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Optical Decoherence And Spectral Diffusion At 1.5 Μm In Er3+: Y2 Sio5 Versus Magnetic Field, Temperature, And Er3+ Concentration, Thomas Böttger, C W. Thiel, Y Sun, R L. Cone
Optical Decoherence And Spectral Diffusion At 1.5 Μm In Er3+: Y2 Sio5 Versus Magnetic Field, Temperature, And Er3+ Concentration, Thomas Böttger, C W. Thiel, Y Sun, R L. Cone
Physics and Astronomy
The mechanisms and effects of spectral diffusion for optical transitions of paramagnetic ions have been explored using the inhomogeneously broadened 1536 nm I15∕24→I13∕24 transition in Er3+:Y2SiO5. Using photon echo spectroscopy, spectral diffusion was measured by observing the evolution of the effective coherence lifetimes over time scales from 1μs to 20 ms for magnetic-field strengths from 0.3 to 6.0 T, temperatures from 1.6 to 6.5 K, and nominal Er3+ concentrations of 0.0015%, 0.005%, and 0.02%. To understand the effect of spectral diffusion on material decoherence for different environmental conditions and material compositions, data and models were compared to identify spectral diffusion …
Spectroscopy And Dynamics Of Er3+: Y2 Si O5 At 1.5 Μm, Thomas Böttger, Y Sun, C W. Thiel, R L. Cone
Spectroscopy And Dynamics Of Er3+: Y2 Si O5 At 1.5 Μm, Thomas Böttger, Y Sun, C W. Thiel, R L. Cone
Physics and Astronomy
We present the results of detailed site-selective spectroscopy performed on the I15∕24↔I13∕24 transition of Er3+:Y2SiO5 at 1.5μm. New determinations of the I13∕24 and I15∕24 crystal-field-level structure for the two crystallographically inequivalent Er3+ sites have been made. The fluorescence dynamics of the metastable I13∕24:Y1 excited state was investigated, showing exponential decays for Er3+ at both crystallographic sites with fluorescence lifetimes of 11.4ms for site 1 and 9.2ms for site 2. Exceptionally sharp inhomogeneous absorption lines of 180, 390, and 510MHz were observed in 0.0015% Er3+:Y2SiO5, 0.005% Er3+:Y2SiO5, and 0.02% Er3+:Y2SiO5 crystals, respectively. The g-values for the lowest energy I15∕24 (Z1) and …
A Cosmic Milestone: Constraints From Metal-Poor Halo Stars On The Cosmological Reionization Epoch, Aparna Venkatesan
A Cosmic Milestone: Constraints From Metal-Poor Halo Stars On The Cosmological Reionization Epoch, Aparna Venkatesan
Physics and Astronomy
Theoretical studies and current observations of the high-redshift intergalactic medium (IGM) indicate that at least two cosmic transitions occur by the time the universe reaches gas metallicities of about 10-3 Z☉. One is the cosmological reionization of the IGM, and the second is the transition from a primordial to present-day mode of star formation. We quantify this relation through new calculations of the ionizing radiation produced in association with the elements carbon, oxygen, and silicon observed in Galactic metal-poor halo stars, which are likely second-generation objects formed in the wake of primordial supernovae. We demonstrate that sufficient …
The Radiative Transport Of Dust In Primordial Galaxies And Second-Generation Star Formation, Aparna Venkatesan, Biman B. Nath, J Shull
The Radiative Transport Of Dust In Primordial Galaxies And Second-Generation Star Formation, Aparna Venkatesan, Biman B. Nath, J Shull
Physics and Astronomy
We investigate the radiativetransport of dust inprimordial galaxies in thepresence of the UVradiation field from thefirst metal-free stars. Wefind that dust createdin the first supernova(SN) explosions can bedriven through the interiorof the SN remnantto accumulate in theSN shells, where second-generationstars may form fromcompressed cooling gas. Thisscenario requires metal-free starsto form continuously overtimescales of up to10 Myr, consistent withrecent estimates. Silicate andgraphite grains, as wellas iron-bearing magnetites, aretransported to the shellsfor reasonable parameter assumptions,but their relative yieldsfrom primordial SNe isan important factor inthe resulting abundance ratios.We compare the resultsof segregated grain transportwith the current nucleosyntheticdata on extremely metal-poorGalactic halo stars. Fossilsignatures …