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The strong light–matter coupling regime, in which excitations of materials hybridize with excitations of confined light modes into polaritons, holds great promise in various areas of science and technology. A key aspect for all applications of polaritonic chemistry is the relaxation into the lower polaritonic states. Polariton relaxation is speculated to involve two separate processes: vibrationally assisted scattering (VAS) and radiative pumping (RP), but the driving forces underlying these two mechanisms are not fully understood. To provide mechanistic insights, we performed multiscale molecular dynamics simulations of tetracene molecules strongly coupled to the confined light modes of an optical cavity. The results suggest that both mechanisms are driven by the same molecular vibrations that induce relaxation through nonadiabatic coupling between dark states and polaritonic states. Identifying these vibrational modes provides a rationale for enhanced relaxation into the lower polariton when the cavity detuning is resonant with specific vibrational transitions. peerReviewed

Kasvava uusiutuvan energian tarve ajaa tiedeyhteisöä etsimään uusia vihreitä energian lähteitä. Osana tätä tavoitetta, WISC-projekti pyrkii yhdistämään infrapunaa keräävän aurinkopaneelin normaaliin ikkunaan. Tässä tutkimuksessa me tutkimme sisääntulevan valon kytkeytymistä kallistuneesta kultananokartiosta laattamaisen aaltojohteen ohjattuihin aaltojohdemoodeihin; tavoitteena on esittää epäsymmetristä aaltojohteeseen kytkeytymistä. Tutkimus suoritettiin simuloimalla Comsolissa käyttäen kolmiulotteista äärellisten elementtien menetelmää. Ulospäin suuntautuva aaltojohteeseen sironneen valon energiavuo mitattiin 2.1 aallonpituuden päässä nanokartiosta. Tulokset viittaavat kahden samanaikaisen dipolaarisen plasmoniresonanssin olemassaoloon nanokartion sisällä ja että ne kykenevät sirottamaan valoa epäsymmetrisesti aaltojohdemoodeihin kapealla aallonpituuksien ja taittokulmien kaistaleella. Havaittu parhain mahdollinen tilanne viittaa siihen, että nanokartio kykenee sirottamaan valoa kallistusksen mukaiseen suuntaan 8.5 kertaa enemmän kuin kallistuken vastaiseen suuntaan. Nanopartikkelin muotoa ja kokoa voisi vielä optimoida pidemmälle jotta kahden dipolin välinen spektrien päällekkäisyys paranisi, mahdollisesti johtaen suurempaan epäsymmetriaan valon kytkennässä. Tulokset ovat tärkeä askel WISC-ikkunan takaisinsironnan minimoimisessa. The increasing global need for green energy drives the science community to find new green energy sources. As a part of that effort, the WISC-project aims to integrate an infrared-collecting solar panel into a normal window. In this study, we investigated the coupling of incident light into the guided modes of a slab waveguide by scattering from a tilted gold nanocone, with the goal of demonstrating asymmetric waveguide coupling. The study was done using three-dimensional finite element method simulations in Comsol. The outward energy flow of the scattered incident light into the waveguide modes was measured at a distance of 2.1 wavelengths from the nanocone. The results indicate the existence of two simultaneous dipolar particle plasmon resonances within the nanocone, and that they are capable of scattering light asymmetrically into the waveguide modes for a narrow range of wavelengths and particle tilt angles. The discovered best case scenario indicated that the nanocone can couple scattered light into the tilt direction 8.5 times more than into the opposing direction. The nanoparticle shape and size could be further optimized to achieve a better spectral overlap for the two dipoles, possibly leading to even higher coupling asymmetry. The results are an important step towards minimizing the back-scattering in a WISC-window.

Strassen's classical martingale coupling theorem states that two real-valued random variables are ordered in the convex (resp.\ increasing convex) stochastic order if and only if they admit a martingale (resp.\ submartingale) coupling. By analyzing topological properties of spaces of probability measures equipped with a Wasserstein metric and applying a measurable selection theorem, we prove a conditional version of this result for real-valued random variables conditioned on a random element taking values in a general measurable space. We also provide an analogue of the conditional martingale coupling theorem in the language of probability kernels and illustrate how this result can be applied in the analysis of pseudo-marginal Markov chain Monte Carlo algorithms. We also illustrate how our results imply the existence of a measurable minimiser in the context of martingale optimal transport., 21 pages

The currently available computational methods for the calculation of magnetic coupling constants with density functional theory have been reviewed. These methods include modern approximations to the exchangecorrelation functional, such as hybrid, range-separated and double-hybrid functionals, as well as approaches to treat the severe spin symmetry problems encountered in density functional calculations of magnetic interactions. In addition to the commonly used unrestricted Kohn–Sham formalism, density functional methods based on multireference wave functions and ensemble densities are also discussed. Performance of these models based on various studies has been summarized. The results indicate that self-interaction error plays an important role in the performance of density functional methods and is responsible for many of their shortcomings. If the self-interaction error and problems related to spin symmetry are treated in a theoretically correct manner, density functional theory can offer a very good description of magnetic coupling constants.

Contextuality is usually defined as absence of a joint distribution for a set of measurements (random variables) with known joint distributions of some of its subsets. However, if these subsets of measurements are not disjoint, contextuality is mathematically impossible even if one generally allows (as one must) for random variables not to be jointly distributed. To avoid contradictions one has to adopt the Contextuality-by-Default approach: measurements made in different contexts are always distinct and stochastically unrelated to each other. Contextuality is reformulated then in terms of the (im)possibility of imposing on all the measurements in a system a joint distribution of a particular kind: such that any measurements of one and the same property made in different contexts satisfy a specified property, $\mathcal{C}$. In the traditional analysis of contextuality $\mathcal{C}$ means "are equal to each other with probability 1". However, if the system of measurements violates the "no-disturbance principle", due to signaling or experimental biases, then the meaning of $\mathcal{C}$ has to be generalized, and the proposed generalization is "are equal to each other with maximal possible probability" (applied to any set of measurements of one and the same property). This approach is illustrated on arbitrary systems of binary measurements, including most of quantum systems of traditional interest in contextuality studies (irrespective of whether "no-disturbance" principle holds in them)., To be published in Fortschritte der Physik - Progress of Physics. The last version corrects a typo

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