Entanglement of Trapped-Ion Qubits Separated by 230 Meters

We report on an elementary quantum network of two atomic ions separated by 230 m. The ions are trapped in different buildings and connected with 520(2) m of optical fiber. At each network node, the electronic state of an ion is entangled with the polarization state of a single cavity photon; subsequent to interference of the photons at a beam splitter, photon detection heralds entanglement between the two ions. Fidelities of up to (88.0+2.2-4.7)% are achieved with respect to a maximally entangled Bell state, with a success probability of 4×10^{-5}. We analyze the routes to improve these metrics, paving the way for long-distance networks of entangled quantum processors.

Extraneural metastasis of medulloblastoma

2065

Background: Medulloblastoma is the most common childhood intracranial tumor to spread extraneurally. Information regarding prognostic factors and best therapeutic approach of extraneural metastasis (ENM) of medulloblastoma is mostly limited to case reports. The purpose of this study was to perform a comprehensive literature review and analysis of reported cases dealing with ENM to identify the characteristics, prognostic factors, optimal treatment modalities, and survival of these patients. Methods: A PubMed search of English language articles from 1963–2007 was performed, yielding 47 articles with 119 patients. Factors analyzed included age, time interval to ENM, CNS involvement at the time of ENM, location of ENM, treatment, and outcome. Results: Location of ENM included bone in 84%, bone marrow in 27%, lung in 6%, liver in 6%, and lymph nodes in 15%. Of patients with available data regarding location of RT after ENM, 87% of patients received this treatment to the site of ENM. The 1-year disease free survival (DFS) and overall survival (OS) after the diagnosis of ENM was 35% and 42%, respectively. The 1-year OS for patients with and without radiotherapy (RT) after ENM was 58% and 35%, respectively (p = 0.019). For patients without CNS involvement at the time of ENM the 1-year OS for those treated with and without RT was 82% and 51%, respectively (p = 0.030), however RT did not significantly improve OS for those with CNS involvement. ENM in the lung or liver was found to be a negative prognostic factor (p = 0.002). 1-year OS of patients with time interval to ENM of <18 months was 25% while those with time interval greater than or equal to 18 months it was 61% (p = 0.001). Conclusions: Negative prognostic factors for patients with ENM include CNS involvement at the time of ENM, lung or liver involvement, and duration to ENM <18 months. Patients without CNS involvement who received RT after ENM had an OS and DFS benefit compared to those not receiving RT.

No significant financial relationships to disclose.