Proposed Scheme to Generate Bright Entangled Photon Pairs by Application of a Quadrupole Field to a Single Quantum Dot.

Entangled photon sources are crucial for quantum optics, quantum sensing, and quantum communication. Semiconductor quantum dots generate on-demand entangled photon pairs via the biexciton-exciton cascade. However, the pair of photons are emitted isotropically in all directions, thus limiting the collection efficiency to a fraction of a percent. Moreover, strain and structural asymmetry in quantum dots lift the degeneracy of the intermediate exciton states in the cascade, thus degrading the measured entanglement fidelity. Here, we propose an approach for generating a pair of entangled photons from a semiconductor quantum dot by application of a quadrupole electrostatic potential. We show that the quadrupole electric field corrects for the spatial asymmetry of the excitonic wave function for any quantum dot dipole orientation and fully erases the fine-structure splitting without compromising the spatial overlap between electrons and holes. Our approach is compatible with nanophotonic structures such as microcavities and nanowires, thus paving the way towards a deterministic source of entangled photons with high fidelity and collection efficiency.

Universal fine-structure eraser for quantum dots.

We analyze the degree of entanglement measurable from a quantum dot via the biexciton-exciton cascade as a function of the exciton fine-structure splitting and the detection time resolution. We show that the time-energy uncertainty relation provides means to measure a high entanglement even in presence of a finite fine-structure splitting when a detection system with high temporal resolution is employed. Still, in many applications it would be beneficial if the fine-structure splitting could be compensated to zero. To solve this problem, we propose an all-optical approach with rotating waveplates to erase this fine-structure splitting completely which should allow obtaining a high degree of entanglement with near-unity efficiency. Our optical approach is possible with current technology and is also compatible with any quantum dot showing fine-structure splitting. This bears the advantage that for example the fine-structure splitting of quantum dots in nanowires and micropillars can be directly compensated without the need for further sample processing.

Endoscopic balloon dilation of benign esophageal strictures in dogs and cats.

Endoscopic balloon dilation of benign esophageal strictures was performed in 18 dogs and 10 cats with a median age of 4 years. Stricture formation was associated with a recent anesthetic episode in 18 patients. Regurgitation was the most common clinical sign and was present a median of 4 weeks before dilation. Most animals had a single stricture; median diameter was 5 mm, and median length was 1 cm. Esophagitis and mucosal fibrosis were detected in 9 patients each. Dilation was performed with progressively increasing diameter balloons, from 6 to 20 mm. After dilation, mucosal hemorrhage was mild to moderate in most patients. Esophageal perforation was the only serious complication and occurred in 1 patient. Postdilation therapy consisted of administration of cimetidine, metoclopramide, sucralfate, and prednisone in most animals. The median number of dilation procedures performed in each animal was 2, with a range of 1-5. The median interval between dilations was 13 days. Stricture diameter markedly increased with subsequent dilations. Median duration of follow-up was 131 weeks. A successful outcome occurred in 88% of patients, with most animals able to eat canned, mashed, or dry food without regurgitation. Mucosal fibrosis was associated with a better clinical response score, while increasing age was weakly associated with fewer dilations. The dilation protocol used in this group of animals was safe and efficacious.

Immune-mediated hemolytic anemia: 70 cases (1988-1996).

Survival times and mortality rates in dogs with idiopathic immune-mediated hemolytic anemia (IMHA) have been infrequently reported in the literature. This study evaluates survival and mortality in a large group of dogs with IMHA. The association of age, sex, and breed with IMHA was evaluated by comparing affected dogs to control dogs admitted to the hospital during the same time period. Treatment regimens were reviewed to determine the effects of different agents upon survival of dogs with IMHA during hospitalization and after discharge. Median survival times for each treatment group were 57 days (prednisone), 28 days (prednisone, cyclophosphamide), 974 days (prednisone, azathioprine), 15 days (prednisone, cyclophosphamide, azathioprine), and one day (no treatment). Overall mortality rate in the population of dogs studied was 70%. Twenty-nine (41.4%) dogs either died or were euthanized while hospitalized. Forty-one (59%) dogs were discharged from the hospital. Of the dogs discharged, 10 died within the first month, another five died within three months, and another five died within a year of discharge due to assumed complications of therapy or relapses of IMHA.

The gastroduodenal effects of buffered aspirin, carprofen, and etodolac in healthy dogs.

Twenty-four healthy mixed-breed dogs were divided into 4 groups. Group 1 received a placebo p.o. q12h, group 2 received an average of 16.5 (15.1-17.8) mg/kg buffered aspirin p.o. q12h, group 3 received an average of 2.2 (2.0-2.4) mg/kg carprofen p.o. q12h, and group 4 received an average of 12.8 (11.7-13.8) mg/kg etodolac p.o. q24h (with a placebo in the PM). All treatments continued for 28 consecutive days. Gastroduodenal endoscopy was performed on days -9, 0, 5, 14, and 28. Multiple gastric biopsies were obtained endoscopically on day -9 to determine each dog's Helicobacter infection status. Four regions in the stomach and 1 region in the proximal duodenum were evaluated endoscopically, and each was assigned a score from 1 to 11. Scores for each region then were summed to give a total score for each endoscopic evaluation. Erosions and submucosal hemorrhages were seen in all dogs receiving aspirin. Only minor gastric lesions were observed in the carprofen, etodolac, and control groups. No adverse clinical signs were noted in any dog given any treatment. Median total score on days 0, 5, 14, and 28, respectively, were as follows: group 1: 5.0, 5.0, 5.0, 5.0; group 2: 5.0, 27.0, 26.0, 27.5; group 3: 5.0, 5.0, 6.0, 5.0, group 4: 5.0, 7.0, 5.0, 5.0. There was no significant difference among dogs receiving carprofen, etodolac, or placebo. The administration of carprofen, etodolac, or placebo to healthy dogs resulted in significantly less gastroduodenal lesion development than in dogs receiving buffered aspirin.

Rectal ganglioneuroma in a dog.

An 18-month-old, spayed female Australian terrier cross was presented with a 10-month history of chronic large bowel diarrhea. Ulceration and two proliferative masses in the rectum were seen on colonoscopy. Surgical resection was performed to remove the masses, and the dog recovered without complications related to surgery. Histopathology was consistent with the diagnosis of ganglioneuroma. The dog had no clinical signs of disease within three months of surgery and was completely normal 2.5 years after diagnosis. This is the first report providing follow-up and successful outcome of a ganglioneuroma in the gastrointestinal tract of a dog.