Super-resolved reconstruction of single-photon emitter locations from $g^{(2)}(0)$ mapsSuper-resolved reconstruction of single-photon emitter locations from $g^{(2)}(0)$ maps

Sonali Gupta, Amit Kumar, Vikas S Bhat +1 more

Single-photon sources are vital for emerging quantum technologies. In particular, Nitrogen-vacancy (NV) centers in diamond are promising due to their room-temperature stability, long spin coherence, and compatibility with nanophotonic structures. A key challenge, however, is the reliable identification of isolated NV centers, since conventional confocal microscopy is diffraction-limited and cannot resolve emitter distributions within a focal spot. Besides, the associated intensity scanning is a time-expensive procedure. Here, we introduce a raster-scanned $g^{(2)}(0)$ mapping technique combined with an inversion-based reconstruction algorithm. By directly measuring local photon antibunching across the field of view, we extract the effective emitter number within each focal spot and reconstruct occupancy maps on a sub-focal-spot grid. This enables recovery of the number and spatial distribution of emitters within regions smaller than the confocal focal spot, thereby offering possibilities of going beyond the diffraction limit. Our simulations confirm robust reconstruction of NV-center distributions. The method provides a practical diagnostic tool for locating single-photon sources in an efficient and accurate manner, at much lesser time and effort compared to conventional intensity scanning. It offers valuable feedback for nanophotonic device fabrication, supporting more precise and scalable integration of NV-based quantum photonic technologies.Single-photon sources are vital for emerging quantum technologies. In particular, Nitrogen-vacancy (NV) centers in diamond are promising due to their room-temperature stability, long spin coherence, and compatibility with nanophotonic structures. A key challenge, however, is the reliable identification of isolated NV centers, since conventional confocal microscopy is diffraction-limited and cannot resolve emitter distributions within a focal spot. Besides, the associated intensity scanning is a time-expensive procedure. Here, we introduce a raster-scanned $g^{(2)}(0)$ mapping technique combined with an inversion-based reconstruction algorithm. By directly measuring local photon antibunching across the field of view, we extract the effective emitter number within each focal spot and reconstruct occupancy maps on a sub-focal-spot grid. This enables recovery of the number and spatial distribution of emitters within regions smaller than the confocal focal spot, thereby offering possibilities of going beyond the diffraction limit. Our simulations confirm robust reconstruction of NV-center distributions. The method provides a practical diagnostic tool for locating single-photon sources in an efficient and accurate manner, at much lesser time and effort compared to conventional intensity scanning. It offers valuable feedback for nanophotonic device fabrication, supporting more precise and scalable integration of NV-based quantum photonic technologies.

quant-pharXiv:2511.01279Nov 4, 20250 citations

Efficient imaging of quantum emitters using compressive sensing

Sonali Gupta, Kiran Bajar, Alexander McFarland +3 more

Optical imaging of quantum emitters is essential for a wide range of quantum applications. Conventional confocal imaging relies on point-by-point raster scanning, which is inherently time-consuming and photon-inefficient, particularly for sparse emitter distributions and photon-limited samples. Here, we demonstrate a compressive sensing-based imaging approach, where spatially structured wide-field excitation replaces raster scanning, enabling reconstruction of sparse emitters. In our implementation, random binary patterns are used to acquire compressive measurements, from which the spatial fluorescence distribution is reconstructed using a GPSR-BB algorithm. We experimentally demonstrate this approach using nitrogen-vacancy (NV) centers in diamond as a representative platform, with high-fidelity image reconstruction achieved using only approximately $20\%$ of the measurements required for conventional raster scanning. In addition to intensity reconstruction, we extend this framework to reconstruct spatial maps of the second-order correlation function $g^{(2)}(0)$ from compressive measurements. This enables identification of single-photon emitters through antibunching signatures using significantly reduced data.Optical imaging of quantum emitters is essential for a wide range of quantum applications. Conventional confocal imaging relies on point-by-point raster scanning, which is inherently time-consuming and photon-inefficient, particularly for sparse emitter distributions and photon-limited samples. Here, we demonstrate a compressive sensing-based imaging approach, where spatially structured wide-field excitation replaces raster scanning, enabling reconstruction of sparse emitters. In our implementation, random binary patterns are used to acquire compressive measurements, from which the spatial fluorescence distribution is reconstructed using a GPSR-BB algorithm. We experimentally demonstrate this approach using nitrogen-vacancy (NV) centers in diamond as a representative platform, with high-fidelity image reconstruction achieved using only approximately $20\%$ of the measurements required for conventional raster scanning. In addition to intensity reconstruction, we extend this framework to reconstruct spatial maps of the second-order correlation function $g^{(2)}(0)$ from compressive measurements. This enables identification of single-photon emitters through antibunching signatures using significantly reduced data.

physics.opticsCross-listedarXiv:2604.10463Apr 14, 2026

Reconstruction algorithm for g 2 (0) correlation maps using compressively sensed imaging in single-photon emitters

Sonali Gupta, Kiran Bajar, Alexander McFarland +3 more

Optical imaging of quantum emitters is essential for a wide range of quantum applications. Conventional confocal imaging relies on point-by-point raster scanning, which is inherently time-consuming, particularly for sparse emitter distributions and photon-limited samples. Here, we demonstrate a compressive-sensing-based fluorescence imaging approach in which spatially structured wide-field excitation is used to acquire multiplexed measurements of sparse emitters. In our implementation, random binary patterns are projected onto the sample, and the spatial fluorescence distribution is reconstructed from the measured signals using a gradient projection for a sparse reconstruction algorithm with Barzilai Borwein step size (GPSR-BB). We experimentally demonstrate this approach using nitrogen-vacancy (NV) centers in diamond as a representative platform, achieving high-fidelity image reconstruction using only approximately 20% of the measurements required for conventional raster scanning. Beyond intensity reconstruction, we develop a compressive correlation-reconstruction model for recovering spatial maps of the second-order correlation function g (2) (0) from photon-correlation measurements. Through numerical simulations, we show that the reconstructed g (2) (0) maps can identify single-photon-emitter locations using the antibunching criterion g (2) (0) < 0.5. These results demonstrate that compressive sampling can reduce measurement overhead while preserving spatial information and enabling correlation-based quantum-emitter identification.Optical imaging of quantum emitters is essential for a wide range of quantum applications. Conventional confocal imaging relies on point-by-point raster scanning, which is inherently time-consuming, particularly for sparse emitter distributions and photon-limited samples. Here, we demonstrate a compressive-sensing-based fluorescence imaging approach in which spatially structured wide-field excitation is used to acquire multiplexed measurements of sparse emitters. In our implementation, random binary patterns are projected onto the sample, and the spatial fluorescence distribution is reconstructed from the measured signals using a gradient projection for a sparse reconstruction algorithm with Barzilai Borwein step size (GPSR-BB). We experimentally demonstrate this approach using nitrogen-vacancy (NV) centers in diamond as a representative platform, achieving high-fidelity image reconstruction using only approximately 20% of the measurements required for conventional raster scanning. Beyond intensity reconstruction, we develop a compressive correlation-reconstruction model for recovering spatial maps of the second-order correlation function g (2) (0) from photon-correlation measurements. Through numerical simulations, we show that the reconstructed g (2) (0) maps can identify single-photon-emitter locations using the antibunching criterion g (2) (0) < 0.5. These results demonstrate that compressive sampling can reduce measurement overhead while preserving spatial information and enabling correlation-based quantum-emitter identification.

Optics ContinuumAug 3, 20260 citations

Statistical imaging of NV centers reveals clustered defect formation in diamond

Shao, Jason, Richard Monge, Tom Delord +1 more

The sharp optical resonances of NV- centers in diamond at cryogenic temperatures offer powerful new capabilities for material characterization, but extracting the most detailed information typically requires careful calibration of individual sensors, limiting scalability. In this work, we use resonant photoluminescence excitation imaging to optically resolve and monitor hundreds of individual NVs across large fields of view, enabling statistical analysis of their spatial distribution with sub-diffraction resolution. This multiplexed, non-destructive approach allows quantum sensors to characterize the material platform they inhabit. Focusing on CVD-grown diamond, we uncover significant deviations from random distributions, including an unexpectedly high occurrence of closely spaced clusters comprising two or more NVs. These findings suggest non-Poissonian formation dynamics and point to spatially correlated defect generation mechanisms. Beyond offering insight into diamond growth and NV center formation, our approach enables the scalable identification of naturally occurring NV clusters - configurations that are promising for entanglement-assisted quantum information protocols and correlated sensing - and establishes a path toward structural and electronic defect analysis in various material hosts at the single-emitter level.The sharp optical resonances of NV- centers in diamond at cryogenic temperatures offer powerful new capabilities for material characterization, but extracting the most detailed information typically requires careful calibration of individual sensors, limiting scalability. In this work, we use resonant photoluminescence excitation imaging to optically resolve and monitor hundreds of individual NVs across large fields of view, enabling statistical analysis of their spatial distribution with sub-diffraction resolution. This multiplexed, non-destructive approach allows quantum sensors to characterize the material platform they inhabit. Focusing on CVD-grown diamond, we uncover significant deviations from random distributions, including an unexpectedly high occurrence of closely spaced clusters comprising two or more NVs. These findings suggest non-Poissonian formation dynamics and point to spatially correlated defect generation mechanisms. Beyond offering insight into diamond growth and NV center formation, our approach enables the scalable identification of naturally occurring NV clusters - configurations that are promising for entanglement-assisted quantum information protocols and correlated sensing - and establishes a path toward structural and electronic defect analysis in various material hosts at the single-emitter level.

arXiv:2511.03411Nov 5, 20250 citations

Quantum efficiency of single NV centers in nanodiamonds

Abbas Mohtashami, Martin Frimmer, A. Femius Koenderink

Nitrogen-vacancy (NV) centers in nanodiamond are photostable single photon emitters at room temperature and are considered to be promising candidates for integrated nanophotonics and quantum information processing. A successful implementation of NV centers in nanophotonic devices requires knowledge about the photophysical properties of each emitter such as brightness, decay rate and quantum efficiency. Recent reports show that not all NV centers in diamond nanocrystals are identical and indeed show distributions in brightness and decay rate [1,2]. Here, we report on experimental quantification of the quantum efficiency (QE) of individual nanodiamonds containing single NV centers. Additionally, we report on measurements of decay rate and brightness of single nanodiamond NV centers and discuss if/which NV centers are suitable emitters to be integrated in nanophotonic devices.Nitrogen-vacancy (NV) centers in nanodiamond are photostable single photon emitters at room temperature and are considered to be promising candidates for integrated nanophotonics and quantum information processing. A successful implementation of NV centers in nanophotonic devices requires knowledge about the photophysical properties of each emitter such as brightness, decay rate and quantum efficiency. Recent reports show that not all NV centers in diamond nanocrystals are identical and indeed show distributions in brightness and decay rate [1,2]. Here, we report on experimental quantification of the quantum efficiency (QE) of individual nanodiamonds containing single NV centers. Additionally, we report on measurements of decay rate and brightness of single nanodiamond NV centers and discuss if/which NV centers are suitable emitters to be integrated in nanophotonic devices.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)May 1, 20133 citations

Single-spin stochastic optical reconstruction microscopy

Matthias Pfender, Nabeel Aslam, G. Waldherr +2 more

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.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.

arXiv:1404.1520Proceedings of the National Academy of SciencesSep 29, 201491 citations

Super-resolved reconstruction of single-photon emitter locations from

g^{(2)}(0)

maps

g^{(2)}(0)

mapping technique combined with an inversion-based reconstruction algorithm. By directly measuring local photon antibunching across the field of view, we extract the effective emitter number within each focal spot and reconstruct occupancy maps on a sub-focal-spot grid. This enables recovery of the number and spatial distribution of emitters within regions smaller than the confocal focal spot, thereby offering possibilities of going beyond the diffraction limit. Our simulations confirm robust reconstruction of NV-center distributions. The method provides a practical diagnostic tool for locating single-photon sources in an efficient and accurate manner, at much lesser time and effort compared to conventional intensity scanning. It offers valuable feedback for nanophotonic device fabrication, supporting more precise and scalable integration of NV-based quantum photonic technologies.

20\%

of the measurements required for conventional raster scanning. In addition to intensity reconstruction, we extend this framework to reconstruct spatial maps of the second-order correlation function

g^{(2)}(0)

from compressive measurements. This enables identification of single-photon emitters through antibunching signatures using significantly reduced data.