Demonstration of Robust Quantum Gate Tomography via Randomized Benchmarking

Typical quantum gate tomography protocols struggle with a self-consistency problem: the gate operation cannot be reconstructed without knowledge of the initial state and final measurement, but such knowledge cannot be obtained without well-characterized gates. A recently proposed technique, known as randomized benchmarking tomography (RBT), sidesteps this self-consistency problem by designing experiments to be insensitive to preparation and measurement imperfections. We implement this proposal in a superconducting qubit system, using a number of experimental improvements including implementing each of the elements of the Clifford group in single `atomic' pulses and custom control hardware to enable large overhead protocols. We show a robust reconstruction of several single-qubit quantum gates, including a unitary outside the Clifford group. We demonstrate that RBT yields physical gate reconstructions that are consistent with fidelities obtained by randomized benchmarking

The effect of HIV counselling and testing on HIV acquisition in sub-Saharan Africa: a systematic review

Annually, millions of people in sub-Saharan Africa (SSA) receive HIV counselling and testing (HCT), a service designed to inform persons of their HIV status and, if HIV-uninfected, reduce HIV acquisition risk. However, the impact of HCT on HIV acquisition has not been systematically evaluated. We conducted a systematic review to assess this relationship in SSA

Interstellar Carbodiimide (HNCNH) - A New Astronomical Detection from the GBT PRIMOS Survey via Maser Emission Features

In this work, we identify carbodiimide (HNCNH), which is an isomer of the well-known interstellar species cyanamide (NH2CN), in weak maser emission, using data from the GBT PRIMOS survey toward Sgr B2(N). All spectral lines observed are in emission and have energy levels in excess of 170 K, indicating that the molecule likely resides in relatively hot gas that characterizes the denser regions of this star forming region. The anticipated abundance of this molecule from ice mantle experiments is ~10% of the abundance of NH2CN, which in Sgr B2(N) corresponds to ~2 x 10^13 cm-2. Such an abundance results in transition intensities well below the detection limit of any current astronomical facility and, as such, HNCNH could only be detected by those transitions which are amplified by masing.Comment: Accepted in The Astrophysical Journal Letters, 13 pages, 2 figures, generated using AAS LaTeX Macros v 5.

Science with an ngVLA: Observing the Effects of Chemistry on Exoplanets and Planet Formation

One of the primary mechanisms for inferring the dynamical history of planets in our Solar System and in exoplanetary systems is through observation of elemental ratios (i.e. C/O). The ability to effectively use these observations relies critically on a robust understanding of the chemistry and evolutionary history of the observed abundances. Significant efforts have been devoted to this area from within astrochemistry circles, and these efforts should be supported going forward by the larger exoplanetary science community. In addition, the construction of a next-generation radio interferometer will be required to test many of these predictive models in situ, while simultaneously providing the resolution necessary to pinpoint the location of planets in formation.Comment: To be published in the ASP Monograph Series, "Science with a Next-Generation VLA", ed. E. J. Murphy (ASP, San Francisco, CA

CSO and CARMA Observations of L1157. II. Chemical Complexity in the Shocked Outflow

L1157, a molecular dark cloud with an embedded Class 0 protostar possessing a bipolar outflow, is an excellent source for studying shock chemistry, including grain-surface chemistry prior to shocks, and post-shock, gas-phase processing. The L1157-B1 and B2 positions experienced shocks at an estimated ~2000 and 4000 years ago, respectively. Prior to these shock events, temperatures were too low for most complex organic molecules to undergo thermal desorption. Thus, the shocks should have liberated these molecules from the ice grain-surfaces en masse, evidenced by prior observations of SiO and multiple grain mantle species commonly associated with shocks. Grain species, such as OCS, CH3OH, and HNCO, all peak at different positions relative to species that are preferably formed in higher velocity shocks or repeatedly-shocked material, such as SiO and HCN. Here, we present high spatial resolution (~3") maps of CH3OH, HNCO, HCN, and HCO+ in the southern portion of the outflow containing B1 and B2, as observed with CARMA. The HNCO maps are the first interferometric observations of this species in L1157. The maps show distinct differences in the chemistry within the various shocked regions in L1157B. This is further supported through constraints of the molecular abundances using the non-LTE code RADEX (Van der Tak et al. 2007). We find the east/west chemical differentiation in C2 may be explained by the contrast of the shock's interaction with either cold, pristine material or warm, previously-shocked gas, as seen in enhanced HCN abundances. In addition, the enhancement of the HNCO abundance toward the the older shock, B2, suggests the importance of high-temperature O-chemistry in shocked regions.Comment: Accepted for publication in the Astrophysical Journa

CSO and CARMA Observations of L1157. I. A Deep Search for Hydroxylamine (NH2_2OH)

A deep search for the potential glycine precursor hydroxylamine (NH$_2$OH) using the Caltech Submillimeter Observatory (CSO) at $\lambda = 1.3$ mm and the Combined Array for Research in Millimeter-wave Astronomy (CARMA) at $\lambda = 3$ mm is presented toward the molecular outflow L1157, targeting the B1 and B2 shocked regions. We report non-detections of NH$_2$OH in both sources. We a perform non-LTE analysis of CH$_3$OH observed in our CSO spectra to derive kinetic temperatures and densities in the shocked regions. Using these parameters, we derive upper limit column densities of NH$_2$OH of $\leq1.4 \times 10^{13}$~cm$^{-2}$ and $\leq1.5 \times 10^{13}$~cm$^{-2}$ toward the B1 and B2 shocks, respectively, and upper limit relative abundances of $N_{NH_2OH}/N_{H_2} \leq1.4 \times 10^{-8}$ and $\leq1.5 \times 10^{-8}$, respectively.Comment: Accepted in the Astrophysical Journa

Field measurements of trace gases and aerosols emitted by peat fires in Central Kalimantan, Indonesia, during the 2015 El Nino

Abstract. Peat fires in Southeast Asia have become a major annual source of trace gases and particles to the regional–global atmosphere. The assessment of their influence on atmospheric chemistry, climate, air quality, and health has been uncertain partly due to a lack of field measurements of the smoke characteristics. During the strong 2015 El Niño event we deployed a mobile smoke sampling team in the Indonesian province of Central Kalimantan on the island of Borneo and made the first, or rare, field measurements of trace gases, aerosol optical properties, and aerosol mass emissions for authentic peat fires burning at various depths in different peat types. This paper reports the trace gas and aerosol measurements obtained by Fourier transform infrared spectroscopy, whole air sampling, photoacoustic extinctiometers (405 and 870 nm), and a small subset of the data from analyses of particulate filters. The trace gas measurements provide emission factors (EFs; grams of a compound per kilogram biomass burned) for up to  ∼  90 gases, including CO2, CO, CH4, non-methane hydrocarbons up to C10, 15 oxygenated organic compounds, NH3, HCN, NOx, OCS, HCl, etc. The modified combustion efficiency (MCE) of the smoke sources ranged from 0.693 to 0.835 with an average of 0.772 ± 0.053 (n  =  35), indicating essentially pure smoldering combustion, and the emissions were not initially strongly lofted. The major trace gas emissions by mass (EF as g kg−1) were carbon dioxide (1564 ± 77), carbon monoxide (291 ± 49), methane (9.51 ± 4.74), hydrogen cyanide (5.75 ± 1.60), acetic acid (3.89 ± 1.65), ammonia (2.86 ± 1.00), methanol (2.14 ± 1.22), ethane (1.52 ± 0.66), dihydrogen (1.22 ± 1.01), propylene (1.07 ± 0.53), propane (0.989 ± 0.644), ethylene (0.961 ± 0.528), benzene (0.954 ± 0.394), formaldehyde (0.867 ± 0.479), hydroxyacetone (0.860 ± 0.433), furan (0.772 ± 0.035), acetaldehyde (0.697 ± 0.460), and acetone (0.691 ± 0.356). These field data support significant revision of the EFs for CO2 (−8 %), CH4 (−55 %), NH3 (−86 %), CO (+39 %), and other gases compared with widely used recommendations for tropical peat fires based on a lab study of a single sample published in 2003. BTEX compounds (benzene, toluene, ethylbenzene, xylenes) are important air toxics and aerosol precursors and were emitted in total at 1.5 ± 0.6 g kg−1. Formaldehyde is probably the air toxic gas most likely to cause local exposures that exceed recommended levels. The field results from Kalimantan were in reasonable agreement with recent lab measurements of smoldering Kalimantan peat for “overlap species,” lending importance to the lab finding that burning peat produces large emissions of acetamide, acrolein, methylglyoxal, etc., which were not measurable in the field with the deployed equipment and implying value in continued similar efforts. The aerosol optical data measured include EFs for the scattering and absorption coefficients (EF Bscat and EF Babs, m2 kg−1 fuel burned) and the single scattering albedo (SSA) at 870 and 405 nm, as well as the absorption Ångström exponents (AAE). By coupling the absorption and co-located trace gas and filter data we estimated black carbon (BC) EFs (g kg−1) and the mass absorption coefficient (MAC, m2 g−1) for the bulk organic carbon (OC) due to brown carbon (BrC). Consistent with the minimal flaming, the emissions of BC were negligible (0.0055 ± 0.0016 g kg−1). Aerosol absorption at 405 nm was  ∼  52 times larger than at 870 nm and BrC contributed  ∼  96 % of the absorption at 405 nm. Average AAE was 4.97 ± 0.65 (range, 4.29–6.23). The average SSA at 405 nm (0.974 ± 0.016) was marginally lower than the average SSA at 870 nm (0.998 ± 0.001). These data facilitate modeling climate-relevant aerosol optical properties across much of the UV/visible spectrum and the high AAE and lower SSA at 405 nm demonstrate the dominance of absorption by the organic aerosol. Comparing the Babs at 405 nm to the simultaneously measured OC mass on filters suggests a low MAC ( ∼  0.1) for the bulk OC, as expected for the low BC/OC ratio in the aerosol. The importance of pyrolysis (at lower MCE), as opposed to glowing (at higher MCE), in producing BrC is seen in the increase of AAE with lower MCE (r2 =  0.65)