Experimental Generation of Spin-Photon Entanglement in Silicon Carbide.

A solid-state approach for quantum networks is advantageous, as it allows the integration of nanophotonics to enhance the photon emission and the utilization of weakly coupled nuclear spins for long-lived storage. Silicon carbide, specifically point defects within it, shows great promise in this regard due to the easy of availability and well-established nanofabrication techniques. Despite of remarkable progresses made, achieving spin-photon entanglement remains a crucial aspect to be realized. In this Letter, we experimentally generate entanglement between a silicon vacancy defect in silicon carbide and a scattered single photon in the zero-phonon line. The spin state is measured by detecting photons scattered in the phonon sideband. The photonic qubit is encoded in the time-bin degree of freedom and measured using an unbalanced Mach-Zehnder interferometer. Photonic correlations not only reveal the quality of the entanglement but also verify the deterministic nature of the entanglement creation process. By harnessing two pairs of such spin-photon entanglement, it becomes straightforward to entangle remote quantum nodes at long distance.

Retrieving profile of photoresist with high aspect ratio and subwavelength features using optical spectroscopy and artificial neural network.

Profile measurements of structures with a high aspect ratio and subwavelength features (HARSW) can be achieved using transmission electron microscopy and tilted scanning electron microscopy. Although electron microscopy can provide accurate HARSW measurements, it is laborious and destructive. In this paper, nondestructive and labor-saving methods were proposed to measure the dimensions of HARSW structures. The optical reflection spectrum, along with an artificial neural network (ANN) model, was adopted for interpolation with the simulation database to retrieve the dimensions of HARSW structures. To generate the ANN model, the experimental and simulated reflection spectra were adopted as the input and output variables for the training data, respectively. This ANN model can learn the discrepancy between simulation and experimental reflections. The finite-difference time-domain method was also adopted to calculate the simulated reflection spectra of HARSW structures with various dimensions, which can be used as a database. Once the experimental reflection of a HARSW structure with unknown dimensions was obtained, the ANN model could generate a simulation-like reflection spectrum. Linear regression was used to determine the correlation coefficients of the simulation-like reflection spectra in the database. The accurate dimensions of HARSW structures can be determined using a higher correlation coefficient. This methodology can be a prominent method for the process monitoring of HARSW structures.

Effective suppression of myocardial glucose uptake using predesigned low-carbohydrate boxed meals.

BACKGROUND: Dietary preparation protocols are an effective means to suppress physiological myocardial 18F-fluorodeoxyglucose (FDG) uptake. This study aimed to investigate the efficacy of various carbohydrate-restricted diets using predesigned boxed meals. METHODS: The patients were divided into four groups to undergo different preparatory protocols as follows: a minimum 15-hour fast alone, two meals of high-fat, low-carbohydrate diet (HFLCD), two meals of high-animal-protein, low-carbohydrate diet (HAPLCD), and two meals of high-plant-based-protein, low-carbohydrate diet (HPPLCD). Boxed meals were prepared to meet the required carbohydrate restrictions. Myocardial SUVmax and SUVmean were measured and the suppression rate was analyzed. RESULTS: The average myocardial SUVmax of fast alone, HFLCD, HAPLCD, and HPPLCD were 8.26 ± 5.85, 2.21 ± 1.50, 2.34 ± 1.88, and 4.10 ± 3.61, respectively, and the suppression rates were 36.6%, 93.3%, 93.3%, and 70%, respectively. The effectiveness of HFLCD, HAPLCD, and HPPLCD was all statistically superior to that of a 15-hour fast alone. SUVmax of HFLCD and HAPLCD showed no significant differences (p = 1), whereas HFLCD and HPPLCD had significant differences (p = .046). CONCLUSIONS: Using the predesigned boxed meals based on carbohydrate restriction, HFLCD, HAPLCD, and HPPLCD can be administered to patients with different dietary needs while providing a substantial reduction in physiological myocardial FDG uptake.

Deterministic Time-Bin Entanglement between a Single Photon and an Atomic Ensemble.

Hybrid matter-photon entanglement is the building block for quantum networks. It is very favorable if the entanglement can be prepared with a high probability. In this Letter, we report the deterministic creation of entanglement between an atomic ensemble and a single photon by harnessing the Rydberg blockade. We design a scheme that creates entanglement between a single photon's temporal modes and the Rydberg levels that host a collective excitation, using a process of cyclical retrieving and patching. The hybrid entanglement is tested via retrieving the atomic excitation as a second photon and performing correlation measurements, which suggest an entanglement fidelity of 87.8%. Our source of matter-photon entanglement will enable the entangling of remote quantum memories with much higher efficiency.

Entanglement of two quantum memories via fibres over dozens of kilometres.

A quantum internet that connects remote quantum processors1,2 should enable a number of revolutionary applications such as distributed quantum computing. Its realization will rely on entanglement of remote quantum memories over long distances. Despite enormous progress3-12, at present the maximal physical separation achieved between two nodes is 1.3 kilometres10, and challenges for longer distances remain. Here we demonstrate entanglement of two atomic ensembles in one laboratory via photon transmission through city-scale optical fibres. The atomic ensembles function as quantum memories that store quantum states. We use cavity enhancement to efficiently create atom-photon entanglement13-15 and we use quantum frequency conversion16 to shift the atomic wavelength to telecommunications wavelengths. We realize entanglement over 22 kilometres of field-deployed fibres via two-photon interference17,18 and entanglement over 50 kilometres of coiled fibres via single-photon interference19. Our experiment could be extended to nodes physically separated by similar distances, which would thus form a functional segment of the atomic quantum network, paving the way towards establishing atomic entanglement over many nodes and over much longer distances.

Semideterministic Entanglement between a Single Photon and an Atomic Ensemble.

Entanglement between a single photon and a matter qubit is an indispensable resource for quantum repeater and quantum networks. With atomic ensembles, the entanglement creation probability is typically very low to inhibit high-order events. In this paper, we propose and experimentally realize a scheme that creates atom-photon entanglement with an intrinsic efficiency of 50%. We make use of Rydberg blockade to generate two collective excitations, lying in separate internal states. By introducing the momentum degree of freedom for the excitations, and interfering them via Raman coupling, we entangle the two excitations. Via retrieving one excitation, we create the entanglement between the polarization of a single photon and the momentum of the remaining atomic excitation, with a measured fidelity of 0.901(8). The retrieved optical field is verified to be genuine single photons. The realized entanglement may be employed to create entanglement between two distant nodes in a fully heralded way and with a much higher efficiency.

Experimental Time-Resolved Interference with Multiple Photons of Different Colors.

Interference of multiple photons via a linear-optical network has profound applications for quantum foundation, quantum metrology, and quantum computation. Particularly, a boson sampling experiment with a moderate number of photons becomes intractable even for the most powerful classical computers. Scaling up from small-scale experiments requires highly indistinguishable single photons, which may be prohibited for many physical systems. Here we report a time-resolved multiphoton interference experiment by using photons not overlapping in their frequency spectra from three atomic-ensemble quantum memories. Time-resolved measurement enables us to observe nonclassical multiphoton correlation landscapes, which agree well with theoretical calculations. Symmetries in the landscapes are identified to reflect symmetries of the optical network. Our experiment can be further extended to realize boson sampling with many photons and plenty of modes, which thus may provide a route towards quantum supremacy with nonidentical photons.

Time sensitivity factor of single pulmonary nodule: a new cancer characteristic metabolic parameter by (18) F-FDG PET.

OBJECTIVE: To calculate the time sensitivity factor (S) for discriminating the solitary pulmonary nodule (SPN) by FDG PET at different time points. METHODS: The multiple time-point FDG PET images from 41 patients for evaluating SPN seen on chest X-ray or CT were prospectively analyzed to calculate and evaluate S against the gold standard of tissue histology (n = 38) or long term clinicoradiographic follow-up (n = 3). The maximal standardized uptake values (SUV) at the 3 hourly time points were measured. The S was calculated using S = d{ln⁡(SUV)}/d{ln⁡(t)} at 3 different time intervals. ROC analysis of the S parameters was performed to evaluate the optimal cut-off value and their accuracy in classifying the SPN. RESULTS: The SUV in malignant SPN was higher than the corresponding value in benign lesions at all 3 hourly time points (P < 0.003). The S parameters using 3 different time intervals all significantly separated the two groups (P < 0.0005) with an optimal cut-off point near the theoretical value of zero with a high sensitivity of 100% and specificity of 86%. CONCLUSION. The S can be calculated for SPNs using multiple time-point FDG PET, providing a tumor characteristic metabolic parameter with high discrimination power using a simple positive value representing malignancy.

A Chinese herbal formula, Wuzi Yanzong pill, improves spermatogenesis by modulating the secretory function of Sertoli cells.

OBJECTIVE: To evaluate the effects of the Chinese herbal formula Wuzi Yanzong Pill (, WYP) on the spermatogenesis and specific secretory functions of Sertoli cells in rat model and to investigate the underlying mechanism. METHODS: Five groups of male Sprague-Dawley rats including the control group, the model group, the low-dose WYP group, the medium-dose WYP group and the high-dose WYP group (5 in each group) were treated daily with vehicle, multiglycosides of Tripterygium wilfordii Hook f (GTW) either alone (20 mg/kg) or followed by WYP (0.5, 1.0, or 2.0 g/kg daily), respectively for 30 days. Serum levels of follicle-stimulating hormone (FSH), inhibin B (INHB) and testosterone (T) were evaluated using enzyme-linked immunosorbent assay. Androgen-binding protein (ABP) gene expression and transferrin (TF) protein expression in testis tissue specimens of all rats were determined using real-time reverse transcriptase polymerase chain reaction and Western blotting analysis, respectively. Histopathological alterations in the testis were determined using Johnsen's score. RESULTS: The toxicity of GTW towards Sertoli cell secretory functions and spermatogenesis was accompanied by increased serum FSH concentrations and decreased INHB and T concentrations. Upregulated ABP mRNA levels, and decreased TF protein expression and Johnsen's scores were detected in the model group compared with the control group P<0.05 or P<0.01). Oral high-dose WYP administrations to GTW-treated rats effectively alleviated all of the GTW-induced changes in specific secretory functions of Sertoli cells (ABP, INHB and TF). Furthermore, serum T level and Johnsen's score of the testis increased greatly compared with the model group (P<0.01). CONCLUSION: WYP has the ability to improve the spermatogenesis, possibly through modulating the secretory proteins expression of Sertoli cells.