Universal quantum gates between nitrogen-vacancy centers in a levitated nanodiamond

We propose a scheme to realize universal quantum gates between nitrogen-vacancy (NV) centers in an optically trapped nanodiamond, through uniform magnetic field induced coupling between the NV centers and the torsional mode of the levitated nanodiamond. The gates are tolerant to the thermal noise of the torsional mode. By combining the scheme with dynamical decoupling technology, it is found that the high fidelity quantum gates are possible for the present experimental conditions. The proposed scheme is useful for NV-center-based quantum network and distributed quantum computationComment: 7 pages, 6 figure

Motivations and Barriers Associated with the Adoption of Battery Electric Vehicles in Beijing: A Multinomial Logit Model Approach

The recent surge of the Chinese Plug-in Hybrid Electric Vehicle (PEV) market makes China the world’s largest PEV stock. A series of supportive policies in China contributed greatly to the rapid PEV adoption by limiting regular vehicles and reducing the price of PEVs. However, the role these policies play in changing references and encouraging consumers to purchase PEVs rather than conventional vehicles is not fully known. Other factors, rather than incentives, that could help maintain the current adoption trend are still unclear. The latter is especially critical in understanding how the market reacts to a gradually decreasing level of incentives to achieve the next goal of 5 million PEVs on the road by 2020 in China. Therefore, in this study the authors explored these research questions through a cross-sectional study of the current PEV market on consumers in Beijing by employing a multinomial logit model. Beijing has high levels of PEV adoptions in addition to a specific policy stimulus. The model results show significant influences of stimuli, individual socio-demographics, attitudes, charging infrastructure, and charging experiences on the adoption of PEVs over conventional vehicles. The results may help find out key interventions for policy makers to promote more PEV adoptions in China as well as other countries

Factorization Violation and Scale Invariance

Factorization violating effects in hadron scattering are due mainly to spectator-spectator interactions. While it is known that these interactions cancel in inclusive cross sections, like for the Drell-Yan process, not much is known about for what classes of observables factorization is violated. We show that for pure Glauber ladder graphs, all amplitude-level factorization violating effects completely cancel at cross section level for any single-scale observable (such as hadronic transverse energy or beam thrust). This result disproves previous claims that these pure Glauber graphs are factorization-violating. Our proof exploits scale invariance of two-to-two scattering amplitudes in an essential way. The leading factorization-violating effects therefore come from graphs with at least one soft gluon, involving the Lipatov vertex off of the Glauber ladders. This implies that real soft radiation must be involved in factorization-violation, shedding light on the connection between factorization-violation and the underlying event.Comment: 36 pages, 15 figure

Collinear factorization violation and effective field theory

The factorization of amplitudes into hard, soft and collinear parts is known to be violated in situations where incoming particles are collinear to outgoing ones. This result was first derived by studying limits where non-collinear particles become collinear. We show that through an effective field theory framework with Glauber operators, these factorization-violating effects can be reproduced from an amplitude that is factorized before the splitting occurs. We confirm results at one-loop, through single Glauber exchange, and at two-loops, through double Glauber exchange. To approach the calculation, we begin by reviewing the importance of Glauber scaling for factorization. We show that for any situation where initial state and final state particles are not collinear, the Glauber contribution is entirely contained in the soft contribution. The contributions coming from Glauber operators are necessarily non-analytic functions of external momentum, with the non-analyticity arising from the rapidity regulator. The non-analyticity is critical so that Glauber operators can both preserve factorization when it holds and produce factorization-violating effects when they are present.Comment: 55 Pages, 5 figure