Spatial interference changes the symmetry class of a Josephson element

Abstract:Spatial interference can break the inversion symmetry of an effective Josephson potential even in a laterally homogeneous junction with inversion-symmetric local energy. We derive a general criterion based on harmonic-dependent complex spatial form factors: a single local harmonic remains a shifted cosine, whereas multiple harmonics can acquire phases incompatible with any common inversion center, permitting cubic interactions and three-wave mixing. Phase reflection reverses all odd-order expansion coefficients about corresponding minima while preserving the even-order ones. For a capacitively shunted junction at fixed charging energy and arbitrary offset charge, it also preserves the complete quantum spectrum, enabling reversal of the odd nonlinear sector without spectral retuning. A centered cross junction with multiple local harmonics is one concrete example. Within the imposed-field model, a three-component magnetic field can generate an inversion-asymmetric effective potential, and reversing an odd number of field components exactly reflects it without changing the quantum spectrum of the capacitively shunted junction.

Superconductivity (cond-mat.supr-con); Quantum Physics (quant-ph)

arXiv:2610.15746 [cond-mat.supr-con]

(or arXiv:2610.15746v1 [cond-mat.supr-con] for this version)

https://doi.org/10.48550/arXiv.2610.15746 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website.

Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them.

Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs.