Condensed Matter Seminar Series |
Frédéric Pierre
Université Paris-Saclay
From heat Coulomb blockade to electron state transmission
The combination of quantum mechanics and Coulomb interaction can result in profoundly different charge and heat propagation in small, nanoscale circuits. In this seminar I will present two such phenomena, seemingly very different but deeply connected through the fundamental relation between heat, entropy and information.
I will first show that heat flows differently. In violation of the classical Wiedemann-Franz law relating thermal and electrical conductions, a Coulomb induced blockade can apply selectively to the heat evacuation from a small metallic island. With ballistic channels, the electrical current flows freely but precisely one electronic channel is systematically suppressed for the flow of heat.
Second, I will demonstrate that the quantum state of electrons impinging on such a metallic island can be transmitted across it, a few microns away, with a high fidelity. For this purpose, we performed a two-path interferometry experiment where the original electrons recombine with indistinguishable electrons onto which the original electrons’ state has been imprinted. Such high-fidelity transmission is only possible if no information regarding the quantum state is transferred toward (measured by) the many electrons inside the island. In agreement with Shannon’s connection between heat and information transfers, we find that the electron quantum state transmission only takes place in a situation of complete heat Coulomb blockade, when a single channel is connected to the island.
Fig.: E-beam micrograph of an electronic Mach-Zehnder interferometer employed to test the fidelity of the non-local quantum state transmission of electrons across a metallic island (visually represented by a red dashed line).
[1] ‘Heat Coulomb blockade of one ballistic channel’. E. Sivre et al., Nat. Phys. 14, 145 (2018).
[2] ‘Transmitting the quantum state of electrons across a metallic island with Coulomb interaction’. H. Duprez et al., Science 366, 1243 (2019).
Zoom link: https://ucph-ku.zoom.us/j/6629
Zoom password: NielsBohr