Bounding quantum gate error rate based on reported average fidelity

Remarkable experimental advances in quantum computing are exemplified by recent announcements of impressive average gate fidelities exceeding 99.9% for single-qubit gates and 99% for two-qubit gates. Although these high numbers engender optimism that fault-tolerant quantum computing is within reach, the connection of average gate fidelity with fault-tolerance requirements is not direct. Here we use reported average gate fidelity to determine an upper bound on the quantum-gate error rate, which is the appropriate metric for assessing progress towards fault-tolerant quantum computation, and we demonstrate that this bound is asymptotically tight for general noise. Although this bound is unlikely to be saturated by experimental noise, we demonstrate using explicit examples that the bound indicates a realistic deviation between the true error rate and the reported average fidelity. We introduce the Pauli distance as a measure of this deviation, and we show that knowledge of the Pauli distance enables tighter estimates of the error rate of quantum gates.Comment: New Journal of Physics Fast Track Communication. Gold open access journa

Stalled!: Transforming Public Restrooms

Joel Sanders interrogates the intersections of architecture, public space, gender and sexuality with his project for public restrooms Stalled!. Stalled! involves an interdisciplinary design research project in which Sanders collaborates together with gender studies professor Susan Stryker, and law professor Terry Kogan. Stalled! proposes to regard access to public restrooms as a social justice issue with design consequences that can be solved with innovative architectural solutions. The project aims to create restrooms that not only meet the needs of the trans community, but encompass the needs of all embodied subjects of different ages, genders and abilities

Heat conduction in the cable insulation of force-cooled underground electrical power transmission systems

Forced cooling of underground electric power transmission lines, pt.2Forced-cooled systems for oil-filled pipe-type cable circuits have recently been considered. In such systems the conduction resistance through the paper insulation of the cables is the limiting thermal resistance. Assuming bilateral symmetry, steady-state conditions, and two-dimensional heat transfer, a FORTRAN IV computer program was written to solve the heat conduction problem in the cable insulation for arbitrary configurations of a three-cable system. For a steel pipe, a cable system is most susceptible to overheating in the equilateral configuration with the three cables touching. Proximity effects are very significant in forced cooling, especially when cables are not provided with a copper tape under the insulation moisture seal assembly, accounting for as much as 21% of the total oil temperature rise between refrigeration stations. This figure, however, is reduced to 8% when 0.005 inch thick copper tape is present.Consolidated Edison Co. of New Yor

The Search for the Missing Baryons at Low Redshift

At low redshift, only about one-tenth of the known baryons lie in galaxies or the hot gas seen in galaxy clusters and groups. Models posit that these "missing baryons" are in gaseous form in overdense filaments that connect the much denser virialized groups and clusters. About 30% are cool (<1E5 K) and are detected in Ly alpha absorption studies, but about half is predicted to lie in the 1E5-1E7 K regime. Gas is detected in the 2-5E5 K range through OVI absorption studies (7% of the baryons) and possibly near 1E5 K from broad Ly absorption (20% of the baryons). Hotter gas (0.5-2E6 K) is detected at zero redshift by OVII and OVIII K X-ray absorption, and the OVII line strengths seem to correlate with the Galactic soft X-ray background, so it is probably produced by Galactic Halo gas, rather than a Local Group medium. There are no compelling detections of the intergalactic hot gas (0.5-10E6 K) either in absorption or emission and these upper limits are consistent with theoretical models. Claimed X-ray absorption lines are not confirmed, while most of the claims of soft emission are attributable to artifacts of background subtraction and field-flattening. The missing baryons should become detectable with moderate improvements in instrumental sensitivity.Comment: To appear in Annual Review of Astronomy and Astrophysics, Vol 45 (Sept 2007) 44 pages, including 11 figure

The Effect of Dose Rate on the Survival of S3 HeLa Cells Exposed to Cobalt 60 Gamma Radiation

The investigation was designed to determine whether the rate at which a dose of ionizing radiation is delivered affects its ability to sterilize single cells grown in vitro. The cells were cultured using the techniques originally described by Puck and his co-workers, whereby mammalian cells may be treated as independent micro-organisms. This technique enables the description of a quantitative relationship between the dose delivered to a population of single cells and the fraction of the population “reproductively surviving,\u22 i.e. able to reproduce indefinitely. Doses of 100 to 1000 rads were delivered at dose—rates of 2.37, 16.9, and 44.9 rads per minute. At every dose level, 18 plates containing pre-irradiated feeder layers were inoculated with an equal number of S3 HeLa cells and divided into three sets of 6 plates. All three sets received the same total dose of cobalt 60 gamma radiation, but the first set received its dose at a rate of 2.37 rads per minute, the second, at 16.9 rads per minute, and the third at 44.9 rads per minute. These plates were then incubated for a period of about two weeks, after which they were fixed, stained and the number of colonies on each plate counted. In every case, it was found that the effectiveness of the radiation in sterilizing the cells was increased when the dose-rate was increased. The magnitude of the dose-rate effect at the cellular level was sufficient to account for published reports of variation in LD 50/30 for whole-body irradiated small mammals

Do more online instructional ratings lead to better prediction of instructor quality?

Online instructional ratings are taken by many with a grain of salt. This study analyzes the ability of said ratings to estimate the official (university-administered) instructional ratings of the same respective university instructors. Given self-selection among raters, we further test whether more online ratings of instructors lead to better prediction of official ratings in terms of both R-squared value and root mean squared error. We lastly test and correct for heteroskedastic error terms in the regression analysis to allow for the first robust estimations on the topic. Despite having a starkly different distribution of values, online ratings explain much of the variation in official ratings. This conclusion strengthens, and root mean squared error typically falls, as one considers regression subsets over which instructors have a larger number of online ratings. Though (public) online ratings do not mimic the results of (semi-private) official ratings, they provide a reliable source of information for predicting official ratings. There is strong evidence that this reliability increases in online rating usage. Accessed 6,372 times on https://pareonline.net from February 22, 2011 to December 31, 2019. For downloads from January 1, 2020 forward, please click on the PlumX Metrics link to the right

Harnessing post-translational modifications for next-generation HIV immunogens

The extensive post-translational modifications of the envelope spikes of the human immunodeficiency virus (HIV) present considerable challenges and opportunities for HIV vaccine design. These oligomeric glycoproteins typically have over 30 disulfide bonds and around a 100 N-linked glycosylation sites, and are functionally dependent on protease cleavage within the secretory system. The resulting mature structure adopts a compact fold with the vast majority of its surface obscured by a protective shield of glycans which can be targeted by broadly neutralizing antibodies (bnAbs). Despite the notorious heterogeneity of glycosylation, rare B-cell lineages can evolve to utilize and cope with viral glycan diversity, and these structures therefore present promising targets for vaccine design. The latest generation of recombinant envelope spike mimetics contains re-engineered post-translational modifications to present stable antigens to guide the development of bnAbs by vaccination

Sexualized and Dangerous Relationships: Listening to the Voices of Low-Income African American Girls Placed at Risk for Sexual Exploitation

Introduction: Youth from low-income, urban backgrounds face significant challenges to maintaining a positive developmental trajectory. Dangerous neighborhoods and stressed relationships are common in these settings and threaten adaptation by weakening the natural assets that undergird resilience. African American girls in these contexts face specific, multiple risks, including gender stereotyping, violence, and sexual exploitation. The commercial sexual exploitation of children (CSEC) is a multibillion-dollar industry victimizing over 1 million children around the globe.1 The typical victim in 1 city in the southeastern United States is an African American girl 12-14 years old. There has been little research investigating the characteristics of girls placed at risk for CSEC and even less research on the personal perspectives of these girls. Methods: Over 3 school terms we provided preventive intervention groups for 36 African American middle school girls who were placed at risk because they lived in neighborhoods with high rates of interpersonal violence and CSEC. Two group leaders and a process recorder took detailed notes on each group session. Our focus on group conversations over a period of weeks increased the probability of recording spontaneous, open comments by the children and is a promising method with this population. The data were analyzed qualitatively and resulted in an account of the girls’ own views of the environmental challenges and personal experiences that may influence their development. Results: The girls’ language during the group sessions contained 4 themes: difficulty forming trusting relationships, frequent peer aggression, familiarity with adult prostitution, and sexuality as a commodity. Conclusion: Our research shows how girls placed at risk for CSEC view their own lives. These children described violence and sexual exploitation and cited limited supports to protect them from these risks. Understanding the perspectives of these girls should generate future research and intervention strategies to support their coping and resilience