Macroscopic Many-Qubit Interactions in Superconducting Flux Qubits

TL;DR

This paper explores macroscopic many-qubit interactions in superconducting flux qubits, presenting a general Hamiltonian and discussing observable Ising and tunnel-exchange interactions for studying complex many-body systems.

Contribution

It introduces a comprehensive low-energy Hamiltonian for N flux qubits, highlighting observable many-qubit interactions and their potential for simulating artificial spin systems.

Findings

Derived a general low-energy Hamiltonian for N flux qubits.

Identified observable Ising and tunnel-exchange interactions.

Proposed flux qubit systems as platforms for studying many-body physics.

Abstract

Superconducting flux qubits are considered to investigate macroscopic many-qubit interactions. Many-qubit states based on current states can be manipulated through the current-phase relation in each superconducting loop. For flux qubit systems comprised of $N$ qubit loops, a general expression of low energy Hamiltonian is presented in terms of low energy levels of qubits and macroscopic quantum tunnelings between the many-qubit states. Many-qubit interactions classified by {\em Ising type- or tunnel-}exchange interactions can be observable experimentally. Flux qubit systems can provide various artificial-spin systems to study many-body systems that cannot be found naturally.