This work presents stochastic approaches to model the counting behavior of actively quenched single-photon avalanche diodes (SPADs) subjected to continuous-wave constant illumination. We present both analytical expressions and simulation algorithms predicting the distribution of the number of detections in a finite time window. We also present formulas for the mean detection rate. The approaches cover recovery time, afterpulsing, and twilight pulsing. We experimentally compare the theoretical predictions to measured data using commercially available silicon SPADs. Their total variation distances range from 10 −5 to 10 −2 .
Eyelid margin tumors require special attention based on both anatomical and histological perspectives. Our aim in this study was to evaluate carbon dioxide (CO) laser therapy for the treatment of eyelid margin tumors. Fifty-two patients with 55 eyelid margin tumors were included in this study. All tumors were removed with a CO laser, and histopathological evaluation was obtained in 52 cases. All patients were followed up for a mean period of 8.5 months (range 6 to 14 months). There were no bleedings in the intra- and postoperative period; the wounds were dry and reepithelized after 10-14 days and no recurrence occurred during follow-up period. Compared to the surrounding tissue, the treated area was hypopigmented and maximum five eyelashes (average 2.5) were wasted during the procedure. We achieved complete patient and surgeon satisfaction with cosmetic and therapeutic results. CO laser treatment of eyelid margin is a safe and effective procedure; its cosmetic result is beneficial as it does not cause malposition of the eyelid or damage to the lacrimal drainage system if the tumor is located in its proximity.
We report on direct experimental certification of the quantum non-Gaussian character of a photon number-resolving detector. The certification protocol is based on an adaptation of the existing quantum non-Gaussianity criteria for quantum states to quantum measurements. In our approach, it suffices to probe the detector with a vacuum state and two different thermal states to test its quantum non-Gaussianity. The certification is experimentally demonstrated for the detector formed by a spatially multiplexed array of ten single-photon avalanche photodiodes. We confirm the quantum non-Gaussianity of POVM elements
Π
^
m
associated with the m-fold coincidence counts, up to m = 7. The experimental ability to certify from the first principles the quantum non-Gaussian character of
Π
^
m
is for large m limited by low probability of the measurement outcomes, especially for vacuum input state. We find that the injection of independent Gaussian background noise into the detector can be helpful and may reduce the measurement time required for reliable confirmation of quantum non-Gaussianity. In addition, we modified and experimentally verified the quantum non-Gaussianity certification protocol employing a third thermal state instead of a vacuum to speed up the whole measurement. Our findings demonstrate the existence of efficient tools for the practical characterization of fundamental non-classical properties and benchmarking of complex optical quantum detectors.
We present advanced methods of photon-number-resolving detection, which allow for photon statistics measurement and quantum feature extraction with unprecedented accuracy and dynamic range. Applications include nonclassicality and non-Gaussianity detection, photon statistics discrimination, and conditional preparation.
We have devised and experimentally demonstrated a direct certification of the strong non-classical character of quantum measurement devices, namely single-photon avalanche diodes and photon-number-resolving detectors.
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