Nuclear fusion in the deuterated cores of inflated hot Jupiters

Ouyed et al. (1998) proposed Deuterium (DD) fusion at the core-mantle interface of giant planets as a mechanism to explain their observed heat excess. But rather high interior temperatures (~10^5 K) and a stratified D layer are needed, making such a scenario unlikely. In this paper, we re-examine DD fusion, with the addition of screening effects pertinent to a deuterated core containing ice and some heavy elements. This alleviates the extreme temperature constraint and removes the requirement of a stratified D layer. As an application, we propose that, if their core temperatures are a few times 10^4 K and core composition is chemically inhomogeneous, the observed inflated size of some giant exoplanets (hot Jupiters) may be linked to screened DD fusion occurring deep in the interior. Application of an analytic evolution model suggests that the amount of inflation from this effect can be important if there is sufficient rock-ice in the core, making DD fusion an effective extra internal energy source for radius inflation. The mechanism of screened DD fusion, operating in the above temperature range, is generally consistent with the trend in radius anomaly with planetary equilibrium temperature $T_{rm eq}$, and also depends on planetary mass. Although we do not consider the effect of incident stellar flux, we expect that a minimum level of irradiation is necessary to trigger core erosion and subsequent DD fusion inside the planet. Since DD fusion is quite sensitive to the screening potential inferred from laboratory experiments, observations of inflated hot Jupiters may help constrain screening effects in the cores of giant planets.

Cold dark matter heats up

One of the principal discoveries in modern cosmology is that standard model particles (including baryons, leptons and photons) together comprise only 5% of the mass-energy budget of the Universe. The remaining 95% consists of dark energy and dark matter (DM). Consequently our picture of the universe is known as {Lambda}CDM, with {Lambda} denoting dark energy and CDM cold dark matter. {Lambda}CDM is being challenged by its apparent inability to explain the low density of DM measured at the centre of cosmological systems, ranging from faint dwarf galaxies to massive clusters containing tens of galaxies the size of the Milky Way. But before making conclusions one should carefully include the effect of gas and stars, which were historically seen as merely a passive component during the assembly of galaxies. We now understand that these can in fact significantly alter the DM component, through a coupling based on rapid gravitational potential fluctuations.

Symmetry constraints on temporal order in measurement-based quantum computation

We discuss the interdependence of resource state, measurement setting and temporal order in measurement-based quantum computation. The possible temporal orders of measurement events are constrained by the principle that the randomness inherent in quantum measurement should not affect the outcome of the computation. We provide a classification for all temporal relations among measurement events compatible with a given initial stabilizer state and measurement setting, in terms of a matroid. Conversely, we show that classical processing relations necessary for turning the local measurement outcomes into computational output determine the resource state and measurement setting up to local equivalence. Further, we find a symmetry transformation related to local complementation that leaves the temporal relations invariant.