Large scale quantum computers will consist of many interacting qubits. In this paper we expand the two flux qubit coupling scheme first devised in [Phys. Rev. B {\bf 70}, 140501 (2004)] and realized in [Science {\bf 314}, 1427 (2006)] to a three-qubit, two-coupler scenario. We study L-shaped and line-shaped coupler geometries, and show how the interaction strength between qubits changes in terms of the couplers' dimensions. We explore two cases: the "on-state" where the interaction energy between two nearest-neighbor qubits is high, and the "off-state" where it is turned off. In both situations we study the undesirable crosstalk with the third qubit. Finally, we use the GRAPE algorithm to find efficient pulse sequences for two-qubit gates subject to our calculated physical constraints on the coupling strength.
@article{arxiv.1102.0307,
title = {Tunable coupling between three qubits as a building block for a superconducting quantum computer},
author = {Peter Groszkowski and Austin G. Fowler and Felix Motzoi and Frank K. Wilhelm},
journal= {arXiv preprint arXiv:1102.0307},
year = {2013}
}