Monte Carlo analysis of critical phenomenon of the Ising model on memory stabilizer structures

We calculate the critical temperature of the Ising model on a set of graphs representing a concatenated three-bit error-correction code. The graphs are derived from the stabilizer formalism used in quantum error correction. The stabilizer for a subspace is defined as the group of Pauli operators whose eigenvalues are +1 on the subspace. The group can be generated by a subset of operators in the stabilizer, and the choice of generators determines the structure of the graph. The Wolff algorithm, together with the histogram method and finite-size scaling, is used to calculate both the critical temperature and the critical exponents of each structure. The simulations show that the choice of stabilizer generators, both the number and the geometry, has a large effect on the critical temperature.Comment: 7 pages, 6 figures, 5 table

Detection of Single Ion Spectra by Coulomb Crystal Heating

The coupled motion of ions in a radiofrequency trap has been used to connect the frequency- dependent laser-induced heating of a sympathetically cooled spectroscopy ion with changes in the fluorescence of a laser-cooled control ion. This technique, sympathetic heating spectroscopy, is demonstrated using two isotopes of calcium. In the experiment, a few scattered photons from the spectroscopy ion are transformed into a large deviation from the steady-state fluorescence of the control ion. This allows us to detect an optical transition where the number of scattered photons is below our fluorescence detection limit. Possible applications of the technique to molecular ion spectroscopy are briefly discussed.Comment: 7 Pages,10 Figure

Analytical solution of thermal magnetization on memory stabilizer structures

We return to the question of how the choice of stabilizer generators affects the preservation of information on structures whose degenerate ground state encodes a classical redundancy code. Controlled-not gates are used to transform the stabilizer Hamiltonian into a Hamiltonian consisting of uncoupled single spins and/or pairs of spins. This transformation allows us to obtain an analytical partition function and derive closed form equations for the relative magnetization and susceptibility. These equations are in agreement with the numerical results presented in [arXiv:0907.0394v1] for finite size systems. Analytical solutions show that there is no finite critical temperature, Tc=0, for all of the memory structures in the thermodynamic limit. This is in contrast to the previously predicted finite critical temperatures based on extrapolation. The mismatch is a result of the infinite system being a poor approximation even for astronomically large finite size systems, where spontaneous magnetization still arises below an apparent finite critical temperature. We extend our analysis to the canonical stabilizer Hamiltonian. Interestingly, Hamiltonians with two-body interactions have a higher apparent critical temperature than the many-body Hamiltonian.Comment: 13 pages, 7 figures, analytical solutions of problems studied numerically in arXiv:0907.0394v1 [quant-ph

A study of thin film solid phase microextraction methods for analysis of fluorinated benzoic acids in seawater

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.chroma.2016.01.071 © 2016. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Fluorinated benzoic acids (FBAs) are frequently used as tracers by the oil industry to characterize petroleum reservoirs. The demand for fast, reliable, robust, and sensitive approaches to separate and quantify FBAs in produced water, both in laboratory and field conditions, has not been yet fully satisfied. In this study, for the first time, thin film solid phase microextraction (TF-SPME) is proposed as a versatile sample preparation tool for the determination of FBAs in produced water by pursing two different approaches. First, an automated high throughput TF-SPME method using solvent desorption for fast and simultaneous preparation of multiple samples prior to liquid chromatographic separation and high resolution mass spectrometric detection (LC-MS) of FBAs was demonstrated for routine laboratory analysis. This method was optimized in terms of extraction phase chemistry, sample pH and ionic strength, extraction/desorption times using two representative FBAs (4-FBA and 2,3,4,5-tetra FBA). It incorporates a relatively simple sample pretreatment involving pH adjustment prior to the TF-SPME, and obtained limits of quantification (LOQ) are at the 1.0 ng mL(-1) level. Second, the applicability of TF-SPME for fast mass spectrometric (MS) determination of FBAs with omission of derivatization and gas chromatographic (GC) separation was proven. This second method consists of manual extractions of analytes from seawater samples with a thermally stable TF-SPME membrane and direct thermal desorption of the extracted FBAs to a MS via a thermal desorption unit (TDU). It was demonstrated that the TF-SPME extracts and thermally releases analytes quantitatively and with good reproducibility. This approach opens up the possibility for on-site measurements with portable analyzers

Occurrence of Chlorinated Volatile Organic Compounds (VOCs) in a Sanitary Sewer System: Implications for Assessing Vapor Intrusion Alternative Pathways

Sewer systems have been recently recognized as potentially important exposure pathways to consider during vapor intrusion assessments; however, this pathway has not been well-characterized and there is need for additional information about the occurrence of volatile organic compounds (VOCs) in sewer systems. This paper reports the results of sewer gas sampling conducted in a sanitary sewer over the years of 2014–2017. Sewer gas samples were collected and analyzed using several different techniques, including TO-15 (grab), TO-17 (passive), Radiello® (passive) and a novel continuous monitoring technique, the Autonomous Rugged Optical Multigas Analyzer (AROMA). The applicability of each of the different approaches used in this study is discussed in the context of investigating sanitary sewers as a vapor intrusion alternative pathway. The data confirmed that trichloroethylene (TCE) concentrations in sewer gas were detected adjacent to and extending hundreds of feet away from a previously defined vapor intrusion area, where TCE was a primary contaminant. TCE concentrations detected in sewer gas ranged from non-detect to 1600 μg/m3. Temporal variability was observed in TCE concentrations over timescales that ranged from minutes to months to years at discrete sampling locations. Spatial variability in sewer gas concentrations was also observed throughout the study area. Temporal and spatial variability may be caused by groundwater contamination sources in the study area, as well as sewer gas transport mechanisms

SYMPATHETICAL LASER COOLING OF MOLECULAR IONS TO THE μ\muK REGIME

M. Drewsen, A. Mortensen, R. Martinussen, P. Staanum and J. L. S\oAuthor Institution: School of Chemistry and Biochemistry and Computational Science and Engineering; Division, Georgia Institute of Technology, Atlanta, Georgia 30332, USAThe complexity of molecular spectra prevents direct laser cooling of most molecules. Molecular ions can be indirectly laser-cooled by a Columbic interaction with a neighboring atomic ion. This sympathetic cooling method has been used to lower the temperature of molecular ions ranging from CaO$^{+}$ to C$_{60}^{+}$ to less than 100 mK by Doppler cooling the atomic ions}rensen \textit{Phys.~Rev.~Lett.} \underline{\textbf{93}}, 243201 (2004). V.~L.~Ryjkov, XZ.~Zhao and H.~A.~Schuessler \textit{Phys.~Rev.~A} \underline{\textbf{74}}, 023401 (2006). A.~Ostendorf, C.~B.~Zhang, M.~A.~Wilson, D.~Offenberg, B.~Roth, and S.~Schiller \textit{Phys.~Rev.~Lett.} \underline{\textbf{97}}, 243005 (2006).}. Starting with two ions of Ca$^{+}$ in the trap, we introduce oxygen gas until one CaO$^{+}$ is produced. The motion of a CaO$^{+}$ molecular ion and a Ca$^{+}$ atomic ion are coupled by the Coulomb interaction in the same trap. The frequencies of the normal modes of the atom-molecule crystal are first measured by observing the fluorescence quenching of the Ca$^{+}$ atoms. The normal modes can be cooled to the motional ground state by addressing the sidebands of the Ca$^{+}$ quadrupole transition. The result is an atom-molecule crystal with a translational temperature in the $\mu$K regime

Body Composition of Guatemalan Sugarcane Cutters, WorkerProductivity and Different Work Settings and Conditions

The objective of the study was to determine whether the body composition of rural workers constitutes a limiting factor in their productivi­ty responses to different work situations. Fifty-six Guatemalan sugarcane cutters were measured thrice (PI, P2, P3), at two-month intervals, each point representing different work conditions. Body composition was esti­mated from arm muscle circumference and the mean of four skinfolds. Productivity indicators were: daily tonnage of sugarcane cut, number of days worked per fortnight and gross earnings per fortnight. Analysis of variance of repeated measures was used. Findings showed no significant differences in productivity among workers with different PI body composition. Mean productivity levels differed significantly between periods. Changes in mean skinfold and in arm muscle circumference between periods were generally equal among workers with different PI body composition, and were the same for workers of different ages and heights. Changes in productivity between periods were equal among workers with different body composi­tion. Body composition played no role in how workers changed their pro­ductivity in response to different work settings and conditions