The quantum behavior of light particles in solids gives rise to phenomena that cannot be captured by a classical description. We show that muon spin spectroscopy (& micro;SR), when paired with a quantum-mechanical treatment of the implanted muon, becomes a sensitive and direct probe of nuclear quantum effects. By modeling the muon as a spatially extended quantum particle, our approach captures strong anharmonic behavior. We demonstrate this in Zn-barlowite, which serves as a nontrivial test case due to its structurally complex lattice and the presence of both fluorine and hydroxyl groups. Our results establish a route for extracting nuclear quantum signatures from & micro;SR data and open different opportunities for studying light nuclei such as hydrogen and lithium in systems where quantum fluctuations shape structure and function.
As a powerful theoretical construct, the entanglement Hamiltonian (EH) encapsulates the essential entanglement properties of a quantum many-body system. From the EH, one can extract a variety of entanglement quantities, such as entanglement entropies, negativity, and the entanglement spectrum. However, its general analytical form remains largely unknown. While the Bisognano-Wichmann theorem gives an exact EH form for Lorentz-invariant field theories, its validity on lattice systems is limited, especially when Lorentz invariance is absent. In this work, we propose a general scheme based on the lattice-Bisognano-Wichmann (LBW) ansatz and multi-replica-trick quantum Monte Carlo methods to numerically reconstruct the entanglement Hamiltonian in two-dimensional systems and systematically explore its applicability to systems without translational invariance, going beyond the scope of the original Bisognano-Wichmann theorem. Various quantum phases-including gapped and gapless phases, critical points, and phases with either discrete or continuous symmetry breaking- are investigated, demonstrating the versatility of our method in reconstructing entanglement Hamiltonians. Furthermore, we find that when the entanglement boundary of a system is ordinary (i.e., free from surface anomalies), the LBW ansatz provides an accurate approximation well beyond Lorentz-invariant cases. Our work thus establishes a general framework for investigating the analytical structure of entanglement in the complex quantum many-body systems.
All-dielectric optical metasurfaces that supporting optical quasibound states in the continuum (QBICs) offer a promising platform in realization of strong light-matter coupling with monolayer transition-metal dichalcogenides (TMDCs). Such coupled systems are critical for wide range of applications in low-dimensional polaritonic physics, optoelectronic and valleytronic devices. Here, we propose a strongly coupled system between Brillouin zone folding driven quasibound states in the continuum (BZF-QBIC) mode of high-index GaP metasurfaces and excitons of monolayer WS2. By changing the height of the GaP metasurface, we observe a typical anticrossing behavior with a Rabi splitting of 38.2 meV. Simulations also show that the coupling strength is strongly dependent on both the localized electric field enhancement of the metasurface and the linewidth of the BZF-QBIC mode, there is a balance between these two factors for maximizing the coupling effect. Unlike the existing QBIC mode whose resonant wavelength is sensitive to the asymmetric parameter of the dielectric metasurface, BZF-QBICs mode exhibits an asymmetric perturbation-near-independent resonant behavior simultaneously with a high-quality factor, making it ideal for achieving strong coupling in monolayer TMDCs. This work provides a strategy for realizing monolayer TMDCs-assisted strong coupling, and facilitates potential applications in low-dimensional polaritonic devices.
We report the experimental observation of oscillations in the critical current Ic of SNS Josephson junctions as a function of in-plane magnetic field B|| (where S is Nb and N is Al above its critical temperature). Our theoretical calculations within the Ginzburg-Landau framework demonstrate that at sufficiently large B||, in-plane vortices enter the N layer, pin on the SN interface, and partially penetrate the S layer in the banks of the SNS junction. These interface vortices significantly affect the proximity-induced superconductivity in the normal weak link, leading to pronounced oscillations in the critical current Ic(B||). We also observe a superconducting diode effect of orbital origin that undergoes sign reversal with variations in the magnetic field.
Symmetry analysis is a cornerstone of modern physics, with charge- and spacetime-orientation-reversal (CRT) symmetry being a subject of particular interest. Recent research has revealed that the CRT symmetry for fermions exhibits a fractionalization distinct from the 7LC2 & times; 7LR2 & times; 7LT2 symmetry for scalar bosons. In fact, the CRT symmetry for fermions can be extended by internal symmetries such as fermion parity 7LF2 , chiral symmetry 7L chi 2 , and continuous symmetries, thereby forming a group extension of the aforementioned 7L2 direct product, and suffices to rule out bilinear mass terms. In the conventional framework, a Majorana fermion is defined by a single Dirac fermion with trivial charge conjugation. However, this definition encounters a fundamental challenge when the spacetime dimension d + 1 = 5, 6, 7 mod 8, where the real dimension of Majorana fermion (dimR chi Cl(d,0)) aligns with the real dimension of Dirac fermion (dimR psi Cl(d)), rather than being half as in other dimensions. This peculiarity necessitates the introduction of a symplectic Majorana fermion, defined by a pair of Dirac fermions with trivial charge conjugation, to account for the discrepancy. To include these two types of Majorana fermions, we embed the Majorana theory in nR and define the Majorana fermion field as a representation of the real Clifford algebra, which exhibits an eightfold Bott periodicity. Within the Hamiltonian formalism, we identify the eightfold CRT-internal symmetry groups across general spatial dimensions. In the case of Dirac fermions, the fermion field is defined as a representation of the complex Clifford algebra, which has a twofold Bott periodicity. Interestingly, we discover that the CRT-internal symmetry groups exhibit an eightfold periodicity that is distinct from that of the complex Clifford algebra. In certain dimensions where distinct mass terms can span a mass manifold, the CRT-internal symmetries can act nontrivially upon this mass manifold. Employing domain wall reduction method, we are able to elucidate the relationships between symmetries across different dimensions.
