Dynamical Superconducting Parity Effect in a Coulomb Pb Island

Area of Science:

• Condensed matter physics
• Quantum phenomena
• Nanotechnology

Background:

• Single-electron tunneling in superconducting islands exhibits parity-modulated Coulomb blockade.
• The quasiparticle dynamics governing Cooper-pair condensate coherence and charging energy are not fully understood.

Purpose of the Study:

• To investigate a novel superconducting parity effect in Coulomb blockade systems.
• To understand the role of quasiparticle dynamics in Cooper-pair condensation and transport.

Main Methods:

• Low-temperature scanning tunneling spectroscopy on nano-sized lead (Pb) islands.
• Spectroscopic measurements to analyze Coulomb gaps and peak distributions.
• Validation through parity transition of a Coulomb charge ring.
• Theoretical simulations to corroborate experimental findings.

Main Results:

• Discovery of a distinct parity-dependent Coulomb gap near the Fermi energy.
• Observation of equidistant Coulomb peaks at higher energies.
• Identification of a new parity effect, different from conventional even-odd alternations.
• Evidence for an emergent tunneling channel via electron-hole conversion dynamically coupled to Cooper-pair condensation.

Conclusions:

• The study reveals a "dynamical" superconducting parity effect in mesoscopic superconducting islands.
• This effect originates from quasiparticle-mediated electron-hole conversion processes.
• Findings highlight the crucial role of quasiparticles in Cooper-pair formation within Coulomb blockade transport.