Experimental evidence of a ϕ Josephson junction

Abstract

We demonstrate experimentally the existence of Josephson junctions having a doubly degenerate ground state with an average Josephson phase ψ=\pmϕ. The value of ϕ can be chosen by design in the interval 0<ϕ<π. The junctions used in our experiments are fabricated as 0-π Josephson junctions of moderate normalized length with asymmetric 0 and π regions. We show that (a) these ϕ Josephson junctions have two critical currents, corresponding to the escape of the phase ψ from -ϕ and +ϕ states; (b) the phase ψ can be set to a particular state by tuning an external magnetic field or (c) by using a proper bias current sweep sequence. The experimental observations are in agreement with previous theoretical predictions.

References in corpus (8)

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• φ-State and Inverted Fraunhofer Pattern in Nonaligned Josephson Junctions
• Josephson junction ratchet: effects of finite capacitances
• Phase diagram of Josephson junction between s and s+- superconductors in dirty limit
• Tunable $\phi$ Josephson Junction ratchet
• Josephson response of a conventional and a noncentrosymmetric superconductor coupled via a double quantum dot
• Electrically modulated SQUID with single Josephson junction coupled by a time-reversal breaking Weyl semimetal thin film
• Bistable state in superconductor/ferromagnet heterostructures
• Spontaneous vortex state and $\phi$-junction in a superconducting bijunction with a localized spin
• Tunable ground states in helical $p$-wave Josephson junctions