Quantum Control of Cold Atoms using microwaves

Projecte final de Màster Oficial fet en col.laboració amb Universitat Autònoma de Barcelona (UAB), Universitat de Barcelona (UB)i Institut de Ciències Fotòniques (ICFO)English: We study quantum control of the ground hyperfine manifold of alkali-metal atoms based on applied microwave fields. We performed microwave spectroscopy both in the frequency and the time domain resulting in the observation of spectra and Rabi oscillations. We also apply a spin echo technique to characterize the coherence time of our trapped atoms.Castellà: En este proyecto estudiamos el control cuántico del estado fundamental de átomos alcalinos bajo la aplicación de campos de microondas. Se realiza espectroscopía de microondas tanto en la frecuencia como en tiempo resultante en la observación de los espectros y de oscilaciones de Rabi. También aplicamos una variante de la técnica de eco de spin para caracterizar el tiempo de la coherencia de nuestros átomos atrapados.Català: En aquest projecte estudiem el control quàntic de l'estat fonamental d'àtoms alcalins sota l'aplicació de camps de microones. Es realitzar espectroscòpia de microones tant en la freqüència com en temps resultant en l'observació dels espectres i d'oscil·lacions de Rabi. També apliquem una variant de la tècnica d'eco d'spin per caracteritzar el temps de la coherència dels nostres àtoms atrapats

Quantum atom-light interfaces in the gaussian description for spin-1 systems

We extend the covariance-matrix description of atom--light quantum interfaces, originally developed for real and effective spin-1/2 atoms, to include "spin alignment" degrees of freedom. This allows accurate modeling of optically-probed spin-1 ensembles in arbitrary magnetic fields. We also include technical noise terms that are very common in experimental situations. These include magnetic field noise, variable atom number and the effect of magnetic field inhomogeneities. We demonstrate the validity of our extended model by comparing numerical simulations to a free--induction decay (FID) measurement of polarized $^{87}$Rb atoms in the $f = 1$ ground state. We qualitatively and quantitatively reproduce experimental results with all free parameters of the simulations fixed. The model can be easily extended to larger spin systems, and adapted to more complicated experimental situations.Comment: 25 pages, 4 figure

Quantum Control of Cold Atoms using microwaves

Projecte final de Màster Oficial fet en col.laboració amb Universitat Autònoma de Barcelona (UAB), Universitat de Barcelona (UB)i Institut de Ciències Fotòniques (ICFO)English: We study quantum control of the ground hyperfine manifold of alkali-metal atoms based on applied microwave fields. We performed microwave spectroscopy both in the frequency and the time domain resulting in the observation of spectra and Rabi oscillations. We also apply a spin echo technique to characterize the coherence time of our trapped atoms.Castellà: En este proyecto estudiamos el control cuántico del estado fundamental de átomos alcalinos bajo la aplicación de campos de microondas. Se realiza espectroscopía de microondas tanto en la frecuencia como en tiempo resultante en la observación de los espectros y de oscilaciones de Rabi. También aplicamos una variante de la técnica de eco de spin para caracterizar el tiempo de la coherencia de nuestros átomos atrapados.Català: En aquest projecte estudiem el control quàntic de l'estat fonamental d'àtoms alcalins sota l'aplicació de camps de microones. Es realitzar espectroscòpia de microones tant en la freqüència com en temps resultant en l'observació dels espectres i d'oscil·lacions de Rabi. També apliquem una variant de la tècnica d'eco d'spin per caracteritzar el temps de la coherència dels nostres àtoms atrapats

Quantum atom-light interfaces in the Gaussian description for spin-1 systems

We extend the covariance matrix description of atom–light quantum interfaces, originally developed for real and effective spin-1/2 atoms, to include ‘spin alignment’ degrees of freedom. This allows accurate modelling of optically probed spin-1 ensembles in arbitrary magnetic fields. We also include technical noise terms that are very common in experimental situations. These include magnetic field noise, variable atom number and the effect of magnetic field inhomogeneities. We demonstrate the validity of our extended model by comparing numerical simulations to a free–induction decay measurement of polarized 87Rb atoms in the f = 1 ground state. We qualitatively and quantitatively reproduce experimental results with no free parameters. The model can be easily extended to larger spin systems, and adapted to more complicated experimental situations

Subcutaneous anti-COVID-19 hyperimmune immunoglobulin for prevention of disease in asymptomatic individuals with SARS-CoV-2 infection: a double-blind, placebo-controlled, randomised clinical trialResearch in context

Summary: Background: Anti-COVID-19 hyperimmune immunoglobulin (hIG) can provide standardized and controlled antibody content. Data from controlled clinical trials using hIG for the prevention or treatment of COVID-19 outpatients have not been reported. We assessed the safety and efficacy of subcutaneous anti-COVID-19 hyperimmune immunoglobulin 20% (C19-IG20%) compared to placebo in preventing development of symptomatic COVID-19 in asymptomatic individuals with SARS-CoV-2 infection. Methods: We did a multicentre, randomized, double-blind, placebo-controlled trial, in asymptomatic unvaccinated adults (≥18 years of age) with confirmed SARS-CoV-2 infection within 5 days between April 28 and December 27, 2021. Participants were randomly assigned (1:1:1) to receive a blinded subcutaneous infusion of 10 mL with 1 g or 2 g of C19-IG20%, or an equivalent volume of saline as placebo. The primary endpoint was the proportion of participants who remained asymptomatic through day 14 after infusion. Secondary endpoints included the proportion of individuals who required oxygen supplementation, any medically attended visit, hospitalisation, or ICU, and viral load reduction and viral clearance in nasopharyngeal swabs. Safety was assessed as the proportion of patients with adverse events. The trial was terminated early due to a lack of potential benefit in the target population in a planned interim analysis conducted in December 2021. ClinicalTrials.gov registry: NCT04847141. Findings: 461 individuals (mean age 39.6 years [SD 12.8]) were randomized and received the intervention within a mean of 3.1 (SD 1.27) days from a positive SARS-CoV-2 test. In the prespecified modified intention-to-treat analysis that included only participants who received a subcutaneous infusion, the primary outcome occurred in 59.9% (91/152) of participants receiving 1 g C19-IG20%, 64.7% (99/153) receiving 2 g, and 63.5% (99/156) receiving placebo (difference in proportions 1 g C19-IG20% vs. placebo, −3.6%; 95% CI -14.6% to 7.3%, p = 0.53; 2 g C19-IG20% vs placebo, 1.1%; −9.6% to 11.9%, p = 0.85). None of the secondary clinical efficacy endpoints or virological endpoints were significantly different between study groups. Adverse event rate was similar between groups, and no severe or life-threatening adverse events related to investigational product infusion were reported. Interpretation: Our findings suggested that administration of subcutaneous human hyperimmune immunoglobulin C19-IG20% to asymptomatic individuals with SARS-CoV-2 infection was safe but did not prevent development of symptomatic COVID-19. Funding: Grifols