Determine the origin of finite-gap strong-drive Shapiro-amplitude discrepancies

Determine whether the qualitative finite-gap strong-drive locking-amplitude discrepancies can be eliminated within the Lindblad bath class through improved reference states or dissipator structures, or whether they reflect a deeper difference between real-time relaxation and the frequency-domain periodic steady state in a dissipation-free coherent channel.

Background

The paper demonstrates Shapiro locking in finite-gap superconducting quantum-dot junctions, including integer and fractional resonances and their selection rules. However, the absolute locking amplitudes differ substantially from the Floquet frequency-domain benchmark, with the discrepancy attributed to the dissipation-free coherent subgap channel and therefore treated as qualitative rather than quantitatively resolved.

The authors identify two unresolved possibilities: improving the reference state or dissipator structure within the Lindblad bath framework may close the discrepancy, or the discrepancy may reflect a more fundamental difference between real-time relaxation and the frequency-domain periodic steady state. They explicitly state that this issue remains under investigation.