The control of recruitment to intertidal barnacle populations along the central California coast was examined from April to mid-October 1988. Four recruitment pulses occurred during periods of relaxation in alongshore winds and cessation of coastal upwelling. In each case recruitment ended when strong equatorward winds reappeared -and upwelling resumed. Data on SST, salinity, adjusted sea level, and satellite (AVHRR) images revealed alternating periods of onshore and offshore transport of the surface water layer. The onset of the largest recruitment pulse was associated with the advection of warm, clear, low-salinity water into the neat-shore region. This oceanic water mass also contained a different zooplankton assemblage than the water mass it replaced.

Point defects in silicon carbide are rapidly becoming a platform of great interest for single-photon generation, quantum sensing, and quantum information science. Photonic crystal cavities (PCCs) can serve as an efficient light–matter interface both to augment the defect emission and to aid in studying the defects’ properties. In this work, we fabricate 1D nanobeam PCCs in 4H-silicon carbide with embedded silicon vacancy centers. These cavities are used to achieve Purcell enhancement of two closely spaced defect zero-phonon lines (ZPL). Enhancements of >80-fold are measured using multiple techniques. Additionally, the nature of the cavity coupling to the different ZPLs is examined.

Silicon carbide has recently been developed as a platform for optically addressable spin defects. In particular, the neutral divacancy in the 4H polytype displays an optically addressable spin-1 ground state and near-infrared optical emission. Here, we present the Purcell enhancement of a single neutral divacancy coupled to a photonic crystal cavity. We utilize a combination of nanolithographic techniques and a dopant-selective photoelectrochemical etch to produce suspended cavities with quality factors exceeding 5,000. Subsequent coupling to a single divacancy leads to a Purcell factor of ~50, which manifests as increased photoluminescence into the zero-phonon line and a shortened excited-state lifetime. Additionally, we measure coherent control of the divacancy ground state spin inside the cavity nanostructure and demonstrate extended coherence through dynamical decoupling. This spin-cavity system represents an advance towards scalable long-distance entanglement protocols using silicon carbide that require the interference of indistinguishable photons from spatially separated single qubits.

The negatively-charged nitrogen vacancy center (NV) in diamond has generated significant interest as a platform for quantum information processing and sensing in the solid state. For most applications, high quality optical cavities are required to enhance the NV zero-phonon line (ZPL) emission. An outstanding challenge in maximizing the degree of NV-cavity coupling is the deterministic placement of NVs within the cavity. Here, we report photonic crystal nanobeam cavities coupled to NVs incorporated by a delta-doping technique that allows nanometer-scale vertical positioning of the emitters. We demonstrate cavities with Q up to ~24,000 and mode volume V ~ 0.47(λ/n) 3 as well as resonant enhancement of the ZPL of an NV ensemble with Purcell factor of ~20. Our fabrication technique provides a first step towards deterministic NV-cavity coupling using spatial control of the emitters.A diamond-based emitter-cavity system provides an important platform for the realization of quantum information processing and sensing in the solid state 1-4 . The long electron spin coherence of the negatively-charged nitrogen vacancy center (subsequently referred to as NV) in

Silicon carbide (SiC) is an intriguing material due to the presence of spin-active point defects in several polytypes, including 4H-SiC. For many quantum information and sensing applications involving such point defects, it is important to couple their emission to high quality optical cavities. Here we present the fabrication of 1D nanobeam photonic crystal cavities (PCC) in 4H-SiC using a dopant-selective etch to undercut a homoepitaxially grown epilayer of p-type 4H-SiC. These are the first PCCs demonstrated in 4H-SiC and show high quality factors (Q) of up to ∼7000 as well as low modal volumes of <0.5 (λ/n)(3). We take advantage of the high device yield of this fabrication method to characterize hundreds of devices and determine which PCC geometries are optimal. Additionally, we demonstrate two methods to tune the resonant wavelengths of the PCCs over 5 nm without significant degradation of the Q. Lastly, we characterize nanobeam PCCs coupled to luminescence from silicon vacancy point defects (V1, V2) in 4H-SiC. The fundamental modes of two such PCCs are tuned into spectral overlap with the zero phonon line (ZPL) of the V2 center, resulting in an intensity increase of up to 3-fold. These results are important steps on the path to developing 4H-SiC as a platform for quantum information and sensing.

The exquisite mechanical properties of SiC have made it an important industrial material with applications in microelectromechanical devices and high power electronics. Recently, the optical properties of SiC have garnered attention for applications in photonics, quantum information, and spintronics. This work demonstrates the fabrication of microdisks formed from a p-N SiC epilayer material. The microdisk cavities fabricated from the SiC epilayer material exhibit quality factors of as high as 9200 and the approach is easily adaptable to the fabrication of SiC-based photonic crystals and other photonic and optomechanical devices. V

High quality, thin diamond membranes containing nitrogen-vacancy centers provide critical advantages in the fabrication of diamond-based structures for a variety of applications, including wide field magnetometry, photonics and bio-sensing. In this work we describe, in detail, the generation of thin, optically-active diamond membranes by means of ion implantation and overgrowth. To establish the suitability of our method for photonic applications, photonic crystal cavities with quality factor of 1000 are fabricated. IntroductionNitrogen-vacancy (NV) centers in diamond have emerged as one of the most promising solid state qubits due to their room temperature operation, long spin coherence times, and suitability for optical initialization and readout [1][2][3][4][5][6]. Beyond their quantum photonic applications, NV centers in diamond have been recently utilized to demonstrate electric and magnetic field sensing with exceptional sensitivity and spatial resolution [7][8][9][10]. Furthermore, the bio-compatibility and the chemical inertness of diamond enable applications of NVs in diamond as biosensors for cellular and neural activities [11][12][13]. Many applications in the field of photonic technologies and bio-sensing require availability of high quality, thin diamond membranes with stable NV centers. For instance, coupling single emitters to photonic crystal cavities (PCCs) or waveguides requires thin (~ 300 nm) diamond membranes having only a few NV centers. [14,15] Alternatively, recent schemes for ensemble magnetometry demand high concentrations of NV centers in a free-standing, single crystal diamond slab [10,16]. Thin diamond membranes with diluted NV centers provide an excellent platform for the formation of optical cavities, strongly coupled to single emitters. Several approaches have been utilized to form free-standing diamond membranes from bulk single-crystal diamond. One approach involves high energy (∼ a few MeV) and high dose ion implantation (∼ 1×10 17 ions/cm 2 ) to selectively damage a portion of the diamond, sub-surface, followed by a lift-off of the membrane [17]. Other approaches employ focused ion beam (FIB) milling to etch or 'cut out' suspended diamond membranes [18,19] and vertical etch of diamond substrates [20]. Unfortunately, in both cases, the process of creating the membrane introduces ion damage that degrades the optical performance of the NVs within the membrane. In addition, a residual built-in strain, resulting from the high ion damage, makes subsequent processing of the membranes extremely challenging [21]. Recently, our group demonstrated that an overgrowth method dramatically improves the optical properties of the membranes, making them suitable for device engineering [22,23]. Subsequent reports have shown that a short overgrowth of diamond

Abstract