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 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 γ26% 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_-∈Δφπ, possibly relevant for future superconducting electronics.