Boosting Computational Power through Spatial Multiplexing in Quantum Reservoir Computing
Kohei Nakajima, Keisuke Fujii, Makoto Negoro, Kosuke Mitarai, Masahiro Kitagawa · Physical Review Applied · 2019
$Q\phantom{\rule{0}{0ex}}u\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}u\phantom{\rule{0}{0ex}}m$ $r\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}v\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}r$ $c\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}m\phantom{\rule{0}{0ex}}p\phantom{\rule{0}{0ex}}u\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}g$ provides a scheme for exploiting the natural dynamics of quantum systems as a computational resource. An NMR spin-ensemble system is a realistic candidate for implementing the framework, which is currently available in laboratories. Considering realistic experimental constraints, the authors propose a spatial multiplexing technique to effectively boost the platform's computational power. This scheme exploits disjoint dynamics of multiple, different quantum systems driven by common input streams in parallel. This allows one to prepare a huge number of qubits from individually small quantum systems, which are easy to handle in experiments.