Nuclear optical clocks, a novel type of optical clock, align well with future development trends of optical clocks. As the core material for developing solid-state nuclear optical clocks, it is important to study Th-doped crystals with comprehensive advantages for the advancement of this field. The nonlinear crystal SrB4O7 (SBO) can directly frequency double a 296.8 nm laser to generate 148.4 nm excitation light, which matches the nuclear transition band of 229Th. Meanwhile, SBO can be used as a host crystal for Th doping. This study reports the successful growth of Th-doped SBO, achieving the doping of thorium in a nonlinear oxide host. A 1-mm-thick Th:SBO crystal (1.04 & times; 1018 cm-3) retained high VUV transmittance at 148.4 nm (52.08%), only marginally lower than SBO (57.29%). Th:SBO crystal is expected to be a promising candidate for solid-state optical nuclear clocks.
The light deflection under a strong gravitational field, referred to as strong gravitational lensing, provides a powerful probe of spacetime geometry. Besides, laboratory analog models are employed to study the effects of curved spacetime and explore the design of optical devices. Here, applying the framework of analog gravity, we investigate pulse echoes from a pointlike source on two curved surfaces of revolution derived from Schwarzschild spacetime, the Flamm paraboloid, and the surface of the two-dimensional Fermat metric, and reveal the interplay between the photon sphere and the pulse. We calculate the echo response using analytical geodesic solutions and the Huygens-Fresnel principle. Particularly, when the spatial scale of pulse duration is comparable to the photon sphere, continuous echo tails appear along bright interference fringes in temporal response. Analysis in both the temporal and frequency domains reveals that these echo tails are a signature of resonance between the incoming pulse and the photon sphere. This work provides a wave-optics perspective on pulse interference and echo formation in curved geometries, offering a tabletop platform for exploring the simulation of strong gravitational lensing phenomena.
We investigate magnomechanically induced transparency in a cavity magnomechanical system with travelingfield-induced non-Hermitian coupling. The setup consists of a microwave cavity mode coupled to magnons in a single-crystal yttrium iron garnet sphere, where the magnon mode is further hybridized with a vibrational mechanical mode through magnetostrictive interaction. In the Hermitian regime, strong photon-magnon coupling generates a single transparency window in the cavity transmission, which splits into a double-window structure when the magnon is coherently dressed by the mechanical mode through magnomechanical coupling. This provides a flexible platform in which the transparency response can be engineered from single- to multi-window behavior through effective magnomechanical interaction. When the non-Hermitian coupling is introduced, the transmission and phase responses become strongly asymmetric due to the competition between coherent cavity-magnon hybridization and reservoir-mediated non-Hermitian interaction. In particular, near the balance condition between the coherent and non-Hermitian couplings, the ordinary symmetric MMIT amplitude is weakened and the transparency feature is converted into an asymmetric non-Hermitian interference profile. By tuning the cavity detuning, this asymmetric magnomechanical transparency evolves into Fano-type line shapes with strongly non-Lorentzian phase dispersion, and its evolution is further visualized in two-dimensional detuning maps. Finally, we analyze the associated group delay and show that both slow- and fast-light response can be controlled by varying the photon-magnon coupling, magnomechanical interaction, and non-Hermitian strength. These results establish non-Hermitian cavity magnomechanics as a useful platform for controlling transparency, Fano interference, and probe dispersion in hybrid magnonic systems.
Vacuum magnetic birefringence (VMB) is an effect predicted by quantum electrodynamics in which the vacuum behaves as a nonlinear optical medium and exhibits a birefringence in the presence of a magnetic field. In this work, an interferometric scheme is introduced to measure this effect by sensing the changes in the frequencies of fields stabilized to the resonances of an optical cavity. Results are presented from a prototype setup with this sensing technique implemented on a 19-m test cavity without a magnetic field. We propose using this scheme for a measurement of VMB with a 245-m-long optical cavity and a string of 24 superconducting magnets, arranged for the ALPS II experiment. In this manuscript we examine potential sources of noise in the prototype and project these results in terms of the sensitivity of the full-scale experiment.
Large, three-dimensional (3D) trapped-ion crystals offer improved sensitivity in quantum sensing protocols, and are expected to be implemented as platforms in near-future experiments. However, numerical techniques used to study the laser cooling of such crystals are inefficient as the number of ions, N, in the crystal increases. Here we develop a powerful numerical framework to simulate laser cooling of up to 105 ions stored in a Penning trap. We apply this framework to characterize and optimize the cooling of ellipsoidal 3D crystals. We document pathways to enhanced cooling based on the addition of an axial component to the potential-energy-dominated E & times; B modes. Furthermore, we observe greatly enhanced cooling of the perpendicular kinetic energy to below 1 mK in prolate ion crystals, enabling a simplified cooling beam setup for such crystals. We propose specific values of trap and laser beam parameters which lead to optimal cooling in a variety of examples. This work illustrates the feasibility of preparing large 3D crystals for high-sensitivity quantum science protocols, motivating their use in future experiments.
