Non-equilibrium critical scaling and universality in a quantum simulator

Universality and scaling laws are hallmarks of equilibrium phase transitions and critical phenomena. However, extending these concepts to non-equilibrium systems is an outstanding challenge. Despite recent progress in the study of dynamical phases, the universality classes and scaling laws for non-equilibrium phenomena are far less understood than those in equilibrium. In this work, using a trapped-ion quantum simulator with single-ion resolution, we investigate the non-equilibrium nature of critical fluctuations following a quantum quench to the critical point. We probe the scaling of spin fluctuations after a series of quenches to the critical Hamiltonian of a long-range Ising model. With systems of up to 50 spins, we show that the amplitude and timescale of the post-quench fluctuations scale with system size with distinct universal critical exponents. While a generic quench can lead to thermal critical behaviour, we find that a second quench from one critical state to another (i.e. a double quench) results in critical behaviour that does not have an equilibrium counterpart. Our results demonstrate the ability of quantum simulators to explore universal scaling beyond the equilibrium paradigm.Comment: 10 pages, 5 figures. Supplementary information contains 18 pages, 10 figure

Broadband velocity modulation spectroscopy of HfF^+: towards a measurement of the electron electric dipole moment

Precision spectroscopy of trapped HfF^+ will be used in a search for the permanent electric dipole moment of the electron (eEDM). While this dipole moment has yet to be observed, various extensions to the standard model of particle physics (such as supersymmetry) predict values that are close to the current limit. We present extensive survey spectroscopy of 19 bands covering nearly 5000 cm^(-1) using both frequency-comb and single-frequency laser velocity-modulation spectroscopy. We obtain high-precision rovibrational constants for eight electronic states including those that will be necessary for state preparation and readout in an actual eEDM experiment.Comment: 13 pages, 7 figures, 3 table

Absorption Line Survey of H3+ toward the Galactic Center Sources II. Eight Infrared Sources within 30 pc of the Galactic Center

Infrared absorption lines of H3+, including the metastable R(3,3)l line, have been observed toward eight bright infrared sources associated with hot and massive stars located in and between the Galactic Center Cluster and the Quintuplet Cluster 30 pc to the east. The absorption lines with high velocity dispersion arise in the Galaxy's Central Molecular Zone (CMZ) as well as in foreground spiral arms. The temperature and density of the gas in the CMZ, as determined from the relative strengths of the H3+ lines, are T=200-300K and n=50-200cm^-3. The detection of high column densities of H3+ toward all eight stars implies that this warm and diffuse gaseous environment is widespread in the CMZ. The products of the ionization rate and path length for these sight lines are 1000 and 10 times higher than in dense and diffuse clouds in the Galactic disk, respectively, indicating that the ionization rate, zeta, is not less than 10^-15 s^-1 and that L is at least on the order of 50 pc. The warm and diffuse gas is an important component of the CMZ, in addition to the three previously known gaseous environments: (1) cold molecular clouds observed by radio emission of CO and other molecules, (2) hot (T=10^4-10^6K) and highly ionized diffuse gas (n_e=10-100cm^-3) seen in radio recombination lines, far infrared atomic lines, and radio-wave scattering, and (3) ultra-hot (T=10^7-10^8K) X-ray emitting plasma. Its prevalence significantly changes the understanding of the environment of the CMZ. The sight line toward GC IRS 3 is unique in showing an additional H3+ absorption component, which is interpreted as due to either a cloud associated with circumnuclear disk or the "50 km s^-1 cloud" known from radio observations. An infrared pumping scheme is examined as a mechanism to populate the (3,3) metastable level in this cloud.Comment: 15 pages, 5 figures, 4 tables Accepted for publication in the Astrophysical Journa

Rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART): Study protocol for a randomized controlled trial

Background: Acute respiratory distress syndrome (ARDS) is associated with high in-hospital mortality. Alveolar recruitment followed by ventilation at optimal titrated PEEP may reduce ventilator-induced lung injury and improve oxygenation in patients with ARDS, but the effects on mortality and other clinical outcomes remain unknown. This article reports the rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART). Methods/Design: ART is a pragmatic, multicenter, randomized (concealed), controlled trial, which aims to determine if maximum stepwise alveolar recruitment associated with PEEP titration is able to increase 28-day survival in patients with ARDS compared to conventional treatment (ARDSNet strategy). We will enroll adult patients with ARDS of less than 72 h duration. The intervention group will receive an alveolar recruitment maneuver, with stepwise increases of PEEP achieving 45 cmH(2)O and peak pressure of 60 cmH2O, followed by ventilation with optimal PEEP titrated according to the static compliance of the respiratory system. In the control group, mechanical ventilation will follow a conventional protocol (ARDSNet). In both groups, we will use controlled volume mode with low tidal volumes (4 to 6 mL/kg of predicted body weight) and targeting plateau pressure <= 30 cmH2O. The primary outcome is 28-day survival, and the secondary outcomes are: length of ICU stay; length of hospital stay; pneumothorax requiring chest tube during first 7 days; barotrauma during first 7 days; mechanical ventilation-free days from days 1 to 28; ICU, in-hospital, and 6-month survival. ART is an event-guided trial planned to last until 520 events (deaths within 28 days) are observed. These events allow detection of a hazard ratio of 0.75, with 90% power and two-tailed type I error of 5%. All analysis will follow the intention-to-treat principle. Discussion: If the ART strategy with maximum recruitment and PEEP titration improves 28-day survival, this will represent a notable advance to the care of ARDS patients. Conversely, if the ART strategy is similar or inferior to the current evidence-based strategy (ARDSNet), this should also change current practice as many institutions routinely employ recruitment maneuvers and set PEEP levels according to some titration method.Hospital do Coracao (HCor) as part of the Program 'Hospitais de Excelencia a Servico do SUS (PROADI-SUS)'Brazilian Ministry of Healt

Quantum optics for space platforms

10.1364/OPN.23.10.000042Optics and Photonics News231042-49OPPH

Long-term vertigo control in patients after intratympanic gentamicin instillation for Ménière's disease

OBJECTIVES:: To assess long-term vertigo symptom control in patients after intratympanic gentamicin instillation for incapacitating unilateral Méniére's disease. To analyze whether an absent caloric response, as analyzed using electronystagmography after gentamicin treatment, is a good predicator of long-term symptom control. Finally, to quantify the patient's perception of long-term posttreatment handicap. STUDY DESIGN:: A retrospective study from a single institution. All patients underwent a similar fixed-dose and duration protocol of drug instillation. METHODS:: Patients were enrolled in this study, and initial outcomes were assessed according to the American Academy of Otolaryngology-Head and Neck Surgery Committee on Hearing and Equilibrium Guidelines for Reporting Treatment Results in Méniére's Disease (1985 and 1995). In this study, only those patients treated more than 5 years previous were considered. One hundred thirty-two patients were eligible for inclusion. All patients underwent hearing testing and electronystagmography, including caloric testing before and after treatment. Posttreatment handicap and long-term vertigo control were assessed using the Dizziness Handicap Index questionnaire expanded with 5 questions specific for Méniére's disease. RESULTS:: Analysis of results is based on the 63 patients who responded. Forty-four were vertigo-free, whereas 14 continued to experience some degree of vertigo. On average, they described 5 episodes in the immediate 24 months before the study. Of the 44 patients who were asymptomatic, 35 had an absent caloric response. Of the 14 patients who realized some vertigo, 12 had an absent caloric response posttreatment. Of the 63 responders, 44 filled in the Dizziness Handicap Index. Of the 19 who did not, 17 reported that they were vertigo-free. CONCLUSION:: Our current protocol achieves complete or substantial vertigo control in most patients. A significant caloric response reduction has been a consequence in almost all patients, although an absent caloric response is not invariably a predictor of long-term symptom control. Finally, patient-perceived handicap in this long-term follow-up is consistent with that of others followed for a much shorter duration in that those who were vertigo-free volunteered a significantly lower score