Quantum Circuits with Multiterminal Josephson-Andreev Junctions

Quantum Circuits with Multiterminal Josephson-Andreev Junctions - Featured

One strategy to mitigate the effects of the environmental noise on qubits is to design their hardware with intrinsic immunity against it. In this work, a novel platform is proposed to obtain that kind of protection by using multiterminal Josephson junctions, which are like meeting points for several superconducting electrodes. While other protected implementations use superconducting circuits with a few conventional two-terminal Josephson junctions, this requires just one — but multiterminal. Multiterminal devices can be fabricated using present-day techniques that combine superconductors with semiconductors, thus allowing for additional tunability. In this case, the resulting mesoscopic junctions are fundamentally different than their purely metallic counterparts, for their own fermionic excitations hybridize with the circuit bosonic modes. This fermionic-bosonic coupling plays a central role, which connects with the field of strong light-matter interaction. Moreover, the models for these systems evoke a compelling analogy with a crystal: they can be mapped into a lattice with as many dimensions as circuit bosonic modes and a polyatomic unit cell describing the fermionic sector, providing direct insight into the properties of the multiterminal junctions in different circuit configurations. [Full article]

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