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We present the first in-flight results from a novel miniaturised anisotropic magnetoresistive space magnetometer, MAGIC (MAGnetometer from Imperial College), aboard the first CINEMA (CubeSat for Ions, Neutrals, Electrons and MAgnetic fields) spacecraft in low Earth orbit. An attitude-independent calibration technique is detailed using the International Geomagnetic Reference Field (IGRF), which is temperature dependent in the case of the outboard sensor. We show that the sensors accurately measure the expected absolute field to within 2% in attitude mode and 1% in science mode. Using a simple method we are able to estimate the spacecraft's attitude using the magnetometer only, thus characterising CINEMA's spin, precession and nutation. Finally, we show that the outboard sensor is capable of detecting transient physical signals with amplitudes of ~ 20–60 nT. These include field-aligned currents at the auroral oval, qualitatively similar to previous observations, which agree in location with measurements from the DMSP (Defense Meteorological Satellite Program) and POES (Polar-orbiting Operational Environmental Satellites) spacecraft. Thus, we demonstrate and discuss the potential science capabilities of the MAGIC instrument onboard a CubeSat platform.

We have developed an automated analysis scheme for meteor head echo observations by the 46.5 MHz Middle and Upper atmosphere (MU) radar near Shigaraki, Japan (34.85° N, 136.10° E). The analysis procedure computes meteoroid range, velocity and deceleration as functions of time with unprecedented accuracy and precision. This is crucial for estimations of meteoroid mass and orbital parameters as well as investigations of the meteoroid-atmosphere interaction processes. In this paper we present this analysis procedure in detail. The algorithms use a combination of single-pulse-Doppler, time-of-flight and pulse-to-pulse phase correlation measurements to determine the radial velocity to within a few tens of metres per second with 3.12 ms time resolution. Equivalently, the precision improvement is at least a factor of 20 compared to previous single-pulse measurements. Such a precision reveals that the deceleration increases significantly during the intense part of a meteoroid's ablation process in the atmosphere. From each received pulse, the target range is determined to within a few tens of meters, or the order of a few hundredths of the 900 m long range gates. This is achieved by transmitting a 13-bit Barker code oversampled by a factor of two at reception and using a novel range interpolation technique. The meteoroid velocity vector is determined from the estimated radial velocity by carefully taking the location of the meteor target and the angle from its trajectory to the radar beam into account. The latter is determined from target range and bore axis offset. We have identified and solved the signal processing issue giving rise to the peculiar signature in signal to noise ratio plots reported by Galindo et al. (2011), and show how to use the range interpolation technique to differentiate the effect of signal processing from physical processes.

Spintronics: diamonds make sense A type of natural impurity in diamond crystals, called a nitrogen-vacancy centre, has a unique, long-lived single electron spin state that can be controlled and detected optically. This property can be used to create 'spintronics' devices and has possible application in quantum information processing. Two groups this week describe the application of this technology to nanoscale magnetic resonance imaging. Maze et al . demonstrate magnetic sensing using coherent control of diamond spins. They show that in principle, precision measurements of nano-tesla magnetic fields are possible, corresponding roughly to the field of a single proton at a distance of 10 nm. Balasubramanian et al . demonstrate initial steps towards a sensitive, high-resolution imaging technique using diamond spins. They show that the location of single nitrogen-vacancy spins can be determined to 5-nm resolution. In an accompanying News & Views, Michael Romalis observes that a combination of these two techniques could lead to detection and imaging of individual nuclear spins, even the structure determination for a single molecule. And as both experiments were done at room temperature, biological applications of these methods can be anticipated. A naturally occurring impurity in diamond crystals, the nitrogen-vacancy centre, has been found to have a unique, long-lived single electron spin state that can be controlled and detected optically. An approach to magnetic sensing by coherent control of such diamond spins is demonstrated, and it is shown that precision measurements of nanoTesla magnetic fields are in principle possible. Detection of weak magnetic fields with nanoscale spatial resolution is an outstanding problem in the biological and physical sciences 1 , 2 , 3 , 4 , 5 . For example, at a distance of 10 nm, the spin of a single electron produces a magnetic field of about 1 μT, and the corresponding field from a single proton is a few nanoteslas. A sensor able to detect such magnetic fields with nanometre spatial resolution would enable powerful applications, ranging from the detection of magnetic resonance signals from individual electron or nuclear spins in complex biological molecules 5 , 6 to readout of classical or quantum bits of information encoded in an electron or nuclear spin memory 7 . Here we experimentally demonstrate an approach to such nanoscale magnetic sensing, using coherent manipulation of an individual electronic spin qubit associated with a nitrogen-vacancy impurity in diamond at room temperature 8 . Using an ultra-pure diamond sample, we achieve detection of 3 nT magnetic fields at kilohertz frequencies after 100 s of averaging. In addition, we demonstrate a sensitivity of 0.5 μT Hz -1/2 for a diamond nanocrystal with a diameter of 30 nm.

The AWARE-2 camera uses a parallel array of microcameras to capture one-gigapixel images at three frames per minute. Very candid camera Current digital cameras operate around megapixels. Broadly speaking, the higher the pixel count, the more enlargement an image can take. But when gigapixel 'supercameras' become readily available, photography will undergo a second digital revolution. The current emphasis on visual image capture will be a thing of the past. Gigapixel cameras will generate massive data sets, so the emphasis will be on post-capture analysis and data-mining. It is already possible to achieve an arbitrarily large pixel count using massed arrays of cameras, but at a high cost and with extreme complexity. These authors have developed a compact gigapixel camera capable of taking gigapixel images at three frames per minute. The system is based on a 'multiscale' optical system and a specially designed electronic processing unit to process the large volume of imaging information at high speed. They demonstrate with imaging examples that a wealth of information can be obtained from gigapixel snapshots. Pixel count is the ratio of the solid angle within a camera’s field of view to the solid angle covered by a single detector element. Because the size of the smallest resolvable pixel is proportional to aperture diameter and the maximum field of view is scale independent, the diffraction-limited pixel count is proportional to aperture area. At present, digital cameras operate near the fundamental limit of 1–10 megapixels for millimetre-scale apertures, but few approach the corresponding limits of 1–100 gigapixels for centimetre-scale apertures. Barriers to high-pixel-count imaging include scale-dependent geometric aberrations, the cost and complexity of gigapixel sensor arrays, and the computational and communications challenge of gigapixel image management. Here we describe the AWARE-2 camera, which uses a 16-mm entrance aperture to capture snapshot, one-gigapixel images at three frames per minute. AWARE-2 uses a parallel array of microcameras to reduce the problems of gigapixel imaging to those of megapixel imaging, which are more tractable. In cameras of conventional design, lens speed and field of view decrease as lens scale increases 1 , but with the experimental system described here we confirm previous theoretical results 2 , 3 , 4 , 5 , 6 suggesting that lens speed and field of view can be scale independent in microcamera-based imagers resolving up to 50 gigapixels. Ubiquitous gigapixel cameras may transform the central challenge of photography from the question of where to point the camera to that of how to mine the data.

Spintronics: diamonds make sense A type of natural impurity in diamond crystals, called a nitrogen-vacancy centre, has a unique, long-lived single electron spin state that can be controlled and detected optically. This property can be used to create 'spintronics' devices and has possible application in quantum information processing. Two groups this week describe the application of this technology to nanoscale magnetic resonance imaging. Maze et al . demonstrate magnetic sensing using coherent control of diamond spins. They show that in principle, precision measurements of nano-tesla magnetic fields are possible, corresponding roughly to the field of a single proton at a distance of 10 nm. Balasubramanian et al . demonstrate initial steps towards a sensitive, high-resolution imaging technique using diamond spins. They show that the location of single nitrogen-vacancy spins can be determined to 5-nm resolution. In an accompanying News & Views, Michael Romalis observes that a combination of these two techniques could lead to detection and imaging of individual nuclear spins, even the structure determination for a single molecule. And as both experiments were done at room temperature, biological applications of these methods can be anticipated. The nitrogen-vacancy (NV) centre, a naturally occurring impurity in diamond crystals, has a unique, long-lived single-electron spin state that can be controlled and detected optically. This paper demonstrates the first steps towards a sensitive, high-resolution imaging technique in which these diamond spins are exploited. It is shown that the location of single NV spins can be determined with nanometre scale resolution, at ambient conditions, using magneto-optical spin detection. Magnetic resonance imaging and optical microscopy are key technologies in the life sciences. For microbiological studies, especially of the inner workings of single cells, optical microscopy is normally used because it easily achieves resolution close to the optical wavelength. But in conventional microscopy, diffraction limits the resolution to about half the wavelength. Recently, it was shown that this limit can be partly overcome by nonlinear imaging techniques 1 , 2 , but there is still a barrier to reaching the molecular scale. In contrast, in magnetic resonance imaging the spatial resolution is not determined by diffraction; rather, it is limited by magnetic field sensitivity, and so can in principle go well below the optical wavelength. The sensitivity of magnetic resonance imaging has recently been improved enough to image single cells 3 , 4 , and magnetic resonance force microscopy 5 has succeeded in detecting single electrons 6 and small nuclear spin ensembles 7 . However, this technique currently requires cryogenic temperatures, which limit most potential biological applications 8 . Alternatively, single-electron spin states can be detected optically 9 , 10 , even at room temperature in some systems 11 , 12 , 13 , 14 . Here we show how magneto-optical spin detection can be used to determine the location of a spin associated with a single nitrogen-vacancy centre in diamond with nanometre resolution under ambient conditions. By placing these nitrogen-vacancy spins in functionalized diamond nanocrystals, biologically specific magnetofluorescent spin markers can be produced. Significantly, we show that this nanometre-scale resolution can be achieved without any probes located closer than typical cell dimensions. Furthermore, we demonstrate the use of a single diamond spin as a scanning probe magnetometer to map nanoscale magnetic field variations. The potential impact of single-spin imaging at room temperature is far-reaching. It could lead to the capability to probe biologically relevant spins in living cells.

Coherent diffractive imaging (CDI) and scanning transmission x-ray microscopy (STXM) are two popular microscopy techniques that have evolved quite independently. CDI promises to reach resolutions below 10 nanometers, but the reconstruction procedures put stringent requirements on data quality and sample preparation. In contrast, STXM features straightforward data analysis, but its resolution is limited by the spot size on the specimen. We demonstrate a ptychographic imaging method that bridges the gap between CDI and STXM by measuring complete diffraction patterns at each point of a STXM scan. The high penetration power of x-rays in combination with the high spatial resolution will allow investigation of a wide range of complex mesoscopic life and material science specimens, such as embedded semiconductor devices or cellular networks.

We have developed a nanowire nanogenerator that is driven by an ultrasonic wave to produce continuous direct-current output. The nanogenerator was fabricated with vertically aligned zinc oxide nanowire arrays that were placed beneath a zigzag metal electrode with a small gap. The wave drives the electrode up and down to bend and/or vibrate the nanowires. A piezoelectric-semiconducting coupling process converts mechanical energy into electricity. The zigzag electrode acts as an array of parallel integrated metal tips that simultaneously and continuously create, collect, and output electricity from all of the nanowires. The approach presents an adaptable, mobile, and cost-effective technology for harvesting energy from the environment, and it offers a potential solution for powering nanodevices and nanosystems.

Nitrogen-vacancy (NV) color centers in diamond are currently considered excellent solid-state magnetic field sensors. Their long coherence times at room temperature and their atomic size allow for achieving both high magnetic field sensitivity and nanoscale spatial resolution in ambient conditions. This article reviews recent progress in magnetic field imaging with NV centers. We focus on two topics: scanning probe techniques with single NV centers and their application in the imaging of nanoscale magnetic structures, as well as recent development of magnetometers with ensembles of NV centers, which image magnetic fields at micron-length scales with extremely high sensitivities.

X-ray microbeams are an emerging characterization tool with broad implications for science, ranging from materials structure and dynamics, to geophysics and environmental science, to biophysics and protein crystallography. We describe how submicrometer hard x-ray beams with the ability to penetrate tens to hundreds of micrometers into most materials and with the ability to determine local composition, chemistry, and (crystal) structure can characterize buried sample volumes and small samples in their natural or extreme environments. Beams less than 10 nanometers have already been demonstrated, and the practical limit for hard x-ray beam size, the limit to trace-element sensitivity, and the ultimate limitations associated with near-atomic structure determinations are the subject of ongoing research.

A few-femtosecond X-ray streak camera has been realized using a pump–probe scheme that samples the transient response of matter to ionizing soft X-ray radiation in the presence of an intense synchronized terahertz field. Borrowing its concept from attosecond metrology, the femtosecond X-ray streak camera fills the gap between conventional streak cameras with typical resolutions of hundreds of femtoseconds and streaking techniques operating in the sub-femtosecond regime. Its single-shot capability permits the duration and time structure of individual X-ray pulses to be determined. For several classes of experiments in time-resolved spectroscopy, diffraction or imaging envisaged with novel accelerator- and laser-based short-pulse X-ray sources this knowledge is essential, but represents a major challenge to X-ray metrology. Here we report on the single-shot characterization of soft X-ray pulses from the free-electron laser facility FLASH. A streak camera for characterizing the ultrashort X-ray pulses produced by a free-electron laser is reported. The scheme has a single-shot capability, a resolution of a few femtoseconds and is expected to become a useful tool for X-ray metrology, including experiments involving time-resolved spectroscopy and imaging.