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Some aspects of the concepts of counterfactuality and probability are explored as they apply to the specific example of the famous “EPR-Bell” experiments realized by physicists over the last half-century. In particular the question is raised: what hypotheses about actually conducted experiments do the results exclude? It is argued that the answer depends on both whether these hypotheses are deterministic or stochastic, and on the “cardinality” of the experiment relative to the theory.

Abstract Most of the discussion in the literature of the Majorana fermions (M.F.’s) believed to exist in so-called 2D p + ip $\text{p}+\text{ip}$ Fermi superfluids, and in particular of their possible application in topological quantum computing (TQC) has analyzed the problem using the familiar Bogoliubov–de Gennes (mean-field) formalism, which conserves total electron number only mod 2. We raise the question: Suppose that we require that electron number be conserved, period, at all stages of the calculation, then what are the consequences for the characteristic properties of M.F.’s, in particular for their (physical) braiding statistics? While we do not provide a definitive answer to this question, our considerations suggest that these consequences could be enough to destroy the possibility of using these excitations for TQC, and certainly indicate that the problem deserves further study.

Amidoxime-functionalized polymeric adsorbents are the most promising materials for harvesting uranium from seawater. Here the authors investigate the preferential extraction of vanadium over uranium by polyamidoximes by exploring the unusually strong and selective binding of vanadium.

Photosynthesis uses only a limited range of solar radiation. Here, Graysonet al. genetically incorporated the yellow fluorescent protein (YFP) chromophore into a bacterial photosystem, and show that energy harvested by reaction centre–YFP complexes can augment photosynthesis in vivo.

Objective collapse theories are formulations of quantum physics that attempt to solve the measurement problem through modified dynamical laws. Here, the authors constrain such theories by testing a generalization of the Leggett-Garg inequality in a superconducting flux qubit experiment.

We performed an experimental study of the temperature and doping dependence of the energy-loss function of the bilayer and trilayer bismuth cuprates family. The primary aim is to obtain information on the energy stored in the Coulomb interaction between the conduction electrons, on the temperature dependence thereof, and on the change of Coulomb interaction when Cooper pairs are formed. We performed temperature-dependent ellipsometry measurements on several Bi_{2}Sr_{2}CaCu_{2}O_{8-x} single crystals: underdoped with T_{c}=60, 70, and 83 K; optimally doped with T_{c}=91 K; overdoped with T_{c}=84, 81, 70, and 58 K; as well as optimally doped Bi_{2}Sr_{2}Ca_{2}Cu_{3}O_{10+x} with T_{c}=110 K. Our first observation is that, as the temperature drops through T_{c}, the loss function in the range up to 2 eV displays a change of temperature dependence as compared to the temperature dependence in the normal state. This effect at—or close to—T_{c} depends strongly on doping, with a sign change for weak overdoping. The size of the observed change in Coulomb energy, using an extrapolation with reasonable assumptions about its q dependence, is about the same size as the condensation energy that has been measured in these compounds. Our results therefore lend support to the notion that the Coulomb energy is an important factor for stabilizing the superconducting phase. Because of the restriction to small momentum, our observations do not exclude a possible significant contribution to the condensation energy of the Coulomb energy associated with the region of q around (π,π).