Understanding the functions of a brain region requires knowing the neural
representations of its myriad inputs, local neurons, and outputs. Primary visual
cortex (V1) has long been thought to compute visual orientation from untuned
thalamic inputs, but very few thalamic inputs have been measured in any mammal.
We determined the response properties of ~28,000 thalamic boutons and
~4,000 cortical neurons in layers 1–5 of awake mouse V1. With
adaptive optics allowing accurate measurement of bouton activity deep in cortex,
we found that around half of the boutons in the main thalamorecipient L4 carry
orientation-tuned information, and their orientation/direction biases are also
dominant in the L4 neuron population, suggesting that these neurons may inherit
their selectivity from tuned thalamic inputs. Cortical neurons in all layers
exhibited sharper tuning than thalamic boutons and a greater diversity of
preferred orientations. Our results provide data-rich constraints for refining
mechanistic models of cortical computation.
Split Cooper pair is a natural source for entangled electrons which is a basic ingredient for quantum information in solid state. We report an experiment on a superconductor-graphene double quantum dot (QD) system, in which we observe Cooper pair splitting (CPS) up to a CPS efficiency of ∼ 10%. With bias on both QDs, we are able to detect a positive conductance correlation across the two distinctly decoupled QDs. Furthermore, with bias only on one QD, CPS and elastic co-tunneling can be distinguished by tuning the energy levels of the QDs to be asymmetric or symmetric with respect to the Fermi level in the superconductor.
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