201 research outputs found

    Electromagnetically Induced Transparency with an Ensemble of Donor-Bound Electron Spins in a Semiconductor

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    We present measurements of electromagnetically induced transparency with an ensemble of donor- bound electrons in low-doped n-GaAs. We used optical transitions from the Zeeman-split electron spin states to a bound trion state in samples with optical densities of 0.3 and 1.0. The electron spin dephasing time T* \approx 2 ns was limited by hyperfine coupling to fluctuating nuclear spins. We also observe signatures of dynamical nuclear polarization, but find these effects to be much weaker than in experiments that use electron spin resonance and related experiments with quantum dots.Comment: 4 pages, 4 figures; Improved analysis of data in Fig. 3, corrected factors of 2 and p

    Phase Separation of Rigid-Rod Suspensions in Shear Flow

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    We analyze the behavior of a suspension of rigid rod-like particles in shear flow using a modified version of the Doi model, and construct diagrams for phase coexistence under conditions of constant imposed stress and constant imposed strain rate, among paranematic, flow-aligning nematic, and log-rolling nematic states. We calculate the effective constitutive relations that would be measured through the regime of phase separation into shear bands. We calculate phase coexistence by examining the stability of interfacial steady states and find a wide range of possible ``phase'' behaviors.Comment: 23 pages 19 figures, revised version to be published in Physical Review

    A Measurement of the CMB Temperature Power Spectrum and Constraints on Cosmology from the SPT-3G 2018 TT/TE/EE Data Set

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    We present a sample-variance-limited measurement of the temperature power spectrum (TTTT) of the cosmic microwave background (CMB) using observations of a  ⁣1500deg2\sim\! 1500 \,\mathrm{deg}^2 field made by SPT-3G in 2018. We report multifrequency power spectrum measurements at 95, 150, and 220GHz covering the angular multipole range 750<3000750 \leq \ell < 3000. We combine this TTTT measurement with the published polarization power spectrum measurements from the 2018 observing season and update their associated covariance matrix to complete the SPT-3G 2018 TT/TE/EETT/TE/EE data set. This is the first analysis to present cosmological constraints from SPT TTTT, TETE, and EEEE power spectrum measurements jointly. We blind the cosmological results and subject the data set to a series of consistency tests at the power spectrum and parameter level. We find excellent agreement between frequencies and spectrum types and our results are robust to the modeling of astrophysical foregrounds. We report results for Λ\LambdaCDM and a series of extensions, drawing on the following parameters: the amplitude of the gravitational lensing effect on primary power spectra ALA_\mathrm{L}, the effective number of neutrino species NeffN_{\mathrm{eff}}, the primordial helium abundance YPY_{\mathrm{P}}, and the baryon clumping factor due to primordial magnetic fields bb. We find that the SPT-3G 2018 T/TE/EET/TE/EE data are well fit by Λ\LambdaCDM with a probability-to-exceed of 15%15\%. For Λ\LambdaCDM, we constrain the expansion rate today to H0=68.3±1.5kms1Mpc1H_0 = 68.3 \pm 1.5\,\mathrm{km\,s^{-1}\,Mpc^{-1}} and the combined structure growth parameter to S8=0.797±0.042S_8 = 0.797 \pm 0.042. The SPT-based results are effectively independent of Planck, and the cosmological parameter constraints from either data set are within <1σ<1\,\sigma of each other. (abridged)Comment: 35 Pages, 17 Figures, 11 Table

    Improving Cosmological Constraints from Galaxy Cluster Number Counts with CMB-cluster-lensing Data: Results from the SPT-SZ Survey and Forecasts for the Future

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    We show the improvement to cosmological constraints from galaxy cluster surveys with the addition of cosmic microwave background (CMB)-cluster lensing data. We explore the cosmological implications of adding mass information from the 3.1 sigma detection of gravitational lensing of the CMB by galaxy clusters to the Sunyaev-Zel'dovich (SZ) selected galaxy cluster sample from the 2500 deg(2) SPT-SZ survey and targeted optical and X-ray follow-up data. In the ACDM model, the combination of the cluster sample with the Planck power spectrum measurements prefers sigma(8) (Omega(m)/0.3)(0.5) = 0.831 +/- 0.020. Adding the cluster data reduces the uncertainty on this quantity by a factor of 1.4, which is unchanged whether the 3.1 sigma CMB-cluster lensing measurement is included or not. We then forecast the impact of CMB-cluster lensing measurements with future cluster catalogs. Adding CMB-cluster lensing measurements to the SZ cluster catalog of the ongoing SPT-3G survey is expected to improve the expected constraint on the dark energy equation of state w by a factor of 1.3 to sigma(w) = 0.19. We find the largest improvements from CMB-cluster lensing measurements to be for sigma(8), where adding CMB-cluster lensing data to the cluster number counts reduces the expected uncertainty on sigma(8) by respective factors of 2.4 and 3.6 for SPT-3G and CMB-S4

    An Improved Measurement of the Secondary Cosmic Microwave Background Anisotropies from the SPT-SZ + SPTpol Surveys

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    We report new measurements of millimeter-wave power spectra in the angular multipole range 200011,0002000 \le \ell \le 11,000 (angular scales 5θ15^\prime \gtrsim \theta \gtrsim 1^\prime). By adding 95 and 150\,GHz data from the low-noise 500 deg2^2 SPTpol survey to the SPT-SZ three-frequency 2540 deg2^2 survey, we substantially reduce the uncertainties in these bands. These power spectra include contributions from the primary cosmic microwave background, cosmic infrared background, radio galaxies, and thermal and kinematic Sunyaev-Zel'dovich (SZ) effects. The data favor a thermal SZ (tSZ) power at 143\,GHz of D3000tSZ=3.42±0.54 μK2D^{\rm tSZ}_{3000} = 3.42 \pm 0.54~ \mu {\rm K}^2 and a kinematic SZ (kSZ) power of D3000kSZ=3.0±1.0 μK2D^{\rm kSZ}_{3000} = 3.0 \pm 1.0~ \mu {\rm K}^2. This is the first measurement of kSZ power at 3σ\ge 3\,\sigma. We study the implications of the measured kSZ power for the epoch of reionization, finding the duration of reionization to be Δzre=1.00.7+1.6\Delta z_{re} = 1.0^{+1.6}_{-0.7} (Δzre<4.1\Delta z_{re}< 4.1 at 95% confidence), when combined with our previously published tSZ bispectrum measurement.Comment: Submitted to ApJ, 16 pages. (revised portions of the introduction and description of bandpower estimation

    Flaring Stars in a Non-targeted mm-wave Survey with SPT-3G

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    We present a flare star catalog from four years of non-targeted millimeter-wave survey data from the South Pole Telescope (SPT). The data were taken with the SPT-3G camera and cover a 1500-square-degree region of the sky from 20h40m0s20^{h}40^{m}0^{s} to 3h20m0s3^{h}20^{m}0^{s} in right ascension and 42-42^{\circ} to 70-70^{\circ} in declination. This region was observed on a nearly daily cadence from 2019-2022 and chosen to avoid the plane of the galaxy. A short-duration transient search of this survey yields 111 flaring events from 66 stars, increasing the number of both flaring events and detected flare stars by an order of magnitude from the previous SPT-3G data release. We provide cross-matching to Gaia DR3, as well as matches to X-ray point sources found in the second ROSAT all-sky survey. We have detected flaring stars across the main sequence, from early-type A stars to M dwarfs, as well as a large population of evolved stars. These stars are mostly nearby, spanning 10 to 1000 parsecs in distance. Most of the flare spectral indices are constant or gently rising as a function of frequency at 95/150/220 GHz. The timescale of these events can range from minutes to hours, and the peak νLν\nu L_{\nu} luminosities range from 102710^{27} to 103110^{31} erg s1^{-1} in the SPT-3G frequency bands

    Measurements of B-mode Polarization of the Cosmic Microwave Background from 500 Square Degrees of SPTpol Data

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    We report a B-mode power spectrum measurement from the cosmic microwave background (CMB) polarization anisotropy observations made using the SPTpol instrument on the South Pole Telescope. This work uses 500 deg2^2 of SPTpol data, a five-fold increase over the last SPTpol B-mode release. As a result, the bandpower uncertainties have been reduced by more than a factor of two, and the measurement extends to lower multipoles: 52<<230152 < \ell < 2301. Data from both 95 and 150 GHz are used, allowing for three cross-spectra: 95 GHz x 95 GHz, 95 GHz x 150 GHz, and 150 GHz x 150 GHz. B-mode power is detected at very high significance; we find P(BB<0)=5.8×1071P(BB < 0) = 5.8 \times 10^{-71}, corresponding to a 18.1σ18.1 \sigma detection of power. An upper limit is set on the tensor-to-scalar ratio, r<0.44r < 0.44 at 95% confidence (the expected 1σ1 \sigma constraint on rr given the measurement uncertainties is 0.22). We find the measured B-mode power is consistent with the Planck best-fit Λ\LambdaCDM model predictions. Scaling the predicted lensing B-mode power in this model by a factor Alens, the data prefer Alens = 1.17±0.131.17 \pm 0.13. These data are currently the most precise measurements of B-mode power at >320\ell > 320.Comment: 16 pages, 4 figures, Submitted to PR
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