Single-spin stochastic optical reconstruction microscopy

We experimentally demonstrate precision addressing of single-quantum emitters by combined optical microscopy and spin resonance techniques. To this end, we use nitrogen vacancy (NV) color centers in diamond confined within a few ten nanometers as individually resolvable quantum systems. By developing a stochastic optical reconstruction microscopy (STORM) technique for NV centers, we are able to simultaneously perform sub–diffraction-limit imaging and optically detected spin resonance (ODMR) measurements on NV spins. This allows the assignment of spin resonance spectra to individual NV center locations with nanometer-scale resolution and thus further improves spatial discrimination. For example, we resolved formerly indistinguishable emitters by their spectra. Furthermore, ODMR spectra contain metrology information allowing for sub–diffraction-limit sensing of, for instance, magnetic or electric fields with inherently parallel data acquisition. As an example, we have detected nuclear spins with nanometer-scale precision. Finally, we give prospects of how this technique can evolve into a fully parallel quantum sensor for nanometer resolution imaging of delocalized quantum correlations.Stochastic reconstruction microscopy (STORM) techniques have led to a wealth of applications in fluorescence imaging (1–3); for example, few ten-nanometers 3D spatial resolution (lateral 20 nm, axial 50 nm) has been achieved in cellular imaging. So far, STORM fluorophores have been used as markers to achieve nanoscale microscopy of specific targets (4). Here, we present a spin-based approach that promises to combine sub–diffraction-limit imaging via STORM and simultaneous sensing of various physical quantities.As a prominent multipurpose probe and highly photostable single emitter, we use the nitrogen vacancy (NV) spin defect in diamond. It can be applied for nanometer-scale scanning magnetometry (5–8) as well as magnetic imaging (9–14) (e.g., for imaging spin distributions, magnetic particles or organisms, or device intrinsic fields), the measurement of electric fields, and diamond lattice strain (15–18) (e.g., for imaging elementary charges or charge distributions, or for imaging strain fields induced by mechanical action on the diamond surface). Very recently, precise temperature measurements (19, 20) even in living cells (21) have been demonstrated.During the last decades, a variety of methods have been invented to circumvent the diffraction limit in farfield optical microscopy. One approach reduces the spatial region within a laser focus from which optical response of a single emitter is possible by exploiting optical nonlinearities. Examples are stimulated emission depletion (STED) and ground-state depletion (GSD) microscopy (22, 23). Another approach tailors the timing of optical response of several emitters from within a diffraction-limited spot to distinguish them in the time domain. One example is stochastic optical reconstruction microscopy (24–26). This latter technique is intrinsically parallel as it uses a CCD array for imaging and is therefore particularly suited for high-throughput imaging.STED and GSD microscopy, which are both scanning techniques, have been recently implemented for NV centers in diamond (27, 28) with resolutions down to a few nanometers (29). In addition, localization-based superresolution microscopy has been shown with NV centers in nanodiamonds (30).Here, we experimentally demonstrate STORM for NV centers in diamond as a new optical superresolution technique with wide-field parallel image acquisition for NV centers in bulk diamond. Our technique is based on recently gained profound knowledge about statistical charge state switching of single NV centers (31), and its scalability relies on the homogeneity of this charge state dynamics for NV centers in bulk diamond. Furthermore, we combine optical superresolution microscopy with high–spectral-resolution optically detected magnetic resonance (ODMR). On the one hand, we use the latter technique to assign magnetic resonance data to nanometer-scale locations, which is important for qubit or metrology applications (9–11, 32). On the other hand, different magnetic resonance fingerprints of closely spaced NV centers are used to further increase the already obtained superresolution, as demonstrated in refs. 32 and 33, which is important for emitter localization in imaging applications.