10 research outputs found
Thermalization near integrability in a dipolar quantum Newton's cradle
Isolated quantum many-body systems with integrable dynamics generically do
not thermalize when taken far from equilibrium. As one perturbs such systems
away from the integrable point, thermalization sets in, but the nature of the
crossover from integrable to thermalizing behavior is an unresolved and
actively discussed question. We explore this question by studying the dynamics
of the momentum distribution function in a dipolar quantum Newton's cradle
consisting of highly magnetic dysprosium atoms. This is accomplished by
creating the first one-dimensional Bose gas with strong magnetic dipole-dipole
interactions. These interactions provide tunability of both the strength of the
integrability-breaking perturbation and the nature of the near-integrable
dynamics. We provide the first experimental evidence that thermalization close
to a strongly interacting integrable point occurs in two steps:
prethermalization followed by near-exponential thermalization. Exact numerical
calculations on a two-rung lattice model yield a similar two-timescale process,
suggesting that this is generic in strongly interacting near-integrable models.
Moreover, the measured thermalization rate is consistent with a parameter-free
theoretical estimate, based on identifying the types of collisions that
dominate thermalization. By providing tunability between regimes of integrable
and nonintegrable dynamics, our work sheds light both on the mechanisms by
which isolated quantum many-body systems thermalize, and on the temporal
structure of the onset of thermalization.Comment: 6 figures, 9 pages main text; 12 appendices with 12 figure
2021 KSCCM clinical practice guidelines for pain, agitation, delirium, immobility, and sleep disturbance in the intensive care unit
We revised and expanded the “2010 Guideline for the Use of Sedatives and Analgesics in the Adult Intensive Care Unit (ICU).” We revised the 2010 Guideline based mainly on the 2018 “Clinical Practice Guidelines for the Prevention and Management of Pain, Agitation/Sedation, Delirium, Immobility, and Sleep Disruption (PADIS) in Adult Patients in the ICU,” which was an updated 2013 pain, agitation, and delirium guideline with the inclusion of two additional topics (rehabilitation/mobility and sleep). Since it was not possible to hold face-to-face meetings of panels due to the coronavirus disease 2019 (COVID-19) pandemic, all discussions took place via virtual conference platforms and e-mail with the participation of all panelists. All authors drafted the recommendations, and all panelists discussed and revised the recommendations several times. The quality of evidence for each recommendation was classified as high (level A), moderate (level B), or low/very low (level C), and all panelists voted on the quality level of each recommendation. The participating panelists had no conflicts of interest on related topics. The development of this guideline was independent of any industry funding. The Pain, Agitation/Sedation, Delirium, Immobility (rehabilitation/mobilization), and Sleep Disturbance panels issued 42 recommendations (level A, 6; level B, 18; and level C, 18). The 2021 clinical practice guideline provides up-to-date information on how to prevent and manage pain, agitation/sedation, delirium, immobility, and sleep disturbance in adult ICU patients. We believe that these guidelines can provide an integrated method for clinicians to manage PADIS in adult ICU patients