Abstract: A sensor assembly comprising single crystal diamond material, the single crystal diamond material comprising a surface which is configured in use to contact a fluid, the surface comprising a sensing surface region, wherein the single crystal diamond material comprises a plurality of quantum spin defects in proximity to the sensing surface region. The sensor assembly further comprises a first electrode and a second electrode. The electrodes are located such that, in use, they generate an electric field proximate to a surface of the sensing surface region, the electric field being sufficient to generate oxidising species in the fluid for removing contaminant material from the sensing surface region.

Abstract: A sensor device formed of diamond material. The sensor device has a spin defect located in the diamond material, and an electrically conducting region located so as to be interactable with the spin defect. The electrically conducting region extends from an interior location of the diamond material to a surface of the diamond material. The electrically conducting region at the surface of the diamond material is arranged to connect to a detector, the detector configured to detect charge carriers excited from the at least one spin defect via the electrically conducting region. This allows the use of a higher volume of the diamond sensor than would be the case if one were limited to using spin defects close to the surface.

Abstract: A device that utilises an electronic Zeeman splitting effect comprises a solid-state material that comprises at least one spin defect. The device also comprises a magnetic field generator configured to generate a bias magnetic field, and a compensation system to compensate for an effect of changes in temperature on the bias magnetic field. The compensation comprises a temperature sensor configured to measure any of a temperature and a change in temperature of the magnetic-field generator, and a computer device configured to determine a change in the bias magnetic field as a result of a change in the measured temperature or the measured change in temperature. The computer device is further configured to adjust a predetermined bias magnetic field value using the determined change in bias magnetic field and using the value as an input to the compensation system to compensate for the effect of changes in temperature on the bias magnetic field.

Abstract: Single crystal CVD diamond material comprising a total nitrogen concentration of at least 5 ppm and a neutral single substitutional nitrogen. Ns0, to total single substitutional nitrogen, Ns, ratio of at least 0.7. Such a diamond is observed to have a relatively low amount of brown colouration despite the relatively high concentration of nitrogen A method of making the single crystal diamond is also disclosed, the method including growing the CVD diamond in process gases comprising 60 to 200 ppm nitrogen, in addition to a carbon-containing gas, and hydrogen, wherein the ratio of carbon atoms in the carbon-containing gas to hydrogen atoms in the hydrogen gas is 0.5 to 1.5%.

Abstract: A method of forming a diamond composite body and the diamond composite body. A first single crystal diamond body is provided, which contains nitrogen and has a uniform strain such that over an area of at least 1×1 mm, at least 90 percent of points display a modulus of strain-induced shift of NV resonance of less than 200 kHz, wherein each point in the area is a resolved region of 50 ?m2. The first single crystal diamond body is treated to convert at least some of the nitrogen to form at least 0.3 ppm nitrogen-vacancy, NV?, centres. A CVD process is used to grow a second single crystal diamond body on a surface of the first single crystal diamond body. The second single crystal diamond body has an NV concentration less than or equal to 10 times lower than the NV? concentration in the first single crystal diamond body.

Abstract: A single crystal CVD diamond material is disclosed, the material comprising a total nitrogen concentration of at least 3 ppm as measured by secondary ion mass spectrometry (SIMS); and a low optical birefringence such that in a sample of the single crystal CVD diamond material having an area of at least 1.3 mm×1.3 mm, and measured using a pixel size of area in a range 1×1 ?m2 to 20×20 ?m2, a maximum value of ?n[average] does not exceed 1.5×10?4, where ?n[average] is an average value of a difference between refractive index for light polarised parallel to slow and fast axes averaged over the sample thickness. A method of making the material is also disclosed.

Abstract: A single crystal diamond material comprising: neutral nitrogen-vacancy defects (NV0); negatively charged nitrogen-vacancy defects (NV?); and single substitutional nitrogen defects (Ns) which transfer their charge to the neutral nitrogen-vacancy defects (NV0) to convert them into the negatively charged nitrogen-vacancy defects (NV), characterized in that the single crystal diamond material has a magnetometry figure of merit (FOM) of at least 2, wherein the magnetometry figure of merit is defined by (I) where R is a ratio of concentrations of negatively charged nitrogen-vacancy defects to neutral nitrogen-vacancy defects ([NV?]/[NV0]), [NV?] is the concentration of negatively charged nitrogen-vacancy defects measured in parts-per-million (ppm) atoms of the single crystal diamond material, [NV0] is a concentration of neutral nitrogen-vacancy defects measured in parts-per-million (ppm) atoms of the single crystal diamond material, and T2? is a decoherence time of the NV? defects, where T2? is T2* for DC magnetome

Abstract: A synthetic diamond material comprises a surface, wherein the surface comprises a first surface region comprising a first concentration of quantum spin defects. A second surface region has a predetermined area and is located adjacent to the first surface region, the second region comprising a second concentration of quantum spin defects. The first concentration of quantum spin defects is at least ten times greater than the second concentration of quantum spin defects, and at least one of the first or second surface regions comprises chemical vapour deposition, CVD, synthetic diamond. A method of producing the synthetic diamond material is also disclosed.

Abstract: Disclosed are synthetic diamond materials for quantum and optical applications, such as quantum information processing, quantum key distribution, quantum repeaters, and quantum sensing devices, based on spin defects in diamond. This includes methods for synthesizing and treating diamond in order to create spin defects with improved spin coherence and optical emission properties, as well as treating the diamond to eliminate unwanted defects that degrade these properties.