101 research outputs found
Opportunities for lattice QCD in quark and lepton flavor physics
This document is one of a series of whitepapers from the USQCD collaboration.
Here, we discuss opportunities for lattice QCD in quark and lepton flavor
physics. New data generated at Belle II, LHCb, BES III, NA62, KOTO, and
Fermilab E989, combined with precise calculations of the relevant hadronic
physics, may reveal what lies beyond the Standard Model. We outline a path
toward improvements of the precision of existing lattice-QCD calculations and
discuss groundbreaking new methods that allow lattice QCD to access new
observables.Comment: USQCD whitepape
Isolation of Single Donors in ZnO
The shallow donor in zinc oxide (ZnO) is a promising semiconductor spin qubit
with optical access. Single indium donors are isolated in a commercial ZnO
substrate using plasma focused ion beam (PFIB) milling. Quantum emitters are
identified optically by spatial and frequency filtering. The indium donor
assignment is based on the optical bound exciton transition energy and magnetic
dependence. The single donor emission is intensity and frequency stable with a
transition linewidth less than twice the lifetime limit. The isolation of
optically stable single donors post-FIB fabrication is promising for optical
device integration required for scalable quantum technologies based on single
donors in direct band gap semiconductors.Comment: E. R. Hansen and V. Niaouris contributed equally to this work. 13
pages, 11 figure
Contributions to the optical linewidth of shallow donor - bound excitonic transition in ZnO
We study the donor-bound exciton optical linewidth properties of Al, Ga and
In donor ensembles in single-crystal zinc oxide (ZnO). Neutral shallow donors
(D) in ZnO are spin qubits with optical access via the donor-bound exciton
(DX). This spin-photon interface enables applications in quantum
networking, memories and transduction. Essential optical parameters which
impact the spin-photon interface include radiative lifetime, optical
inhomogeneous and homogeneous linewidth and optical depth. The ensemble
photoluminescence linewidth ranges from 4-11 GHz, less than two orders of
magnitude larger than the expected lifetime-limited linewidth. The ensemble
linewidth remains narrow in absorption measurements through the 300
m-thick sample, which has an estimated optical depth up to several
hundred. Homogeneous broadening of the ensemble line due to phonons is
consistent with thermal population relaxation between DX states. This
thermal relaxation mechanism has negligible contribution to the total linewidth
at 2 K. We find that inhomogeneous broadening due to the disordered isotopic
environment in natural ZnO is significant, ranging from 1.9 GHz - 2.2 GHz.
Two-laser spectral anti-hole burning measurements, which can be used to measure
the homogeneous linewidth in an ensemble, however, reveal spectral anti-hole
linewidths similar to the single laser ensemble linewidth. Despite this
broadening, the high homogeneity, large optical depth and potential for isotope
purification indicate that the optical properties of the ZnO donor-bound
exciton are promising for a wide range of quantum technologies and motivate a
need to improve the isotope and chemical purity of ZnO for quantum
technologies.Comment: 22 pages, 12 figure
Properties of donor qubits in ZnO formed by indium ion implantation
Shallow neutral donors (D) in ZnO have emerged as a promising
candidate for solid-state spin qubits. Here, we report on the formation of
D in ZnO via implantation of In and subsequent annealing. The
implanted In donors exhibit optical and spin properties on par with doped donors. The inhomogeneous linewidth of the donor-bound exciton
transition is less than 10 GHz, comparable to the optical linewidth of
In. Longitudinal spin relaxation times () exceed
reported values for Ga donors, indicating that residual In
implantation damage does not degrade . Two laser Raman spectroscopy on the
donor spin reveals the hyperfine interaction of the donor electron with the
spin-9/2 In nuclei. This work is an important step toward the deterministic
formation of In donor qubits in ZnO with optical access to a long-lived nuclear
spin memory
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Miniature structured illumination microscope for in vivo 3D imaging of brain structures with optical sectioning
We present a high-resolution miniature, light-weight fluorescence microscope with electrowetting lens and onboard CMOS for high resolution volumetric imaging and structured illumination for rejection of out-of-focus and scattered light. The miniature microscope (SIMscope3D) delivers structured light using a coherent fiber bundle to obtain optical sectioning with an axial resolution of 18 µm. Volumetric imaging of eGFP labeled cells in fixed mouse brain tissue at depths up to 260 µm is demonstrated. The functionality of SIMscope3D to provide background free 3D imaging is shown by recording time series of microglia dynamics in awake mice at depths up to 120 µm in the brain.
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Apolipoprotein E epsilon 4 (APOE-ε4) genotype is associated with decreased 6-month verbal memory performance after mild traumatic brain injury
Introduction: The apolipoprotein E (APOE) ε4 allele associates with memory impairment in neurodegenerative diseases. Its association with memory after mild traumatic brain injury (mTBI) is unclear. Methods: mTBI patients (Glasgow Coma Scale score 13–15, no neurosurgical intervention, extracranial Abbreviated Injury Scale score ≤1) aged ≥18 years with APOE genotyping results were extracted from the Transforming Research and Clinical Knowledge in Traumatic Brain Injury Pilot (TRACK-TBI Pilot) study. Cohorts determined by APOE-ε4(+/−) were assessed for associations with 6-month verbal memory, measured by California Verbal Learning Test, Second Edition (CVLT-II) subscales: Immediate Recall Trials 1–5 (IRT), Short-Delay Free Recall (SDFR), Short-Delay Cued Recall (SDCR), Long-Delay F
Pre-injury Comorbidities Are Associated With Functional Impairment and Post-concussive Symptoms at 3- and 6-Months After Mild Traumatic Brain Injury: A TRACK-TBI Study
Introduction: Over 70% of traumatic brain injuries (TBI) are classified as mild (mTBI), which present heterogeneously. Associations between pre-injury comorbidities and outcomes are not well-understood, and understanding their status as risk factors may improve mTBI management and prognostication.Methods: mTBI subjects (GCS 13–15) from TRACK-TBI Pilot completing 3- and 6-month functional [Glasgow Outcome Scale-Extended (GOSE)] and post-concussive outcomes [Acute Concussion Evaluation (ACE) physical/cognitive/sleep/emotional subdomains] were extracted. Pre-injury comorbidities >10% incidence were included in regressions for functional disability (GOSE ≤ 6) and post-concussive symptoms by subdomain. Odds ratios (OR) and mean differences (B) were reported. Significance was assessed at p < 0.0083 (Bonferroni correction).Results: In 260 subjects sustaining blunt mTBI, mean age was 44.0-years and 70.4% were male. Baseline comorbidities >10% incidence included psychiatric-30.0%, cardiac (hypertension)-23.8%, cardiac (structural/valvular/ischemic)-20.4%, gastrointestinal-15.8%, pulmonary-15.0%, and headache/migraine-11.5%. At 3- and 6-months separately, 30.8% had GOSE ≤ 6. At 3-months, psychiatric (GOSE ≤ 6: OR = 2.75, 95% CI [1.44–5.27]; ACE-physical: B = 1.06 [0.38–1.73]; ACE-cognitive: B = 0.72 [0.26–1.17]; ACE-sleep: B = 0.46 [0.17–0.75]; ACE-emotional: B = 0.64 [0.25–1.03]), headache/migraine (GOSE ≤ 6: OR = 4.10 [1.67–10.07]; ACE-sleep: B = 0.57 [0.15–1.00]; ACE-emotional: B = 0.92 [0.35–1.49]), and gastrointestinal history (ACE-physical: B = 1.25 [0.41–2.10]) were multivariable predictors of worse outcomes. At 6-months, psychiatric (GOSE ≤ 6: OR = 2.57 [1.38–4.77]; ACE-physical: B = 1.38 [0.68–2.09]; ACE-cognitive: B = 0.74 [0.28–1.20]; ACE-sleep: B = 0.51 [0.20–0.83]; ACE-emotional: B = 0.93 [0.53–1.33]), and headache/migraine history (ACE-physical: B = 1.81 [0.79–2.84]) predicted worse outcomes.Conclusions: Pre-injury psychiatric and pre-injury headache/migraine symptoms are risk factors for worse functional and post-concussive outcomes at 3- and 6-months post-mTBI. mTBI patients presenting to acute care should be evaluated for psychiatric and headache/migraine history, with lower thresholds for providing TBI education/resources, surveillance, and follow-up/referrals.Clinical Trial Registration:www.ClinicalTrials.gov, identifier NCT01565551
Lattice QCD and Particle Physics
Contribution from the USQCD Collaboration to the Proceedings of the US
Community Study on the Future of Particle Physics (Snowmass 2021).Comment: 27 pp. main text, 4 pp. appendices, 30 pp. reference
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