Fabry-Perot superconducting diode

Superconducting diode effects (SDEs) occur in systems with asymmetric critical supercurrents |I+c|≠|I-c| yielding dissipationless flow in one direction (e.g., +), while dissipative transport in the opposite direction (-). Here we investigate the SDE in a phase-biased φ Josephson junction with a double-barrier resonant-tunneling InAs nanowire nested between proximitized InAs/Al leads with finite momentum h q Cooper pairing. Within the Bogoliubov-de Gennes (BdG) approach, we obtain the exact BCS ground state energy EG(q,φ) and I+c≠|I-c| from the current-phase relation IG(q,φ)∼∂φEG(q,φ). The SDE arises from the accrued Andreev phase shifts δφL,R(q,φ) leading to asymmetric BdG spectra for q≠0. Remarkably, the diode efficiency γ=(I+c-|I-c|)/(I+c+|I-c|) shows multiple Fabry-Perot resonances γ≃26% at the double-barrier Andreev bound states as the well depth Vg is varied. Our γ also features sign reversals for increasing q and high sensitiveness to fermion-parity transitions. The latter enables I+c(φ+)↔I-c(φ-) switchings over narrow phase windows, i.e., φ+,φ- Δφχπ, possibly relevant for future superconducting electronics.