Catalytic quantum teleportation

Quantum catalysis is an intricate feature of quantum entanglement. It demonstrates that in certain situations the very presence of entanglement can improve one's abilities of manipulating other entangled states. At the same time, however, it is not clear if using entanglement catalytically can provide additional power for any of the existing quantum protocols. Here we show, for the first time, that catalysis of entanglement can provide a genuine advantage in the task of quantum teleportation. More specifically, we show that extending the standard teleportation protocol by giving Alice and Bob the ability to use entanglement catalytically, allows them to achieve fidelity of teleportation at least as large as the regularisation of the standard teleportation quantifier, the so-called average fidelity of teleportation. Consequently, we show that this regularised quantifier surpasses the standard benchmark for a variety of quantum states, therefore demonstrating that there are quantum states whose ability to teleport can be further improved when assisted with entanglement in a catalytic way. This hints that entanglement catalysis can be a promising new avenue for exploring novel advantages in the quantum domain.Comment: 6 + 2 pages, 2 figures. Comments welcome

Determination of Strange Sea Quark Distributions from Fixed-target and Collider Data

We present an improved determination of the strange sea distribution in the nucleon with constraints coming from the recent charm production data in neutrino-nucleon deep-inelastic scattering by the NOMAD and CHORUS experiments and from charged current inclusive deep-inelastic scattering at HERA. We demonstrate that the results are consistent with the data from the ATLAS and the CMS experiments on the associated production of $W^\pm$-bosons with $c$-quarks. We also discuss issues related to the recent strange sea determination by the ATLAS experiment using LHC collider data.Comment: 23 pages, 14 figure

Multiobject operational tasks for convex quantum resource theories of state-measurement pairs

The prevalent modus operandi within the framework of quantum resource theories has been to characterise and harness the resources within single objects, in what we can call \emph{single-object} quantum resource theories. One can wonder however, whether the resources contained within multiple different types of objects, now in a \emph{multi-object} quantum resource theory, can simultaneously be exploited for the benefit of an operational task. In this work, we introduce examples of such multi-object operational tasks in the form of subchannel discrimination and subchannel exclusion games, in which the player harnesses the resources contained within a state-measurement pair. We prove that for any state-measurement pair in which either of them is resourceful, there exist discrimination and exclusion games for which such a pair outperforms any possible free state-measurement pair. These results hold for arbitrary convex resources of states, and arbitrary convex resources of measurements for which classical post-processing is a free operation. Furthermore, we prove that the advantage in these multi-object operational tasks is determined, in a multiplicative manner, by the resource quantifiers of: \emph{generalised robustness of resource} of both state and measurement for discrimination games and \emph{weight of resource} of both state and measurement for exclusion games.Comment: 5+8 page