No abstract

prospects of proposals such as quantum-interferometric optical lithography. The method can be adapted to generate entangled states of arbitrarily large photon number. Because prior entanglement is not required, the procedure would work well with singlephoton-on-demand sources 29,30 , which promise to be more efficient and scalable than down-conversion sources. Scalability would also be enhanced by the use of photon-number-resolving detectors. The construction proceeds from spatially separated, unentangled photons to a maximally entangled state in a single spatial mode, a state suitable for Heisenberg-limited phase measurements.A

No abstract

No abstract

Surface temperature is a fundamental parameter of Earth's climate. Its evolution through time is commonly reconstructed using the oxygen isotope and the clumped isotope compositions of carbonate archives. However, reaction kinetics involved in the precipitation of carbonates can introduce inaccuracies in the derived temperatures. Here, we show that dual clumped isotope analyses, i.e., simultaneous Δ 47 and Δ 48 measurements on the single carbonate phase, can identify the origin and quantify the extent of these kinetic biases. Our results verify theoretical predictions and evidence that the isotopic disequilibrium commonly observed in speleothems and scleractinian coral skeletons is inherited from the dissolved inorganic carbon pool of their parent solutions. Further, we show that dual clumped isotope thermometry can achieve reliable palaeotemperature reconstructions, devoid of kinetic bias. Analysis of a belemnite rostrum implies that it precipitated near isotopic equilibrium and confirms the warmer-than-present temperatures during the Early Cretaceous at southern high latitudes.

No abstract

No abstract

No abstract