of long-range correlations. We also investigate the cover time, defined as the duration required for the extinction or mutation of species across the entire system in the critical state of the barycentric BS model. Using finite-size scaling and extreme value theory, we analyze the statistical properties of the cover time. Our results show power-law scaling with system size for the mean, variance, mode, and peak probability. Furthermore, the cumulative probability distribution exhibits data collapse, and the associated scaling function is well described by the generalized extreme value density, closely approximating the Gumbel family.

X-ray crystallography rarely captures chemical bonding between atoms of a structure in question. Most of the time distance-based heuristics are applied to establish the pairs of bonded atoms. One class of such heuristics depends on a set of bonding radii that estimate the idealised size of each chemical element in a bond. This publication describes an unsupervised workflow for deriving a bonding radii set from crystal structure data in the Crystallography Open Database.

Semiconducting Barrier Discharges (SeBDs) generate uniform ionization waves in air at atmospheric pressure. In this work, we investigate how externally applied irradiation synchronized with the discharge can mimic photoconductive-type coupling between the plasma and the semiconductor surface. By illuminating the Si-SiO$_2$ interface with nanosecond pulsed irradiation at wavelengths from 532 nm to 1064 nm, and using fast imaging, optical emission spectroscopy, and current-voltage measurements, we demonstrate that the photoexcitation of charge carriers in silicon enhances the plasma emission and increases the reduced electric field, with no detectable change in the electrical energy. The magnitude and thresholds of these responses depend on wavelength. By comparing the SeBD to a MOS photodetector, this behaviour can be explained by the absorption length. This length determines whether carriers are photogenerated inside the depletion region at the SiO$_2$-Si interface, where they are efficiently separated and undergo impact-ionization amplification, or deeper in the silicon bulk where carrier separation is weaker and free-carrier absorption diminishes the quantum efficiency. These results focus on the microscopic processes governing the plasma-semiconductor coupling and demonstrate how the optoelectronic properties of silicon can influence surface ionization waves.

We show that the minimal mean-field theory to use for calculating the pair distribution functions $g_{\sigma\sigma'}(\vec{r},\vec{r}\,')$ of a spatially homogeneous, unpolarized spin-1/2 superfluid Fermi gas is not the ordinary static BCS theory, but the linearized time-dependent BCS theory implemented via the fluctuation-dissipation theorem. Indeed, the former completely ignores the acoustic excitation branch - the phonons - of the superfluid, while the latter explicitly takes it into account, as well as the quantum fluctuations induced by the broken-pair continuum. Unlike the first, the second theory (i) reflects the effect of these collective excitations on the system's equation of state, including at zero temperature, (ii) allows the function $g_{\uparrow\downarrow}(\vec{r},\vec{r}\,')$ to go at sufficiently large distances strictly below its asymptotic value $(\rho/2)^2$ where $\rho$ is the gas density, as expected according to the quantum hydrodynamics of Landau and Khalatnikov at low temperatures, and (iii) predicts in the function $g_{\uparrow\uparrow}(\vec{r},\vec{r}\,')$ at short distances subdominant contributions $|\vec{r}-\vec{r}\,'|^2\ln|\vec{r}-\vec{r}\,'|$ in 3D and $|\vec{r}-\vec{r}\,'|^2\ln(-\ln|\vec{r}-\vec{r}\,'|)$ in 2D, alongside the dominant contributions $|\vec{r}-\vec{r}\,'|$ in 3D and $|\vec{r}-\vec{r}\,'|^2\ln|\vec{r}-\vec{r}\,'|$ in 2D already present in static BCS theory but with a lower coefficient. This discussion is relevant to the recent theoretical work of Obeso-Jureidini and Romero-Rochin, and to the ongoing experiments on cold atomic gases at ENS and MIT.

We investigated the magnetoelastic properties of a GdRu$_2$Si$_2$ single crystal under a magnetic field applied along the crystallographic [001] and [110] directions. We report a series of strong anomalies in the sound velocity that is consistent with the complex phase diagram reported previously for this compound. In particular, in our study we focus on the recently identified magnetic phase in the high-temperature region. We show that while this phase is easily destroyed for magnetic fields applied along [001], it is rather stable for fields along [110]. Furthermore, we introduce a Landau theory and a microscopic toy model describing the elastic response at zero field. We reproduce qualitatively the observed anomalies for different acoustic modes, which allows us to propose a magnetic structure for this new high-temperature phase.

We investigate the critical behavior of a family of $\mathbb{Z}_2$-symmetric scalar field theories on the Bethe lattice (the tree limit of regular hyperbolic tessellations) using both the non-perturbative Functional Renormalization Group and lattice perturbation theory. The family is indexed by the parameter $\zeta \in (0,1]$, which determines the range of the theory via the kinetic term constructed from the graph Laplacian raised to the power $\zeta$. Specifically, $\zeta=1$ is the short-range theory, while $0<\zeta<1$ defines the long-range model. Due to the hyperbolic nature of Bethe lattices, the Laplacian lacks a zero mode and exhibits a spectral gap. We find that upon closing this spectral gap by a modification of the Laplacian, the scalar field theories exhibit novel critical behavior in the form of non-trivial fixed points with critical exponents governed by $\zeta$ and the spectral dimension $d_s=3$. In particular, our analysis indicates the presence of a Wilson-Fisher fixed point for the short range $\zeta =1$ theory. In contrast, the nearest-neighbor Ising model on the Bethe lattice is known to exhibit mean-field critical exponents. To the best of our knowledge, this work provides the first evidence that a scalar $\phi^4$ theory and the discrete Ising model on the same underlying lattice may lie in distinct universality classes.

Generative AI models, such as score-based diffusion models, have recently advanced the field of computational materials science by enabling the generation of new materials with desired properties. In addition, these models could also be leveraged to reconstruct crystal structures for which partial information is available. One relevant example is the reliable determination of atomic positions occupied by hydrogen atoms in hydrogen-containing crystalline materials. While crucial to the analysis and prediction of many materials properties, the identification of hydrogen positions can however be difficult and expensive, as it is challenging in X-ray scattering experiments and often requires dedicated neutron scattering measurements. As a consequence, inorganic crystallographic databases frequently report lattice structures where hydrogen atoms have been either omitted or inserted with heuristics or by chemical intuition. Here, we combine diffusion models from the field of materials science with techniques originally developed in computer vision for image inpainting. We present how this knowledge transfer across domains enables a much faster and more accurate completion of host structures, compared to unconditioned diffusion models or previous approaches solely based on DFT. Overall, our approach exceeds a success rate of 97% in terms of finding a structural match or predicting a more stable configuration than the initial reference, when starting both from structures that were already relaxed with DFT, or directly from the experimentally determined host structures.

Van der Waals magnets are attracting a lot of attention for their potential integration in spintronic and magnonic technologies. CrSBr is an A-type antiferromagnet that shows a coupling between its electronic band structure and magnetic properties. This property is appealing for applications and it also offers the possibility to investigate magnetic ground states and GHz magnons using visible optics techniques. Using Raman scattering and (magneto)-optical experiments, we describe the magnetic and optical properties of alloys of CrSBr$_{(1-x)}$Cl$_x$ with $x<0.46$. Similar to CrSBr, these alloys are direct band gap semiconductors with a coupling of their electronic and magnetic properties. Exciton energies evolve weakly with composition and we describe the large changes in the saturation magnetic fields and their implications on the magnetic properties. We show that both the interlayer magnetic exchange and electronic interactions are modified by the halogen mixing, offering the possibility to tune magnon energies with alloy composition.

We demonstrate photonic control of radiative heat transport in nanoscale networks through phase-controlled interference between elastic and inelastic Floquet scattering channels induced by temporal permittivity modulation. Relative modulation phases select constructive or destructive interference, enabling directional thermal-photon currents and heat splitting even at thermal equilibrium. Modulation amplitude and frequency further tune the enhancement, suppression and redistribution of energy flow. This interference-based mechanism enables thermal routing and logic operations and provides a general platform for reconfigurable photonic heat management at the nanoscale.

In applications where multiple optimal solutions are needed, transverse-field quantum annealing (QA) is known to sample degenerate ground states in a strongly biased manner. Despite extensive empirical observations, it remains unclear which features of degenerate ground states are preferentially sampled and why by QA. Here we analyze the final states using degenerate perturbation theory to characterize the preference among them. In this analysis, the adjacency matrix of the graph composed by the ground states naturally emerges, and we can predict the eigenvector centralities (one of the node centralities) are related to the probabilities of these states. We verify this prediction on toy models where degeneracy is lifted at first and second order, and we show that second-order weights encode local barrier information, relating sampling fairness to the flatness of the local energy landscape. Finally, this perspective suggests two practical routes toward fair sampling – promoting connectivity of the graph and reducing heterogeneity of centralities – and we illustrate consistency with higher-order drivers and minor-embedding transformations.

A governing equation for the granular temperature of flows past the jamming point is proposed and validated term-by-term with discrete element simulation. We measure and construct models for transport coefficients that do not diverge near the jamming fraction. As a limiting case of our equation, we derive the granular fluidity equation and find disagreement between the preexisting parametrizations of nonlocal granular fluidity, extended kinetic theory, and our discrete element simulations that is resolved by our continuum model.

Here we have experimentally demonstrated spin-correlation-driven ferroelectric quantum criticality in a prototype quantum spin-liquid system, Ba3CuSb2O9, a quantum phenomenon rarely observed. The dielectric constant follows a clear T2 scaling, showing that the material behaves as a quantum paraelectric without developing ferroelectric order. Magnetically, the system avoids long-range order down to 1.8 K and instead displays a T3/2 dependence in its inverse susceptibility, a hallmark of antiferromagnetic quantum critical fluctuations. Together with known spin-orbital-lattice entanglement in this compound, these signatures point to a strong interplay between spin dynamics and the polar lattice. Our pioneering work places this perovskite spin-liquid family at the forefront of this domain and suggest the flexibility of this family in a suitable environment by tuning chemical/ external pressure.

The square-lattice $J_1$-$J_2$ transverse-field (TF) Ising model was investigated with the exact diagonalization (ED) method. In order to analyze the TF-driven phase transition, we applied the longitudinal-field fidelity susceptibility $\chi^{(h)}_F$, which is readily evaluated via the ED scheme. Here, the longitudinal field couples with the absolute value of the magnetic moment $|M|$ rather than the raw $M$ so that the remedied fidelity susceptibility exhibits a peak around the critical point; note that the spontaneous magnetization does not appear for the finite-size systems. As a preliminary survey, the modified fidelity susceptibility $\chi^{(h)}_F$ is applied to the analysis of criticality for $J_2=0$, where a number of preceding results are available. Thereby, properly scaling the distance from the multi-criticality, $\eta=0.5-J_2$, the $\chi^{(h)}_F$ data were cast into the crossover-scaling formula, and the multi-critical exponent for $\chi_F^{(h)}$ is estimated. The result is cross-checked by the numerically evaluated $\beta$-function behavior.

Recent years have witnessed the emergence of spin supersolids in frustrated quantum magnets, establishing a material-based platform for supersolidity beyond its original context in solid helium. A spin supersolid is characterized by the coexistence of longitudinal spin order that breaks lattice translational symmetry and transverse spin order associated with the spontaneous breaking of the spin U(1) symmetry. Extensive experimental investigations, together with advanced numerical studies, have now revealed a coherent and internally consistent picture of these phases, substantially deepening our understanding of supersolidity in quantum magnetic materials. Beyond their fundamental interest as exotic quantum states, potential applications in highly efficient demagnetization cooling have been supported by a giant magnetocaloric effect observed in candidate materials. Moreover, the possible dissipationless spin supercurrents could open promising perspectives for spin transport and spintronic applications. This review summarizes recent progress on emergent spin supersolids in frustrated triangular-lattice quantum antiferromagnets, surveys experimental evidence from thermodynamic and spectroscopic measurements, and compares these results with theoretical studies of minimal models addressing global phase diagrams, ground state properties, and collective excitations. In addition, this review discusses characteristic spin-transport phenomena and outlines future directions for exploring spin supersolids as functional quantum materials.

Exceptional points (EPs), ubiquitous non-Hermitian degeneracies, are central features in band structures where non-Hermitian Fermi arcs connect EPs and eigenvalue knots encircle them. Under open boundary conditions (OBCs), non-Hermitian skin effects enforce complex momenta and yield non-Bloch band structures, introducing EPs unique to OBCs whose origins depend on boundary-driven mechanisms. Here, we reveal both theoretically and experimentally that geometry itself can induce such non-Bloch EPs in a reciprocal non-Hermitian Lieb lattice supporting geometry-dependent skin effects. By analyzing non-Bloch band structures, we find that geometry-induced EPs correspond to saddle points rather than branch points. Branch points, even while carrying OBC eigenenergies, do not yield EPs but manifest as Whitney cusps, a characteristic type of geometric singularity, and Fermi arcs connecting them remain crucial in determining eigenvalue knots. Our measurements of these knots confirm that geometry-induced EPs are detached from the branch points of Fermi arcs, contrasting with their unified counterparts in Bloch systems. Our results establish geometry as an additional degree of freedom for engineering EP-based devices and reveal its fundamental role in shaping non-Bloch band structures.

The mean free path of photocarriers is a crucial parameter for material design, device optimization, and new optoelectronics applications. Currently, this parameter remains unknown for many materials, and experimental means available for its measurement are considerably lacking. Meanwhile, it remains an unclear issue whether the mean free path of the photogenerated high-energy hot carriers is significantly different from that of the localequilibrium-state carriers near the Fermi surface or around the band edge. Based on the concept of transient grating Fourier transform and utilizing a virtual lock-in amplification technique, we proposed and demonstrated an efficient experimental technique for measuring the mean free path of photocarriers. This method has facilitated direct observation of the photocarrier transport behavior across the transition between diffusive and ballistic motion, from which we surprisingly find that the mean free path of photogenerated hot carriers in Silicon membrane and GaAs quantum well can reach micron scale, more than an order of magnitude larger compared to the electrically-measured one. This work provides new ideas for characterization of photoelectronic devices under operating status and is expected to greatly enhance the understanding of the photocarrier transport process in opto-electronic or photonic materials.

The recently discovered heavy-fermion spin-triplet superconductor candidate UTe$_2$ provides a rich platform for unconventional pairing and topological phenomena. However, limited has been known about its superconducting order parameters and their evolution with control parameters, largely due to the lack of appropriate symmetry-sensitive detections. Here, we report comprehensive point-contact spectroscopy measurements of pressurized UTe$_2$ on the (0~0~1) surface. The observation of Andreev bound states strongly suggests the presence of a $p_z$ component in the superconducting order parameters. Quantitative analysis based on an extended Blonder-Tinkham-Klapwijk model unveils the superconducting order parameters with a finite odd-$k_z$ component (e.g. $B_{2u}$ or $B_{3u}$) for both ambient and pressurized UTe$_2$. Remarkably, the multiple superconducting phases can be distinguished by a single parameter $\langle \Delta_{z}\rangle/\langle\Delta_{x(y)}\rangle$, the relative weight between the $p_z$-wave and $p_{x(y)}$-wave pairings. These findings place stringent constraints on the pairing symmetry and provide essential spectroscopic signatures for distinguishing pressure-induced multiple superconducting phases in UTe$_2$.

Transition-metal trichalcogenides distinguish themselves from other two-dimensional materials in nanoscience and materials science due to their remarkable range of intrinsic properties, including various electronic, optical, and magnetic behaviors. Here, we report a comprehensive study of superconductivity in disordered ZrTe$_{3-x}$ ($x$ = 0.2) with suppressed charge density wave. We observe a type-II bulk anisotropic superconductivity with a superconducting transition at $T_c$ = 3.59(4) \si{K}. Angle-dependent upper critical field measurements and Berezinskii-Kosterlitz-Thouless transition confirm the inherent quasi-two-dimensional nature of superconductivity in this disordered system.

The energetics and stability of dislocations, vacancies and, interstitials in the one-component plasma (OCP), where the charges interact with a log potential and move on the curved surface of a cylinder have been investigated numerically. For vacancy-interstitial pairs, the log term of the direct Coulomb attraction and the elastic displacement energy cancel exactly at long distances, resulting in a defect energy of O(1). The numerical results confirm the predicted asymptotic behavior but also identify critical distances below which pairs evolve to different forms. We have found that bound pairs of dislocations - created by adding or removing 120 degree zig-zags of particles - have a dependence on their preparation history which is not accounted for in the usual starting point of the KTHNY theory. Furthermore, isolated dislocations, whose presence disrupts crystalline order, have energies of O(1) at some values of N, the number of particles in the system, and therefore will be thermally excited, raising questions about the applicability of standard KTHNY theory to the OCP, and supporting older suggestions that there are no phase transitions at all in the two-dimensional OCP.

The experimental advances in realizing artificial spin-orbit coupling (SOC) and non-Hermitian potentials in ultracold atomic system open a new avenue for exploring their significant roles in quantum many-body physics. Here, we investigate a non-Hermitian, two-component Fermi system in a cubic lattice with Rashba SOC and complex-valued interaction arising from two-body loss. We adopt the non-Hermitian mean field theory and map out the phase diagram at zero temperature. The interplay of dissipation and on-site interaction drives a dissipation-induced phase transition from superfluid (SF) to normal phase (N). Notably, for weak interaction strengths, this leads to a reentrance of the superfluid state. The presence of SOC significantly expands the parameter regime for both the normal phase and the metastable superfluid phase(MSF). Whereas, the Zeeman field can drive the system from a conventional superfluid into a topological superfluid phase(TSF), characterized by a nontrivial topological invariant. These results enrich our knowledge of pairing superfluidity in Fermi systems.