École Polytechnique Lab Probes Fermion Parity with Josephson Effect

Researchers at École Polytechnique, CNRS have demonstrated a new method for detecting fermion parity, a fundamental property of superconductivity, by utilizing a carbon nanotube-based Andreev molecule. The work employs two coupled quantum-dot Josephson junctions to observe the formation of delocalized Andreev molecular states extending across both junctions, a key step in controlling these complex systems. Changes in the molecular ground-state parity manifest as characteristic phase shifts in the nonlocal response, identifying global fermion parity as an experimentally accessible degree of freedom. This approach could prove relevant for devices designed to encode quantum information…