Inter-qubit coupling and qubit connectivity in a processor are crucial for achieving high fidelity multi-qubit gates and efficient implementation of quantum algorithms. Typical superconducting processors employ relatively weak transverse inter-qubit coupling which are activated via frequency tuning or microwave drives. Here, we propose a class of multi-mode superconducting circuits which realize multiple transmon qubits with all-to-all longitudinal coupling. These "artificial molecules" directly implement a multi-dimensional Hilbert space that can be easily manipulated due to the always-on longitudinal coupling. We describe the basic technique to analyze such circuits, compute the relevant properties and discuss how to optimize them to create efficient small-scale quantum processors with universal programmability.
@article{arxiv.1711.01658,
title = {Multi-mode superconducting circuits for realizing strongly coupled multi-qubit processor units},
author = {Tanay Roy and Madhavi Chand and Anirban Bhattacharjee and Sumeru Hazra and Suman Kundu and Kedar Damle and R. Vijay},
journal= {arXiv preprint arXiv:1711.01658},
year = {2018}
}
Comments
16 pages, 12 figures; Revised version with three new sections and updated references