We study the Raman response, for $B_{1g}$ and $B_{2g}$ light-polarization symmetries, of the charge density wave phase appearing in the underdoped region of cuprate superconductors. We show that the $B_{2g}$ response provides a distinctive signature of the charge order, independently of the details of the electronic structure and from the concomitant presence of a pseudogap, in sharp contrast with the behavior of the $B_{1g}$ response. This well accounts for the Raman experimental results. We then clearly identify a charge density wave energy scale, and show that its doping dependence is eventually driven by the monotonic behavior of the pseudogap. This has also been pointed out in Raman experiments, and it is suggestive of a pseudogap ruling the multiple energy scales of the exotic phases appearing in the cuprate phase diagram.

The emergence of fractonic topological phases and novel universality classes for quantum dynamics highlights the importance of dipolar symmetry in condensed matter systems. In this work, we study the properties of symmetry-breaking phases of the dipolar symmetries in fermionic models in various spatial dimensions. In such systems, fermions obtain energy dispersion through dipole condensation. Due to the nontrivial commutation between the translation symmetry and dipolar symmetry, the Goldstone modes of the dipolar condensate are strongly coupled to the dispersive fermions and naturally give rise to non-Fermi liquids at low energies. The infrared description of the dipolar symmetry-breaking phase is analogous to the well-known theory of a Fermi surface coupled to an emergent U(1) gauge field. We also discuss the crossover behavior when the dipolar symmetry is slightly broken and the cases with anisotropic dipolar conservation.

Strongly correlated phases in twisted bilayer graphene (TBG) typically arise as transitions from a state in which the system behaves as a normal metal. In such a metallic regime, electron-electron interactions usually only play a subleading role in transport measurements compared with the dominant scattering mechanism. Here, we propose and theoretically study an exception to this based on a Coulomb drag setup between two metallic TBGs separated so that they only couple through many-body interactions. We find that, by solely varying the twist angle equally in both TBGs, the drag resistivity exhibits a unique maximum as the system crosses over from a degenerate to a nondegenerate regime. When the twist angles in each TBG differ, we find an anomalous drag resistivity characterized by the appearance of multiple peaks. We show that this behavior can be related to the dependence of the rectification function on the twist angle.

We propose a series of models with inverse-square interactions, for which the ground states have an exact closed form, that describe one localized spin-$1/2$ Kondo impurity coupled to Luttinger liquids of itinerant bosons or fermions in the continuum or on a lattice. The model Hamiltonians contain two parts: a two-component Calogero-Sutherland model with an open boundary in the continuum or a long-range $t\text{−}J$-type model on the lattice, and long-range Kondo couplings between the impurity and the particles. The wave functions of the ground states in a certain basis have Jastrow product forms with powers depending on the particle statistics. It is shown that the wave functions can be expressed as chiral correlators of certain conformal field theories, which reveals that the particles are fractionalized to fully screen the Kondo impurity. This insight would be very useful in future studies on the very difficult problem of Kondo physics with interacting baths.

Kirigami, the ancient technique of paper cutting, has been successfully applied to enhance the stretchability and ductility of nanoscale graphene. However, existing experimentally realized graphene kirigami (GK) are created by introducing parallel cuts, exhibiting exceptional mechanical properties in the direction perpendicular to the cuts but brittleness in the other direction. To overcome this limitation, we propose a fractal-cut GK with rotating triangular units, enabling high stretchability and ductility in both planar directions. We investigate the deformation response of this GK under uniaxial and biaxial tension using classic molecular dynamics simulations. The results demonstrate significant improvements compared with pristine graphene, with yield and fracture strains increased by more than 3 and 5 times, respectively, under uniaxial tension and by more than 3 and 4 times, respectively, under biaxial tension. Detailed analysis shows that high stretchability is attributed to the deformation mechanism of incision rotation and flipping, while high ductility is due to the deformation mechanism of incision rotation accompanied by ligament tearing. This configured GK is expected to open avenues into the design of flexible electronic devices at the nanoscale.

A qubit driven by two incommensurate frequencies can mediate a quantized average energy current in the adiabatic limit. We show that nonadiabatic processes result in reversals of the energy current and corresponding oscillations in the net energy transferred between the drives. The oscillations are bounded but giant—much larger than the qubit energy splitting. A Landau-Zener analysis predicts that the timescale of the oscillations is exponentially large in the period of the drives. However, numerical analysis reveals that this timescale is not a monotonic function of the period and has increasing substructure as the adiabatic limit is approached. We show that this nonmonotonicity arises from interference effects between subsequent Landau-Zener transitions. Giant energy oscillations should be observable in near-term experiments with nitrogen-vacancy centers.

The quench dynamics of the Hubbard model in tilted and harmonic potentials is discussed within the semiclassical picture. Applying the fermionic truncated Wigner approximation (fTWA), the dynamics of imbalances for charge and spin degrees of freedom is analyzed and its time evolution is compared with the exact simulations in a one-dimensional lattice. Quench from charge or spin density waves is considered. We show that introduction of harmonic and spin-dependent linear potentials sufficiently validates fTWA for longer times. Such an improvement of fTWA is also obtained for the higher-order correlations in terms of quantum Fisher information for charge and spin channels. This allows us to discuss the dynamics of larger system sizes and connect our discussion to the recently introduced Stark many-body localization. In particular, we focus on a finite two-dimensional system and show that at intermediate linear potential strength, the addition of a harmonic potential and spin dependence of the tilt results in subdiffusive dynamics, similar to that of disordered systems. Moreover, for specific values of harmonic potential, we observed phase separation of ergodic and nonergodic regions in real space. The latter fact is especially important for ultracold-atom experiments in which harmonic confinement can be easily imposed, causing a significant change in relaxation times for different lattice locations.

We delineate quantum magnetism in the strongly spin-orbit coupled distorted honeycomb lattice antiferromagnet ${\mathrm{BiYbGeO}}_5$. Our magnetization and heat capacity measurements reveal that its low-temperature behavior is well described by an effective $J_{\mathrm{eff}}=\frac{1}{2}$ Kramers doublet of ${\mathrm{Yb}}^{3+}$. The ground state is nonmagnetic with a tiny spin gap. Temperature-dependent magnetic susceptibility, magnetization isotherm, and heat capacity can be modeled well assuming isolated spin dimers with anisotropic exchange interactions $J_{\mathrm{Z}}\simeq 2.6$ K and $J_{\mathrm{XY}}\simeq 1.3$ K. Heat capacity measurements backed by muon spin relaxation suggest the absence of magnetic long-range order down to at least 80 mK both in zero field and in applied fields. This sets ${\mathrm{BiYbGeO}}_5$ apart from ${\mathrm{Yb}}_2{\mathrm{Si}}_2{\mathrm{O}}_7$, with its unusual regime of magnon Bose-Einstein condensation, and suggests negligible interdimer couplings, despite only a weak structural deformation of the honeycomb lattice.

We present a straightforward approach for achieving periodic photon-magnon blockade in a hybrid optomagnonics system, wherein a single optomagnonic resonator is connected to two nanotips via chiral exceptional points (EPs). In non-Hermitian systems, the eigenvalues of the cavity optomagnonics system coalesce at the EPs. We explore the controllable generation of the photon-magnon antibunching effect by modulating the relative angle between the nanotips. Furthermore, we demonstrate that concurrent photon-magnon blockade can be realized without necessitating operation in the strong-coupling regime. In the weak-driving regime, our findings indicate that the photon-magnon blockade is more resilient to the Kerr nonlinearity of both the photon and magnon modes. Additionally, we reveal the versatile tunability of photon-magnon statistics by manipulating the system towards or away from EPs. These characteristics suggest a potential technique for adjustable single photon-magnon sources and a transition from antibunching to bunching in light switches.

Recently, vacancy-induced ferromagnetism in nanostructured materials, that in the pristine state are diamagnetic, aroused great interest among researchers due to their strong potential for the development of new technologies. In particular, vacancy-induced ferromagnetism is persistent at high temperatures, when migration of defect centers by thermal activation becomes non-negligible. For this class of materials, we developed a new and simple phenomenological model with minimal parametrization that describes very well the temperature dependence of the available experimental data. The model assumes the existence of interactions between the effective spins at vacant sites, which becomes responsible for long-range magnetic ordering. On the other side, vacancy migration produces the weakening of the exchange coupling. Our model uses a simple parametrization and very low computational resources, making this approach attractive for applications in science and technology.

Anderson localization, which originates from the wave interference between multiple-scattering paths, has been widely explored in quantum and classical systems with disordered Abelian gauge potentials. Recently, the interplay between disorder and non-Abelian gauge fields has been theoretically investigated, revealing non-Abelian Anderson localization and transition without Abelian analogy. Due to the limitation on engineering non-Abelian gauge potentials with disorder, the experimental observation of non-Abelian Anderson phenomena is still lacking. Here, we report on the experimental realization of non-Abelian Anderson localization and transition based on engineered topolectrical circuits, which are directly mapped to the quasiperiodic Aubry-André Harper model with non-Abelian gauge fields. Disorder can be suitably introduced into the effective non-Abelian coupling matrices by randomly setting the values of coupling and grounding circuit elements. In this case, different types of non-Abelian Anderson phases, including the delocalization phase, coexisting states with localized and delocalized spatial profiles, and the localization phase, can be clearly observed by measuring the site-resolved impedance spectra and voltage dynamics. Our proposal provides a flexible platform to investigate Anderson localization and transition driven by non-Abelian gauge potentials with disorder and could have potential applications in the electronic signal control.

We predict that ferromagnetic resonance in an insulating magnetic film with in-plane magnetization radiates electric fields polarized along the magnetization with opposite amplitudes at two sides of the magnetic insulator, which can be modulated strongly by adjacent superconductors. With a single superconductor adjacent to the magnetic insulator, this radiated electric field is totally reflected with a $\pi$-phase shift, which thereby vanishes at the superconductor side and causes no influence on the ferromagnetic resonance. When the magnetic insulator is sandwiched by two superconductors, this reflection becomes back and forth, so the electric field exists at both superconductors that drives the Meissner supercurrent, which in turn shifts efficiently the ferromagnetic resonance. We predict an ultrastrong coupling between magnons in the yttrium iron garnet and Cooper-pair supercurrent in NbN with a frequency shift achieving tens of percent of the bare ferromagnetic resonance.

Schwinger boson mean-field theory is a powerful approach to study frustrated magnetic systems, which allows to distinguish long-range magnetic orders from quantum spin liquid phases, where quantum fluctuations remain strong up to zero temperature. In this paper, we use this framework to study the Heisenberg model on the kagome lattice with up to third-nearest-neighbor interaction and Dzyaloshinskii-Moriya (DM) antisymmetric exchange. This model has been argued to be relevant for the description of transition metal dichalcogenide bilayers in certain parameter regimes, where spin liquids could be realized. By means of the projective symmetry group classification of possible ansätze, we study the effect of the DM interaction at first-nearest neighbor and then compute the $J_2\text{−}{J}_3$ phase diagram at different DM angles. We find a phase displaying chiral spin liquid characteristics up to spin $S=0.5$, indicating an exceptional stability of the state.

We performed ${}^{13}\mathrm{C}$ NMR measurements on $\lambda \text{−}{\left(\mathrm{BEDSe}\text{−}\mathrm{TTF}\right)}_2{\mathrm{FeCl}}_4$[BEDSe-TTF = bis(ethylenediseleno) tetrathiafulvalene] to investigate the antiferromagnetic transition in this material and evaluate the exchange interaction $J_{\pi \mathit{d}}$ between the donor molecules and ${\mathrm{FeCl}}_4^{-}$ anions. Based on the NMR spectrum and the nuclear spin-lattice relaxation rate, we determined that the antiferromagnetic transition in the donor layers occurs at 25 K. The structure of the NMR spectra in the antiferromagnetic phase resembles that of $\lambda \text{−}{\left(\mathrm{BEDSe}\text{−}\mathrm{TTF}\right)}_2{\mathrm{GaCl}}_4$. We used the angle dependence of the NMR shift in the paramagnetic phase and the experimentally determined demagnetization factor to estimate $J_{\pi \mathit{d}}$ of $\lambda {\text{-(BEDSe-TTF)}}_2{\mathrm{FeCl}}_4$ as 3.4(7) $\mathrm{T}/\mu {}_{\mathrm{B}}$ . This result shows that the $\pi \text{−}d$ interaction of $\lambda {\text{-(BEDSe-TTF)}}_2{\mathrm{FeCl}}_4$ is weaker than that of $\lambda \text{−}{\left(\mathrm{BETS}\right)}_2{\mathrm{FeCl}}_4$. The different signs of $J_{\pi \mathit{d}}$ between $\lambda \text{−}{\left(\mathrm{BEDSe}\text{−}\mathrm{TTF}\right)}_2{\mathrm{FeCl}}_4$ and $\lambda \text{−}{\left(\mathrm{BETS}\right)}_2{\mathrm{FeCl}}_4$ could be attributed to the different paths for the $\pi \text{−}d$ interaction in the two systems.

Strong long-range interaction leads to localization in a closed quantum system without disorders. Employing the exact diagonalization method, I numerically investigate thermalization and many-body localization in translational invariant quantum chains with finite Coulomb interactions. In the computational basis, excluding all trivial degeneracies, the interaction-induced localization is well demonstrated in aspects of level statistics, eigenstate expectation values, and Anderson localization on graphs constructed of many-body bases. The nature of localization for generic eigenstates is attributed to the quasidisorder from the power-law interactions, and the full localization in the Hilbert space is similar to that in the disorder case. However, due to real-space symmetries, the long-time dynamics is dominated by the degenerated eigenstates and eventually reaches homogeneity in real space. On the other hand, the entanglement entropy exhibits size dependence beyond the area law for the same reason, even deep in the localized state, indicating an incomplete localization in real space.

Despite recent intensive research on topological aspects of open quantum systems, effects of strong interactions have not been sufficiently explored. In this paper, we demonstrate that complex-valued interactions induce the Liouvillian skin effect by analyzing a one-dimensional correlated model with two-body loss. We show that, in the presence of complex-valued interactions, eigenmodes and eigenvalues of the Liouvillian strongly depend on boundary conditions. Specifically, we find that complex-valued interactions induce localization of eigenmodes of the Liouvillian around the right edge under open boundary conditions. To characterize the Liouvillian skin effect, we define the topological invariant by using the Liouvillian superoperator. Then, we numerically confirm that the topological invariant captures the Liouvillian skin effect. Furthermore, the presence of the localization of eigenmodes results in the unique dynamics observed only under open boundary conditions: particle accumulation at the right edge in transient dynamics. Our result paves the way to realize topological phenomena in open quantum systems induced by strong interactions.

The formation of persistent charge currents in mesoscopic systems remains an interesting and actual topic of condensed matter research. Here, we analyze the formation of spontaneous arising persistent currents of charged fermions in two-dimensional electron-hole ribbons on the top and bottom of a three-dimensional topological insulator. In such a device the two-dimensional Dirac fermions with opposite chiralities are spatially separated, which allows these currents to flow in the opposite directions without compensating each other. The nature of this phenomenon is based on the interference of the quasiparticle quantum waves that are scattered with asymmetric scattering phases at the lateral $np$ chiral junction and then reflected back by the external boundaries of the ribbon. As a result, quasiparticles in the ribbon are shown to be in unified electron-hole quantum states carrying the persistent current.

The present work critically investigates the interplay between light irradiation, molecular helicity, and electron hopping on spin-selective electron transmission, considering a magnetic helix as the functional element. Depending on the range of electron hopping, short-range and long-range ones, two different kinds of magnetic helices are taken into account. The common examples of these two different ranges of electron hopping are single-stranded DNA and protein molecules respectively. Each magnetic helix is subjected to a circularly polarized light which is applied perpendicular to the helix axis. The transmission spectra associated with up and down spin electrons get significantly modified, resulting in a high degree of spin polarization even when the Fermi energy is placed near the band center. The performance becomes superior with increasing the range of electron hopping. A tight-binding framework is given to describe the system, where the effect of light is incorporated through the minimal coupling approach following the Floquet-Bloch ansatz. All the results are worked out based on the standard Green's function formalism. The degree of spin polarization and its phase can be monitored selectively by means of light. To strengthen the impact of helicity, a comparative study is also made considering twist-free geometry and other twisted magnetic systems. Finally, a brief outline of the possible routes of designing magnetic helices is given, for the sake of completeness of work. Our analysis may provide some insights to achieve controlled spin-based electronic devices using different types of light-driven magnetic helices that are described beyond the conventional nearest-neighbor hopping model.

The $5f$ series dependence of itinerant-localized $5f$ states and strongly correlated electronic states has been systematically investigated in archetypical cubic compounds $A{\mathrm{Sn}}_3$ ($A=\mathrm{U}$, Np, Pu) by using a combination of the density functional theory and the embedded dynamical mean-field approach. The reproducibility of theoretical band structure and x-ray photoemission spectrum for ${\mathrm{USn}}_3$ not only guarantees the reliability of calculation, but also supports the hypothesis of enhanced localization of $5f$ states with increasing atomic series from uranium to plutonium. The suppression of valence state fluctuations, which is characterized by the strength of valence state fluctuations $\mathcal{V}\left({\mathrm{USn}}_3\right)>\mathcal{V}\left({\mathrm{NpSn}}_3\right)>\mathcal{V}\left({\mathrm{PuSn}}_3\right)$, is quantitatively described. The study reveals that these fluctuations are closely related to the itinerant nature of $5f$ states, as evidenced by significant hybridization between $5f$ states and conduction bands ($c$), as well as pronounced spectral weight around the Fermi level. Particularly, the emergence of prominent quasiparticle multiplets in ${\mathrm{PuSn}}_3$, distinct from ${\mathrm{USn}}_3$ and ${\mathrm{NpSn}}_3$, is attributed to the interplay between competing atomic eigenstates of $5f$ electrons and $5f$ valence state fluctuations. In the case of ${\mathrm{NpSn}}_3$, moderate correlation, itinerant-localized $5f$ states and significant $f\text{−}c$ hybridization contributes to the occurrence of itinerant-electron antiferromagnetism. It is proposed that a detailed understanding of the electronic structure dependence on the actinide series in $A{\mathrm{Sn}}_3$ ($A=\mathrm{U}$, Np, Pu) intermetallics compounds can provide valuable insights and promote further experimental research in this field.