Single-shot measurement of triplet-singlet relaxation in a Si/SiGe double quantum dot

We investigate the lifetime of two-electron spin states in a few-electron Si/SiGe double dot. At the transition between the (1,1) and (0,2) charge occupations, Pauli spin blockade provides a readout mechanism for the spin state. We use the statistics of repeated single-shot measurements to extract the lifetimes of multiple states simultaneously. When the magnetic field is zero, we find that all three triplet states have equal lifetimes, as expected, and this time is ~10 ms. When the field is nonzero, the T(0) lifetime is unchanged, whereas the T- lifetime increases monotonically with the field, reaching 3 sec at 1 T.

Single-shot correlations and two-qubit gate of solid-state spins

Measurement of coupled quantum systems plays a central role in quantum information processing. We have realized independent single-shot read-out of two electron spins in a double quantum dot. The read-out method is all-electrical, cross-talk between the two measurements is negligible, and read-out fidelities are ~86% on average. This allows us to directly probe the anticorrelations between two spins prepared in a singlet state and to demonstrate the operation of the two-qubit exchange gate on a complete set of basis states. The results provide a possible route to the realization and efficient characterization of multiqubit quantum circuits based on single quantum dot spins.

Hiccups due to gastroesophageal reflux

Hiccups (singultus) are most often a transient phenomenon that resolves without medical therapy. Intractable hiccups can be an indication of a serious underlying disease process and should be investigated. To demonstrate the evaluation of intractable singultus, we describe a patient who had unsuccessful outpatient therapy for persistent hiccups and who was subsequently found to have gastroesophageal reflux (GER). Efforts to determine the cause of the hiccups were negative except for endoscopically proven GER. On follow-up visits, antisingultus medications were withdrawn without return of hiccups, and repeat endoscopy showed substantial healing of the esophagitis. We conclude that GER may be underestimated as a cause of hiccups.

Production, partial purification, and antimicrobial activity of a novel antibiotic produced by a Bacillus subtilis isolate from Ulmus americana

Antibiotic substances produced by a Bacillus subtilis isolate from the xylem of an American elm (Ulmus americana L.) inhibited several fungal plant pathogens including the Dutch elm disease pathogen, Ceratocystis ulrni. Bioassays indicated the bacterium produced a diffusible, methanol-soluble antibiotic on potato dextrose agar at 30 °C. Cellulose powder column chromatography separated the antibiotic, which was further purified on a Sephadex LH-20 column, yielding two peaks of antibiotic activity, BS1 and BS2. These were further purified by paper chromatography. High-performance liquid chromatography, using C-18 reverse phase chromatography under isocratic conditions, resulted in five 280-nm absorbing peaks. Only one peak contained antibiotic activity. Upon ultrafiltration, the antibiotics passed through a 500 mol. wt. filter. The antibiotic was soluble in water, absolute methanol, ethanol, and chloroform but not in hexane or petroleum ether. Antimicrobial activity differed from that of other B. subtilis antibiotics including iturin A, bacillomycin L, mycosubtilin, fengycin, and bacilysin. Ceratocystis ulmi exposed to BS1 produced short, twisted, and swollen hyphae with irregularly thickened cell walls.