Measurement of Linear Stark Interference in 199Hg

We present measurements of Stark interference in the 6$^1S_0$ $\rightarrow$ 6$^3P_1$ transition in $^{199}$Hg, a process whereby a static electric field $E$ mixes magnetic dipole and electric quadrupole couplings into an electric dipole transition, leading to $E$-linear energy shifts similar to those produced by a permanent atomic electric dipole moment (EDM). The measured interference amplitude, $a_{SI}$ = $(a_{M1} + a_{E2})$ = (5.8 $\pm$ 1.5)$\times 10^{-9}$ (kV/cm)$^{-1}$, agrees with relativistic, many-body predictions and confirms that earlier central-field estimates are a factor of 10 too large. More importantly, this study validates the capability of the $^{199}$Hg EDM search apparatus to resolve non-trivial, controlled, and sub-nHz Larmor frequency shifts with EDM-like characteristics.Comment: 4 pages, 4 figures, 1 table; revised in response to reviewer comment

Rapid state purification protocols for a Cooper pair box

We propose techniques for implementing two different rapid state purification schemes, within the constraints present in a superconducting charge qubit system. Both schemes use a continuous measurement of charge (z) measurements, and seek to minimize the time required to purify the conditional state. Our methods are designed to make the purification process relatively insensitive to rotations about the x-axis, due to the Josephson tunnelling Hamiltonian. The first proposed method, based on the scheme of Jacobs [Phys. Rev. A 67, 030301(R) (2003)] uses the measurement results to control bias (z) pulses so as to rotate the Bloch vector onto the x-axis of the Bloch sphere. The second proposed method, based on the scheme of Wiseman and Ralph [New J. Phys. 8, 90 (2006)] uses a simple feedback protocol which tightly rotates the Bloch vector about an axis almost parallel with the measurement axis. We compare the performance of these and other techniques by a number of different measures.Comment: 14 pages, 14 figures. v2: Revised version after referee comments. Accepted for publication by Physical Review

Improved limit on the permanent electric dipole moment of 199Hg

We report the results of a new experimental search for a permanent electric dipole moment of 199Hg utilizing a stack of four vapor cells. We find d(199Hg) = (0.49 \pm 1.29_stat \pm 0.76_syst) x 10^{-29} e cm, and interpret this as a new upper bound, |d(199Hg)| < 3.1 x 10^{-29} e cm (95% C.L.). This result improves our previous 199Hg limit by a factor of 7, and can be used to set new constraints on CP violation in physics beyond the standard model.Comment: 4 pages, 4 figures. additional reference, minor edits in response to reviewer comment

Derivation of tropospheric methane from TCCON CH₄ and HF total column observations

The Total Carbon Column Observing Network (TCCON) is a global ground-based network of Fourier transform spectrometers that produce precise measurements of column-averaged dry-air mole fractions of atmospheric methane (CH₄). Temporal variability in the total column of CH₄ due to stratospheric dynamics obscures fluctuations and trends driven by tropospheric transport and local surface fluxes that are critical for understanding CH₄ sources and sinks. We reduce the contribution of stratospheric variability from the total column average by subtracting an estimate of the stratospheric CH₄ derived from simultaneous measurements of hydrogen fluoride (HF). HF provides a proxy for stratospheric CH₄ because it is strongly correlated to CH₄ in the stratosphere, has an accurately known tropospheric abundance (of zero), and is measured at most TCCON stations. The stratospheric partial column of CH₄ is calculated as a function of the zonal and annual trends in the relationship between CH₄ and HF in the stratosphere, which we determine from ACE-FTS satellite data. We also explicitly take into account the CH₄ column averaging kernel to estimate the contribution of stratospheric CH₄ to the total column. The resulting tropospheric CH₄ columns are consistent with in situ aircraft measurements and augment existing observations in the troposphere

Archeological Impact Evaluations and Surveys in the Texas Department of Transportation\u27s Corpus Christi, Laredo, Pharr, and San Antonio Districts 2003-2005

This document constitutes the final report of work done by Prewitt and Associates, Inc. (PAI), under a contract from the Texas Department of Transportation (TxDOT) to provide archeological services in four TxDOT districts—Corpus Christi, Laredo, Pharr, and San Antonio. Under this contract, PAI completed Impact Evaluations and Surveys to assist TxDOT in meeting the requirements of their Memorandum of Understanding with the Texas Historical Commission and a Programmatic Agreement between the Advisory Council on Historic Preservation, the Federal Highway Administration, the Texas Historical Commission, and TxDOT. The contract began on March 17, 2003, and the last work authorization was issued on February 17, 2005. During those two years, fieldwork was done under 33 work authorizations. The 33 work authorizations consisted of 53 Impact Evaluations, 33 Surveys, and 2 Surveys with Geoarcheological Evaluation. Combined, these work authorizations entailed efforts at 47 bridge replacements, 4 bridge rehabilitation projects, 2 locations where new bridges will be built, 20 road rehabilitation or widening projects (many also involving bridge replacements or upgrades), 1 interstate highway rest area replacement, 3 drainage improvement projects, 2 curve realignment projects, 3 projects involving construction of new roads, 1 project involving construction of a railroad grade separation, 1 pedestrian bridge construction project, 1 project involving construction of a water taxi landing, 1 project involving construction of a hike-and-bike trail, 1 project involving modification of a highway interchange, and 1 project involving documentation of an archeological site disturbed by placement of a buried utility line. During completion of these work authorizations, 26 newly discovered or previously recorded archeological sites were investigated, although in the case of 9 previously recorded sites, no archeological remains were observed in the areas that will be impacted by the proposed Transportation Activities. Three of the Impact Evaluations led to recommendations that survey could be needed before construction, in some cases depending on whether new right of way would be required. The other 50 Impact Evaluations resulted in recommendations that no survey be required before construction based on the limited potential for sites with good integrity. Thirteen of the Surveys investigated a total of 3 newly recorded and 12 previously recorded sites. Of these 15 sites, 1 was considered eligible for listing in the National Register of Historic Places and designation as a State Archeological Landmark, and 1 was recommended as needing testing to assess eligibility. The other 33 Surveys either did not find any archeological sites, or they investigated sites that could be assessed as ineligible for National Register listing and State Archeological Landmark designation using the survey data. The records and artifacts generated by the project are curated at the Texas Archeological Research Laboratory