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We present a modeling method that incorporates full-wave electromagnetic simulations and radiation force calculations to evaluate the performance of grating chips for compact megneto-optical traps (MOTs). 

We report on progress towards a single atom, single photon source using a fiber connected optical chip. Quantum experiments with cold atoms are burdened by the complexity of the experimental apparatus. Using fiber connectorized optics and a grating MOT suitable for cooling Rb atoms we fabricate a pre-aligned device usable as a single photon source for quantum communication experiments. The device integrates a grating MOT with a single beam dipole trap produced by a fiber and GRIN lens combination. MOT atoms are loaded into the dipole trap and then used as a source of single photons which are collected by the same optical fiber. We will report on details of the fabrication of the optical chip, experimental characterization, and progress towards generating high purity single photons. 

Abstract Optical bottle beams can be used to trap atoms and small low-index particles. We introduce a figure of merit (FoM) for optical bottle beams, specifically in the context of optical traps, and use it to compare optical bottle-beam traps obtained by three different methods. Using this FoM and an optimization algorithm, we identified the optical bottle-beam traps based on a Gaussian beam illuminating a metasurface that are superior in terms of power efficiency than existing approaches. We numerically demonstrate a silicon metasurface for creating an optical bottle-beam trap. 

Abstract We designed a nanoscale light extractor (NLE) for the efficient outcoupling and beaming of broadband light emitted by shallow, negatively charged nitrogen-vacancy (NV) centers in bulk diamond. The NLE consists of a patterned silicon layer on diamond and requires no etching of the diamond surface. Our design process is based on adjoint optimization using broadband time-domain simulations and yields structures that are inherently robust to positioning and fabrication errors. Our NLE functions like a transmission antenna for the NV center, enhancing the optical power extracted from an NV center positioned 10 nm below the diamond surface by a factor of more than 35, and beaming the light into a ±30° cone in the far field. This approach to light extraction can be readily adapted to other solid-state color centers. 

We investigate diffractive grating chips that can be used as part of a magneto-optical trap (MOT) to trap both Rb and Cs atoms with a single input beam for each atom species.

 

Structural characterization of biologically formed materials is essential for understanding biological phenomena and their enviro-nment, and for generating new bio-inspired engineering concepts. For example, nacre—the inner lining of some mollusk shells—encodes local environmental conditions throughout its formation and has exceptional strength due to its nanoscale brick-and-mortar structure. This layered structure, comprising alternating transparent aragonite (CaCO₃) tablets and thinner organic polymer layers, also results in stunning interference colors. Existing methods of structural characterization of nacre rely on some form of cross-sectional analysis, such as scanning or transmission electron microscopy or polarization-dependent imaging contrast (PIC) mapping. However, these techniques are destructive and too time- and resource-intensive to analyze large sample areas. Here, we present an all-optical, rapid, and nondestructive imaging technique—hyperspectral interference tomography (HIT)—to spatially map the structural parameters of nacre and other disordered layered materials. We combined hyperspectral imaging with optical-interference modeling to infer the mean tablet thickness and its disorder in nacre across entire mollusk shells from red and rainbow abalone (Haliotis rufescensandHaliotis iris) at various stages of development. We observed that in red abalone, unexpectedly, nacre tablet thickness decreases with age of the mollusk, despite roughly similar appearance of nacre at all ages and positions in the shell. Our rapid, inexpensive, and nondestructive method can be readily applied to in-field studies.

 

We describe recent work towards a fully-integrated single-photon source based on the use of single atoms captured from a grating magneto-optical trap (GMOT). Single Rb atoms from a ber-coupled GMOT will be loaded into an optical dipole trap formed by light from an integrated polarization-maintaining (PM) ber. Trapped single atoms will be excited to the 2P1/2 state using resonant light. The resulting single-photon fluorescence will be collected through the same PM ber as is used for trapping, and routed to further experiments. We describe progress towards an intermediate imple- mentation incorporating integrated optical bers and free space light sources. The completed, fully-integrated single-photon source will have numerous applications in quantum communications and quantum information processing, and particularly in improvement of the performance of quantum key distribution systems. 

Thermal emission is the process by which all objects at nonzero temperatures emit light and is well described by the Planck, Kirchhoff, and Stefan–Boltzmann laws. For most solids, the thermally emitted power increases monotonically with temperature in a one-to-one relationship that enables applications such as infrared imaging and noncontact thermometry. Here, we demonstrated ultrathin thermal emitters that violate this one-to-one relationship via the use of samarium nickel oxide (SmNiO₃), a strongly correlated quantum material that undergoes a fully reversible, temperature-driven solid-state phase transition. The smooth and hysteresis-free nature of this unique insulator-to-metal phase transition enabled us to engineer the temperature dependence of emissivity to precisely cancel out the intrinsic blackbody profile described by the Stefan–Boltzmann law, for both heating and cooling. Our design results in temperature-independent thermally emitted power within the long-wave atmospheric transparency window (wavelengths of 8 to 14 µm), across a broad temperature range of ∼30 °C, centered around ∼120 °C. The ability to decouple temperature and thermal emission opens a gateway for controlling the visibility of objects to infrared cameras and, more broadly, opportunities for quantum materials in controlling heat transfer.