Frustration of decoherence in $Y$-shaped superconducting Josephson networks

Abstract

We examine the possibility that pertinent impurities in a condensed matter system may help in designing quantum devices with enhanced coherent behaviors. For this purpose, we analyze a field theory model describing Y- shaped superconducting Josephson networks. We show that a new finite coupling stable infrared fixed point emerges in its phase diagram; we then explicitly evidence that, when engineered to operate near by this new fixed point, Y-shaped networks support two-level quantum systems, for which the entanglement with the environment is frustrated. We briefly address the potential relevance of this result for engineering finite-size superconducting devices with enhanced quantum coherence. Our approach uses boundary conformal field theory since it naturally allows for a field-theoretical treatment of the phase slips (instantons), describing the quantum tunneling between degenerate levels.

11 pages, 5 .eps figures; several changes in the presentation and in the figures, upgraded references

References in corpus (6)

• Dynamics of one-dimensional Bose liquids: Andreev-like reflection at Y-junctions and absence of the Aharonov-Bohm effect
• Junctions of three quantum wires for spin 1/2 electrons
• Quantum Magnetic Impurities in Magnetically Ordered Systems
• Frustration of Decoherence in Open Quantum Systems
• Dissipative quantum oscillator with two competing heat baths
• Boundary Field Theory Approach to the Renormalization of SQUID Devices

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