Demonstration of Universal Parametric Entangling Gates on a Multi-Qubit Lattice

We show that parametric coupling techniques can be used to generate selective entangling interactions for multi-qubit processors. By inducing coherent population exchange between adjacent qubits under frequency modulation, we implement a universal gateset for a linear array of four superconducting qubits. An average process fidelity of $\mathcal{F}=93\%$ is estimated for three two-qubit gates via quantum process tomography. We establish the suitability of these techniques for computation by preparing a four-qubit maximally entangled state and comparing the estimated state fidelity against the expected performance of the individual entangling gates. In addition, we prepare an eight-qubit register in all possible bitstring permutations and monitor the fidelity of a two-qubit gate across one pair of these qubits. Across all such permutations, an average fidelity of $\mathcal{F}=91.6\pm2.6\%$ is observed. These results thus offer a path to a scalable architecture with high selectivity and low crosstalk

Intraluminal low-dose rate brachytherapy for malignant endobronchial obstruction.

From October 1985 through October 1989, 87 patients underwent 105 intraluminal brachytherapy treatments for endobronchial or endotracheal malignant tumors. Low-dose rate iridium-192 seeds were used. Of the 60 patients treated for primary lung carcinoma, 52 patients (87%) had previously received full-course external beam radiotherapy to the tumor sites. Ten patients were treated for symptomatic metastatic disease, and one patient had extension of tumor into the trachea from carcinoma of the cervical esophagus. Clinical or bronchoscopic improvement was noted in 42 patients (59%). No significant difference in the response rate was observed between various types of tumor. Patients who were treated with a radiation dose larger than 2500 cGy at a 2 cm radius had a significantly greater response rate (77%) than patients treated with a dose less than 2500 cGy (38%) (p = 0.001). A trend toward better results was apparent in patients who had undergone Nd:YAG laser bronchoscopy in the 2 weeks before brachytherapy. The treatments were well tolerated, and the incidence of serious complications was low and acceptable