Simulating long-distance entanglement in quantum spin chains by superconducting flux qubits

TL;DR

This paper explores how superconducting flux qubits can be used to simulate long-distance entanglement in quantum spin chains, demonstrating a feasible method for preparing entangled states efficiently.

Contribution

It introduces two protocols for adiabatic simulation of long-distance entanglement using superconducting flux qubits with realistic parameters.

Findings

Successful adiabatic preparation of end-to-end entanglement in four-qubit chains

Protocols utilize dc currents and microwave fields for control

Feasible within realistic experimental parameters

Abstract

We investigate the performance of superconducting flux qubits for the adiabatic quantum simulation of long distance entanglement (LDE), namely a finite ground-state entanglement between the end spins of a quantum spin chain with open boundary conditions. As such, LDE can be considered an elementary precursor of edge modes and topological order. We discuss two possible implementations which simulate open chains with uniform bulk and weak end bonds, either with Ising or with XX nearest-neighbor interactions. In both cases we discuss a suitable protocol for the adiabatic preparation of the ground state in the physical regimes featuring LDE. In the first case the adiabatic manipulation and the Ising interactions are realized using dc currents, while in the second case microwaves fields are used to control the smoothness of the transformation and to realize the effective XX interactions. We demonstrate the adiabatic preparation of the end-to-end entanglement in chains of four qubits with realistic parameters and on a relatively fast time scale.