Devices for determining a state of a magnetic field-generating article are provided. In various embodiments, a device comprises: a single crystal diamond having a plurality of NV centers, the single crystal diamond configured to be disposed adjacent to a magnetic field-generating article, and configured to generate a fluorescent signal in response to being illuminated by a light source; a coherent light source configured to generate a light beam directed at the single crystal diamond; a microwave (MW) radiation source configured to irradiate the single crystal diamond with a MW signal; a magnetic field source configured to apply a bias magnetic field to the single crystal diamond; a photosensor configured to collect the fluorescent signal generated by the single crystal diamond; and a computing node operatively coupled to each of the coherent light source, the MW radiation source, the magnetic field source, and the photosensor.

The present application discloses methods and apparatus for detecting a complex including an analyte that include contacting a sample in a solution with a population of functionalized beads of a first type, which are magnetic functionalized beads and are functionalized to include a first moiety that associates with an analyte under suitable conditions, contacting the sample solution with a population of functionalized beads of a second type, which are functionalized to include a second moiety that associates with the analyte under suitable conditions, contact resulting in formation of a complex including one of the first type of functionalized bead, the analyte, and one of the second type of functionalized bead, and detecting the complex including the analyte by detecting magnetic fields produced by the magnetic functionalized bead and by detecting the functionalized bead of the second type associated with the analyte in the complex.

The present application discloses methods and apparatus for detecting a complex including an analyte that include contacting a sample in a solution with a population of functionalized beads of a first type, which are magnetic functionalized beads and are functionalized to include a first moiety that associates with an analyte under suitable conditions, contacting the sample solution with a population of functionalized beads of a second type, which are functionalized to include a second moiety that associates with the analyte under suitable conditions, contact resulting in formation of a complex including one of the first type of functionalized bead, the analyte, and one of the second type of functionalized bead, and detecting the complex including the analyte by detecting magnetic fields produced by the magnetic functionalized bead and by detecting the functionalized bead of the second type associated with the analyte in the complex.

Provided is a fibrous carbon nanostructure that has excellent dispersibility after surface modification treatment. The fibrous carbon nanostructure has an amount of localized electrons of 1.0×10.sup.17/g or more as determined by electron spin resonance measurement at a temperature of 10 K.

The present disclosure relates to a pH-sensor for determining and/or monitoring a pH value of a medium, having a sensor unit with a wall in contact with the medium, and at least one pH-sensitive material, which has at least one spin state that changes as a function of a pH value. The at least one pH-sensitive material is arranged in or on a region of the wall in such a way that the at least one spin state is subjected to a change in the pH value of the medium. The pH-sensor also includes a spin-sensitive unit, which is configured to detect a variable associated with the at least one spin state, wherein the spin-sensitive unit is arranged in an environment of the at least one pH-sensitive material such that the spin-sensitive unit is subjected to a change in the spin state of the at least one pH-sensitive material.

Embodiments described herein provide systems and methods for acoustically driving spin rotations of diamond nitrogen-vacancy (NV) centers using acoustic transducers. The acoustic transducers may comprise devices such as bulk acoustic resonators or surface acoustic resonators. The systems and methods may allow driving of m.sub.s=0 to m.sub.s=−1, m.sub.s=0 to m.sub.s=+1, m.sub.s=−1 to m.sub.s=0, and m.sub.s=+1 to m.sub.s=0 single-quantum (SQ) spin transitions without the need to apply magnetic field pulses. This may substantially reduce the size and power requirements of NV center-based sensors. The systems and methods may be used to conduct a variety of measurements, such as measurements of magnetic field, electric field, orientation, strain, or temperature.

Embodiments described herein provide systems and methods for acoustically driving spin rotations of diamond nitrogen-vacancy (NV) centers using acoustic transducers. The acoustic transducers may comprise devices such as bulk acoustic resonators or surface acoustic resonators. The systems and methods may allow driving of m.sub.s=0 to m.sub.s=−1, m.sub.s=0 to m.sub.s=+1, m.sub.s=−1 to m.sub.s=0, and m.sub.s=+1 to m.sub.s=0 single-quantum (SQ) spin transitions without the need to apply magnetic field pulses. This may substantially reduce the size and power requirements of NV center-based sensors. The systems and methods may be used to conduct a variety of measurements, such as measurements of magnetic field, electric field, orientation, strain, or temperature.

It is an object of the invention to improve processes, apparatuses and systems for measuring a measured variable. To this end, a measured variable is measured in a measuring process on the basis of an NV center as a quantum sensor. The NV center has a plurality of quantum states and is optically excitable on the basis of an occupancy of one of the quantum states into at least one excited state of the quantum states by means of an excitation light. The at least one excited state can decay at least with emission of emission light of the NV center. In the measuring process, the NV center is irradiated by the excitation light, the excitation light having a time periodic modulation, and a respective occupancy probability and/or a respective lifetime of the quantum states depending on the measured variable and the excitation light. A phase shift is determined between the emission light of the NV center and the modulation of the excitation light and a measurement value for the measured variable is determined on the basis thereof.

It is an object of the invention to improve processes, apparatuses and systems for measuring a measured variable. To this end, a measured variable is measured in a measuring process on the basis of an NV center as a quantum sensor. The NV center has a plurality of quantum states and is optically excitable on the basis of an occupancy of one of the quantum states into at least one excited state of the quantum states by means of an excitation light. The at least one excited state can decay at least with emission of emission light of the NV center. In the measuring process, the NV center is irradiated by the excitation light, the excitation light having a time periodic modulation, and a respective occupancy probability and/or a respective lifetime of the quantum states depending on the measured variable and the excitation light. A phase shift is determined between the emission light of the NV center and the modulation of the excitation light and a measurement value for the measured variable is determined on the basis thereof.

An object provide a technique capable of measuring temperature on the basis of optically detected magnetic resonance with higher precision, The object is achieved by a method for measuring the temperature of an object on the basis of optically detected magnetic resonance of an inorganic fluorescent particle, including (a) irradiating the object, containing the inorganic fluorescent particle with each of multiple microwaves having different frequencies, (b) measuring the fluorescence intensities of the inorganic fluorescent particle with individual photon counters at the time of irradiation of respective microwaves, (c) correcting the fluorescence intensities on the basis of dependencies in the number of pulse measurements between the photon counters and (d) Calculating the temperature of the object on the basis of the obtained fluorescence intensity with the correction values.