Phonon-Induced Rabi-Frequency Renormalization of Optically Driven Single InGaAs/GaAs Quantum Dots

The authors thank the EPSRC (U.K.) EP/G001642, and the QIPIRC U.K. for financial support. A. N. is supported by the EPSRC and B.W. L. by the Royal Society.We study optically driven Rabi rotations of a quantum dot exciton transition between 5 and 50 K, and for pulse areas of up to 14 pi. In a high driving field regime, the decay of the Rabi rotations is nonmonotonic, and the period decreases with pulse area and increases with temperature. By comparing the experiments to a weak-coupling model of the exciton-phonon interaction, we demonstrate that the observed renormalization of the Rabi frequency is induced by fluctuations in the bath of longitudinal acoustic phonons, an effect that is a phonon analogy of the Lamb shift.Peer reviewe

Quantum capacitance and charge sensing of a superconducting double dot

We acknowledge the support from Hitachi Cambridge Laboratory and EPSRC Grant No. EP/K027018/1. A.J.F. is supported by a Hitachi Research fellowship.We study the energetics of a superconducting double dot, by measuring both the quantum capacitance of the device and the response of a nearby charge sensor. We observe different behaviour for odd and even charge states and describe this with a model based on the competition between the charging energy and the superconducting gap. We also find that, at finite temperatures, thermodynamic considerations have a significant effect on the charge stability diagram.PostprintPeer reviewe

Sub-Doppler laser cooling of 40K with Raman gray molasses on the D2 line

Gray molasses is a powerful tool for sub-Doppler laser cooling of atoms to low temperatures. For alkaline atoms, this technique is commonly implemented with cooling lasers which are blue-detuned from either the D1 or D2 line. Here we show that efficient gray molasses can be implemented on the D2 line of 40K with red-detuned lasers. We obtained temperatures of 48(2)µK, which enables direct loading of 9.2(3)x106 atoms from a magneto-optical trap into an optical dipole trap. We support our findings by a one-dimensional model and three-dimensional numerical simulations of the optical Bloch equations which qualitatively reproduce the experimentally observed cooling effects.PreprintPublisher PDFPeer reviewe

Baroreflex Activation Therapy for the Treatment of Heart Failure With a Reduced Ejection Fraction

AbstractObjectivesThe objective of this clinical trial was to assess the safety and efficacy of carotid BAT in advanced HF.BackgroundIncreased sympathetic and decreased parasympathetic activity contribute to heart failure (HF) symptoms and disease progression. Baroreflex activation therapy (BAT) results in centrally mediated reduction of sympathetic outflow and increased parasympathetic activity.MethodsPatients with New York Heart Association (NYHA) functional class III HF and ejection fractions ≤35% on chronic stable guideline-directed medical therapy (GDMT) were enrolled at 45 centers in the United States, Canada, and Europe. They were randomly assigned to receive ongoing GDMT alone (control group) or ongoing GDMT plus BAT (treatment group) for 6 months. The primary safety end point was system- and procedure-related major adverse neurological and cardiovascular events. The primary efficacy end points were changes in NYHA functional class, quality-of-life score, and 6-minute hall walk distance.ResultsOne hundred forty-six patients were randomized, 70 to control and 76 to treatment. The major adverse neurological and cardiovascular event–free rate was 97.2% (lower 95% confidence bound 91.4%). Patients assigned to BAT, compared with control group patients, experienced improvements in the distance walked in 6 min (59.6 ± 14 m vs. 1.5 ± 13.2 m; p = 0.004), quality-of-life score (–17.4 ± 2.8 points vs. 2.1 ± 3.1 points; p < 0.001), and NYHA functional class ranking (p = 0.002 for change in distribution). BAT significantly reduced N-terminal pro–brain natriuretic peptide (p = 0.02) and was associated with a trend toward fewer days hospitalized for HF (p = 0.08).ConclusionsBAT is safe and improves functional status, quality of life, exercise capacity, N-terminal pro–brain natriuretic peptide, and possibly the burden of heart failure hospitalizations in patients with GDMT-treated NYHA functional class III HF. (Barostim Neo System in the Treatment of Heart Failure; NCT01471860; Barostim HOPE4HF [Hope for Heart Failure] Study; NCT01720160

Wastewater Surveillance for SARS-CoV-2 on College Campuses: Initial Efforts, Lessons Learned, and Research Needs

Wastewater surveillance for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emerging approach to help identify the risk of a coronavirus disease (COVID-19) outbreak. This tool can contribute to public health surveillance at both community (wastewater treatment system) and institutional (e.g., colleges, prisons, and nursing homes) scales. This paper explores the successes, challenges, and lessons learned from initial wastewater surveillance efforts at colleges and university systems to inform future research, development and implementation. We present the experiences of 25 college and university systems in the United States that monitored campus wastewater for SARS-CoV-2 during the fall 2020 academic period. We describe the broad range of approaches, findings, resources, and impacts from these initial efforts. These institutions range in size, social and political geographies, and include both public and private institutions. Our analysis suggests that wastewater monitoring at colleges requires consideration of local information needs, sewage infrastructure, resources for sampling and analysis, college and community dynamics, approaches to interpretation and communication of results, and follow-up actions. Most colleges reported that a learning process of experimentation, evaluation, and adaptation was key to progress. This process requires ongoing collaboration among diverse stakeholders including decision-makers, researchers, faculty, facilities staff, students, and community members