CMT Forum: Ananda Roy

For over half a century, lattice spin systems have been the gold-standard for simulation of non-perturbative properties of quantum field theories (QFTs). Departing from this well-established paradigm, here I present lattice models constructed using Josephson junction arrays that realize strongly interacting QFTs in the scaling limit. As an example, I will describe a perturbed quantum sine-Gordon model that exhibits ‘quark confinement’ and ‘false-vacuum decay’. The corresponding lattice model is realized using ordinary Josephson junctions and 0−𝜋 qubits. Subsequently, I will present a lattice realization of a topological interface between two free boson conformal field theories. The latter can be realized by coupling special one-dimensional superconductors. The gapless excitations in the latter carry charges that are specific integer multiples of the charge of Cooper-pairs. These integers determine the windings in the target space of the bosonic fields – a crucial element required to give rise to nontrivial topological interfaces. The scaling limit is reached faster for the Josephson-junction-based lattice models compared to spin chains, enabling quantitative investigation of several QFTs which have so far eluded ab-initio analysis.

References:

1) Ananda Roy and Sergei Lukyanov, Nat. Comm. 14, 7433 (2023)
2) Ananda Roy and Hubert Saleur, Phys. Rev. B 109, L161107 (2024)