Quantum Sampling Problems, BosonSampling and Quantum Supremacy

There is a large body of evidence for the potential of greater computational power using information carriers that are quantum mechanical over those governed by the laws of classical mechanics. But the question of the exact nature of the power contributed by quantum mechanics remains only partially answered. Furthermore, there exists doubt over the practicality of achieving a large enough quantum computation that definitively demonstrates quantum supremacy. Recently the study of computational problems that produce samples from probability distributions has added to both our understanding of the power of quantum algorithms and lowered the requirements for demonstration of fast quantum algorithms. The proposed quantum sampling problems do not require a quantum computer capable of universal operations and also permit physically realistic errors in their operation. This is an encouraging step towards an experimental demonstration of quantum algorithmic supremacy. In this paper, we will review sampling problems and the arguments that have been used to deduce when sampling problems are hard for classical computers to simulate. Two classes of quantum sampling problems that demonstrate the supremacy of quantum algorithms are BosonSampling and IQP Sampling. We will present the details of these classes and recent experimental progress towards demonstrating quantum supremacy in BosonSampling.Comment: Survey paper first submitted for publication in October 2016. 10 pages, 4 figures, 1 tabl

The partially alternating ternary sum in an associative dialgebra

The alternating ternary sum in an associative algebra, $abc - acb - bac + bca + cab - cba$, gives rise to the partially alternating ternary sum in an associative dialgebra with products $\dashv$ and $\vdash$ by making the argument $a$ the center of each term: $a \dashv b \dashv c - a \dashv c \dashv b - b \vdash a \dashv c + c \vdash a \dashv b + b \vdash c \vdash a - c \vdash b \vdash a$. We use computer algebra to determine the polynomial identities in degree $\le 9$ satisfied by this new trilinear operation. In degrees 3 and 5 we obtain $[a,b,c] + [a,c,b] \equiv 0$ and $[a,[b,c,d],e] + [a,[c,b,d],e] \equiv 0$; these identities define a new variety of partially alternating ternary algebras. We show that there is a 49-dimensional space of multilinear identities in degree 7, and we find equivalent nonlinear identities. We use the representation theory of the symmetric group to show that there are no new identities in degree 9.Comment: 14 page

Men who have sex with men who do not access sexual health clinics nor disclose sexual orientation are unlikely to receive the HPV vaccine in the UK

Background: Men who have sex with men (MSM) are recommended the Human Papillomavirus (HPV) vaccination due to their higher risk of genital warts and anal cancer. Purpose: To examine HPV vaccine acceptability amongst MSM in the UK. Methods: Using advertisements via Facebook, MSM were recruited to an online survey measuring motivations for HPV vaccination. Logistic regression was performed to identify predictors of HPV vaccine acceptability. Results: Out of 1508 MSM (median age = 22, range: 14–63 years) only 19% had good knowledge of HPV. Overall, 55% of MSM were willing to ask for the HPV vaccine and 89% would accept it if offered by a healthcare professional (HCP). Access to sexual health clinics (SHCs) [OR = 1.82, 95% CI 1.29–2.89], the disclosure of sexual orientation to a HCP [OR = 2.02, CI 1.39–3.14] and HIV-positive status [OR = 1.96, CI 1.09–3.53] positively predicted HPV vaccine acceptability. After receiving information about HPV, perceptions of HPV risk [OR = 1.31, CI 1.05–1.63], HPV infection severity [OR = 1.89, CI 1.16–3.01), HPV vaccination benefits [OR = 1.61, CI 1.14–3.01], HPV vaccine effectiveness [OR = 1.54, CI 1.14–2.08], and the lack of perceived barriers to HPV vaccination [OR = 4.46, CI 2.95–6.73] were also associated with acceptability. Conclusions: Although nearly half of MSM would not actively pursue HPV vaccination, the vast majority would accept the vaccine if recommended by HCPs. In order to achieve optimal uptake, vaccine promotion campaigns should focus on MSM who do not access SHCs and those unwilling to disclose their sexual orientation

High Temperature Tribological Properties of Polybenzimidazole (PBI)

Polybenzimidazole (PBI) is a high performance polymer that can potentially replace metal components in some high temperature conditions where lubrication is challenging or impossible. Yet most characterisations so far have been conducted at relatively low temperatures. In this work, the tribological properties of PBI were examined with a steel ball-PBI disc contact at 280 °C under high load and high sliding speed conditions. The dry friction coefficient is relatively low and decreases modestly with increasing applied load. Surface analysis shows that PBI transfer layers are responsible for the low friction observed. In-situ contact temperature measurements were performed to provide for the first time direct links between the morphology and distribution of the transfer layer, and the temperature distribution in the contact. The results show that high pressure and high temperature in heavily loaded contacts promote the removal and the subsequent regeneration of a transfer layer, resulting in a very thin transfer layer on the steel counterface. FeOOH is formed in the contact at high loads, instead of Fe2O3. This may affect the adhesion between PBI and the counterface and thus influence the transfer layer formation process. To control PBI wear, contact temperature management will be crucial

Non-adaptive Measurement-based Quantum Computation and Multi-party Bell Inequalities

Quantum correlations exhibit behaviour that cannot be resolved with a local hidden variable picture of the world. In quantum information, they are also used as resources for information processing tasks, such as Measurement-based Quantum Computation (MQC). In MQC, universal quantum computation can be achieved via adaptive measurements on a suitable entangled resource state. In this paper, we look at a version of MQC in which we remove the adaptivity of measurements and aim to understand what computational abilities still remain in the resource. We show that there are explicit connections between this model of computation and the question of non-classicality in quantum correlations. We demonstrate this by focussing on deterministic computation of Boolean functions, in which natural generalisations of the Greenberger-Horne-Zeilinger (GHZ) paradox emerge; we then explore probabilistic computation, via which multipartite Bell Inequalities can be defined. We use this correspondence to define families of multi-party Bell inequalities, which we show to have a number of interesting contrasting properties.Comment: 13 pages, 4 figures, final version accepted for publicatio

Bell Inequalities with Auxiliary Communication

What is the communication cost of simulating the correlations produced by quantum theory? We generalize Bell inequalities to the setting of local realistic theories augmented by a fixed amount of classical communication. Suppose two parties choose one of M two-outcome measurements and exchange 1 bit of information. We present the complete set of inequalities for M = 2, and the complete set of inequalities for the joint correlation observable for M = 3. We find that correlations produced by quantum theory satisfy both of these sets of inequalities. One bit of communication is therefore sufficient to simulate quantum correlations in both of these scenarios.Comment: 5 page

A systematic review of air pollution and incidence of out-of-hospital cardiac arrest

Introduction: Studies have linked air pollution with the incidence of acute coronary artery events and cardiovascular mortality but the association with out-of-hospital cardiac arrest (OHCA) is less clear. Aim: To examine the association of air pollution with the occurrence of OHCA.Methods: Electronic bibliographic databases (until February 2013) were searched. Search terms included common air pollutants and OHCA. Studies of patients with implantable cardioverter defibrillators and OHCA not attended by paramedics were excluded. Two independent reviewers (THKT and TAW) identified potential studies. Methodological: quality was assessed by the Newcastle-Ottawa Scale.Results: Of 849 studies, 8 met the selection criteria. Significant associations between particulate matter (PM) exposure (especially PM2.5) and OHCA were found in 5 studies. An increase of OHCA risk ranged from 2.4% to 7% per interquartile increase in average PM exposure on the same day and up to 4 days prior to the event. A large study found ozone increased the risk of OHCA within 3 h prior to the event. The strongest risk OR of 3.8–4.6% per 20 parts per billion ozone increase of the average level was within 2 h prior to the event. Similarly, another study found an increased risk of 18% within 2 days prior to the event.Conclusions: Larger studies have suggested an increased risk of OHCA with air pollution exposure from PM 2.5 and ozone

Outcome Independence of Entanglement in One-Way Computation

We show that the various intermediate states appearing in the process of one-way computation at a given step of measurement are all equivalent modulo local unitary transformations. This implies, in particular, that all those intermediate states share the same entanglement irrespective of the measurement outcomes, indicating that the process of one-way computation is essentially unique with respect to local quantum operations.Comment: 6 pages, 4 figure

Release of ammonium and organic matter from soil by hydrofluoric acid and effect of hydrofluoric acid treatment on extraction of soil organic matter by neutral and alkaline reagents

RESP-408

Lie group weight multiplicities from conformal field theory

Dominant weight multiplicities of simple Lie groups are expressed in terms of the modular matrices of Wess-Zumino-Witten conformal field theories, and related objects. Symmetries of the modular matrices give rise to new relations among multiplicities. At least for some Lie groups, these new relations are strong enough to completely fix all multiplicities.Comment: 12 pages, Plain TeX, no figure