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Résumé |
What are the laws describing small circuits assembled from several quantum components? Here we address
experimentally the elementary case of a ballistic circuit with a single node, realized by a micron-scale metallic
island connected only by perfect electronic quantum channels. In this regime, the electrical conductance is
simply given by the classical composition of one electrical conductance quantum per channel. However, we
observe that a single quantum channel is universally suppressed for the flow of heat, in violation of the
widespread Wiedemann-Franz relation between thermal and electrical conductances. This results from the
suppression of the fluctuations of the island’s charge at low temperature. In the limit case of a single channel,
theory not only predicts a full heat blockade, but that no information can be transferred from the many
quasiparticles inside the metallic island through the electrically connected channel. A striking consequence is
that the quantum state of each electron penetrating inside the island is imprinted into the quantum state of
another, indiscernible electron simultaneously emitted. Such a form of electron teleportation is established
between well-separated injection and emission locations, through two-path interferences in the integer
quantum Hall regime. |
