Radiation hardness of open Fabry-Pérot microcavities.

High-finesse microcavities offer a platform for compact, high-precision sensing by employing high-reflectivity, low-loss mirrors to create effective optical path lengths that are orders of magnitude larger than the device geometry. Here, we investigate the radiation hardness of Fabry-Pérot microcavities formed from dielectric mirrors deposited on the tips of optical fibers. The microcavities are irradiated under both conventional (∼ 0.

Development of a hydrated electron dosimeter for radiotherapy applications: A proof of concept.

Background: Hydrated electrons, which are short-lived products of radiolysis in water, increase the optical absorption of water, providing a pathway toward near-tissue-equivalent clinical radiation dosimeters. This has been demonstrated in high-dose-per-pulse radiochemistry research, but, owing to the weak absorption signal, its application in existing low-dose-per-pulse radiotherapy provided by clinical linear accelerators (linacs) has yet to be investigated.

Purpose: The aims of this study were to measure the optical absorption associated with hydrated electrons produced by clinical linacs and to assess the suitability of the technique for radiotherapy (⩽ 1 cGy per pulse) applications.

GEANT4-DNA simulation of temperature-dependent and pH-dependent yields of chemical radiolytic species.

GEANT4-DNA can simulate radiation chemical yield (-value) for radiolytic species such as the hydrated electron (eaq-) with the independent reaction times (IRT) method, however, only at room temperature and neutral pH. This work aims to modify the GEANT4-DNA source code to enable the calculation of-values for radiolytic species at different temperatures and pH values.In the GEANT4-DNA source code, values of chemical parameters such as reaction rate constant, diffusion coefficient, Onsager radius, and water density were replaced by corresponding temperature-dependent polynomials.

Effects of incoming particle energy and cluster size on the G-value of hydrated electrons.

In hydrated electron (e) dosimetry, absorbed radiation dose to water is measured by monitoring the concentration of radiation-induced e. However, to obtain accurate dose, the radiation chemical yield of e, G(e), is needed for the radiation quality/setup under investigation. The aim of this study was to investigate the time-evolution of the G-values for the main generated reactive species during water radiolysis using GEANT4-DNA.

Sideband cavity absorption readout (SideCAR) with a robust frequency lock.

We present a simple, continuous, cavity-enhanced optical absorption measurement technique based on high-bandwidth Pound-Drever-Hall (PDH) sideband locking. The technique provides a resonant amplitude quadrature readout that can be mapped onto the cavity's internal loss rate and is naturally compatible with weak probe beams. With a proof-of-concept 5-cm-long Fabry-Perot cavity, we measure an absorption sensitivity ∼10cm/Hz from 30 kHz to 1 MHz, and a minimum value of 6.

Cell-Biomaterial constructs for wound healing and skin regeneration.

Over the years, conventional skin grafts, such as full-thickness, split-thickness, and pre-sterilized grafts from human or animal sources, have been at the forefront of skin wound care. However, these conventional grafts are associated with major challenges, including supply shortage, rejection by the immune system, and disease transmission following transplantation. Due to recent progress in nanotechnology and material sciences, advanced artificial skin grafts-based on the fundamental concepts of tissue engineering-are quickly evolving for wound healing and regeneration applications, mainly because they can be uniquely tailored to meet the requirements of specific injuries.

A Transgenic Rat for Noninvasive Assessment of Chondrogenesis .

Objective: To support the preclinical evaluation of therapeutics that target chondrogenesis, our goal was to generate a rat strain that can noninvasively report endogenous chondrogenic activity.

Design: A transgene was constructed in which the dual expression of bioluminescent (firefly luciferase) and fluorescent (mCherry) reporters is controlled by regulatory sequences from rat Col2a1. Candidate lines were established on a Lewis background and characterized by serial bioluminescence imaging as well as measurement of molecular reporter levels in several tissues.

A mechanically stable and tunable cryogenic Fabry-Pérot microcavity.

High-finesse, open-geometry microcavities have recently emerged as a versatile tool for enhancing interactions between photons and material systems with a range of applications in quantum optics and quantum information science. However, mechanical vibrations pose a considerable challenge to their operation within a closed-cycle cryostat, particularly when spatial tunability and free-space optical access are required. Here, we present the design and characterization of a system that can achieve ∼16 pm-rms passive mechanical stability between two high-finesse mirrors with 34% duty cycle while permitting both three-dimensional positioning of the cavity mode and free-space confocal imaging.

Dendritic cell biocompatibility of ether-based urethane films.

The use of synthetic materials for biomedical applications is ever expanding. One of the major requirements for these materials is biocompatibility, which includes prevention of immune system responses. Due to the inherent complexity of their structural composition, the polyurethane (PU) family of polymers is being used in a variety of medical applications, from soft and hard tissue scaffolds to intricate coatings on implantable devices.

Probing a Spin Transfer Controlled Magnetic Nanowire with a Single Nitrogen-Vacancy Spin in Bulk Diamond.

The point-like nature and exquisite magnetic field sensitivity of the nitrogen vacancy (NV) center in diamond can provide information about the inner workings of magnetic nanocircuits in complement with traditional transport techniques. Here, we use a single NV in bulk diamond to probe the stray field of a ferromagnetic nanowire controlled by spin transfer (ST) torques. We first report an unambiguous measurement of ST tuned, parametrically driven, large-amplitude magnetic oscillations.

High mechanical bandwidth fiber-coupled Fabry-Perot cavity.

Fiber-based optical microcavities exhibit high quality factor and low mode volume resonances that make them attractive for coupling light to individual atoms or other microscopic systems. Moreover, their low mass should lead to excellent mechanical response up to high frequencies, opening the possibility for high bandwidth stabilization of the cavity length. Here, we demonstrate a locking bandwidth of 44 kHz achieved using a simple, compact design that exploits these properties.

Mid-Pleistocene climate transition drives net mass loss from rapidly uplifting St. Elias Mountains, Alaska.

Erosion, sediment production, and routing on a tectonically active continental margin reflect both tectonic and climatic processes; partitioning the relative importance of these processes remains controversial. Gulf of Alaska contains a preserved sedimentary record of the Yakutat Terrane collision with North America. Because tectonic convergence in the coastal St.

Heralded entanglement between solid-state qubits separated by three metres.

Quantum entanglement between spatially separated objects is one of the most intriguing phenomena in physics. The outcomes of independent measurements on entangled objects show correlations that cannot be explained by classical physics. As well as being of fundamental interest, entanglement is a unique resource for quantum information processing and communication.

Review of red yeast rice content and current Food and Drug Administration oversight.

Background: Red yeast rice (RYR) is a commonly used dietary supplement for the management of dyslipidemia. In 2007, the Food and Drug Administration (FDA) issued a consumer warning to avoid RYR products because they may contain unauthorized drug (lovastatin) and also implemented Current Good Manufacturing Practices (CGMP) requiring that proper controls be in place by dietary supplement companies to ensure products are manufactured and processed in a consistent manner and produce high-quality products that are not adulterated with impurities or contaminants and are accurately labeled.

Objective: To assess the FDA oversight of companies manufacturing RYR products and review the labeled content of available RYR products.

Two-photon quantum interference from separate nitrogen vacancy centers in diamond.

We report on the observation of quantum interference of the emission from two separate nitrogen vacancy (NV) centers in diamond. Taking advantage of optically induced spin polarization in combination with polarization filtering, we isolate a single transition within the zero-phonon line of the nonresonantly excited NV centers. The time-resolved two-photon interference contrast of this filtered emission reaches 66%.

High-fidelity projective read-out of a solid-state spin quantum register.

Initialization and read-out of coupled quantum systems are essential ingredients for the implementation of quantum algorithms. Single-shot read-out of the state of a multi-quantum-bit (multi-qubit) register would allow direct investigation of quantum correlations (entanglement), and would give access to further key resources such as quantum error correction and deterministic quantum teleportation. Although spins in solids are attractive candidates for scalable quantum information processing, their single-shot detection has been achieved only for isolated qubits.

Quantum entanglement between an optical photon and a solid-state spin qubit.

Quantum entanglement is among the most fascinating aspects of quantum theory. Entangled optical photons are now widely used for fundamental tests of quantum mechanics and applications such as quantum cryptography. Several recent experiments demonstrated entanglement of optical photons with trapped ions, atoms and atomic ensembles, which are then used to connect remote long-term memory nodes in distributed quantum networks.

Coherence of an optically illuminated single nuclear spin qubit.

We investigate the coherence properties of individual nuclear spin quantum bits in diamond [Dutt, Science 316, 1312 (2007)10.1126/science.1139831] when a proximal electronic spin associated with a nitrogen-vacancy (N-V) center is being interrogated by optical radiation.

Quantum register based on individual electronic and nuclear spin qubits in diamond.

The key challenge in experimental quantum information science is to identify isolated quantum mechanical systems with long coherence times that can be manipulated and coupled together in a scalable fashion. We describe the coherent manipulation of an individual electron spin and nearby individual nuclear spins to create a controllable quantum register. Using optical and microwave radiation to control an electron spin associated with the nitrogen vacancy (NV) color center in diamond, we demonstrated robust initialization of electron and nuclear spin quantum bits (qubits) and transfer of arbitrary quantum states between them at room temperature.

Coherent dynamics of coupled electron and nuclear spin qubits in diamond.

Understanding and controlling the complex environment of solid-state quantum bits is a central challenge in spintronics and quantum information science. Coherent manipulation of an individual electron spin associated with a nitrogen-vacancy center in diamond was used to gain insight into its local environment. We show that this environment is effectively separated into a set of individual proximal 13C nuclear spins, which are coupled coherently to the electron spin, and the remainder of the 13C nuclear spins, which cause the loss of coherence.

Fault-tolerant quantum communication based on solid-state photon emitters.

We describe a novel protocol for a quantum repeater that enables long-distance quantum communication through realistic, lossy photonic channels. Contrary to previous proposals, our protocol incorporates active purification of arbitrary errors at each step of the protocol using only two qubits at each repeater station. Because of these minimal physical requirements, the present protocol can be realized in simple physical systems such as solid-state single photon emitters.

Shaping quantum pulses of light via coherent atomic memory.

We describe proof-of-principle experiments demonstrating a novel approach for generating pulses of light with controllable photon numbers, propagation direction, timing, and pulse shapes. The approach is based on preparation of an atomic ensemble in a state with a desired number of atomic spin excitations, which is later converted into a photon pulse. Spatiotemporal control over the pulses is obtained by exploiting long-lived coherent memory for photon states and Electromagnetically Induced Transparency in an optically dense atomic medium.