Within 11-dimensional supergravity we compute the logarithmic correction to the entropy of magnetically charged asymptotically AdS_{4} black holes with arbitrary horizon topology. We find perfect agreement with the expected microscopic result arising from the dual field theory computation of the topologically twisted index. Our result relies crucially on a particular limit to the extremal black hole case and clarifies some aspects of quantum corrections in asymptotically AdS spacetimes.

The topologically twisted index for ABJM theory with gauge group U(N ) k × U(N ) −k has recently been shown, in the large-N limit, to reproduce the BekensteinHawking entropy of certain magnetically charged asymptotically AdS 4 black holes. We numerically study the index beyond the large-N limit and provide evidence that it contains a subleading logarithmic term of the form −1/2 log N . On the holographic side, this term naturally arises from a one-loop computation. However, we find that the contribution coming from the near horizon states does not reproduce the field theory answer. We give some possible reasons for this apparent discrepancy.

We provide a field theory interpretation of the attractor mechanism for asymptotically AdS 4 dyonic BPS black holes whose entropy is captured by the supersymmetric index of the twisted ABJM theory at Chern-Simons level one. We holographically compute the renormalized off-shell quantum effective action in the twisted ABJM theory as a function of the supersymmetric fermion masses and the arbitrary vacuum expectation values of the dimension one scalar bilinear operators and show that extremizing the effective action with respect to the vacuum expectation values of the dimension one scalar bilinears is equivalent to the attractor mechanism in the bulk. In fact, we show that the holographic quantum effective action coincides with the entropy functional and, therefore, its value at the extremum reproduces the black hole entropy.

A bifunctional luminomagnetic ≈30 nm Gd1‐xEuxVO4 nanophosphor is synthesized using a facile sol–gel method. The nanophosphor is observed to produce both paramagnetic behavior and a highly efficient red emission peaking at 618 nm. Probing the luminomagnetic nanophosphor using photoluminescence, time‐resolved spectroscopy, magnetization measurements, and a cytotoxicity assay reveal its suitability for biological applications, in particular, cell labeling and high‐contrast imaging.

Using ζ-function regularization, we study the one-loop effective action of fundamental strings in AdS 5 ×S 5 dual to the latitude 1 4 -BPS Wilson loop in N = 4 Super-Yang-Mills theory. To avoid certain ambiguities inherent to string theory on curved backgrounds we subtract the effective action of the holographic 1 2 -BPS Wilson loop. We find agreement with the expected field theory result at first order in the small latitude angle expansion but discrepancies at higher order.