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TT: Fachverband Tiefe Temperaturen

TT 30: Focus Session: Exploring Quantum Entanglement with Superconducting Qubits and Resonators (joint session QI/TT)

TT 30.11: Talk

Tuesday, March 19, 2024, 13:15–13:30, HFT-FT 131

Frustrated 2D-Josephson junction arrays with topological constraints — •Oliver Neyenhuys, Mikhail V. Fistul, and Ilya M. Eremin — Theoretische Physik III, Ruhr-Universität Bochum, Bochum 44801, Germany

Geometrical frustration in correlated systems can give rise to a plethora of ordered states and intriguing phases. We theoretically analyze a subset of vertex-sharing frustrated lattices, built up by corner sharing superconducting triangles interrupted by 0-Josephson junctions on two edges and a π-Josephson junction on the third edge. Such lattices have multiple degenerate free energy minima composed of different patterns of vortices/antivortices (V/AV) penetrating each triangle. Exemplary for the Kagome lattices with periodically arranged 0- and π-Josephson junctions, we identify various classical and quantum phases. We derive an effective Ising-type spin Hamiltonian, describing the interaction between V/AVs. Strongly anisotropic long-range interactions between well separated V/AVs emerge from the constraints due to flux quantization in any hexagon loop. In the classically frustrated regime, we calculate the temperature-dependent spatially averaged spin polarization m(T) characterizing the crossover between the ordered and disordered V/AV states. In the coherent quantum regime, we analyze the lifting of the degeneracy of the ground state and the appearance of the highly entangled states[1].

[1] O. Neyenhuys, M. Fistul and I. Eremin, Long-range Ising spins models emerging from frustrated Josephson junctions arrays with topological constraints, PhysRevB.108.165413 (2023)

Keywords: Network; Frustration