Coupled-clusters and quantum computing

This talk presents predictions from coupled-cluster calculations of rare isotopes and first results from quantum computing an atomic nucleus. \\ Rare doubly-magic nuclei play an important role because they determine the structure of entire regions in the nuclear chart. In recent years, the computation of rare isotopes such as $^{48,52,54}$Ca, $^{78}$Ni, and $^{100}$Sn and their neighbors -- based on interactions from effective field theories of quantum chromodynamics\footnote{E. Epelbaum, H.-W. Hammer, and U.-G. Meiß{\s}ner, Rev. Mod. Phys. \textbf{81}, 1773 (2009); R. Machleidt and D. R. Entem, Phys. Rep. \textbf{503}, 75 (2011); A. Ekstr{\"o}m et al., Phys. Rev. C \textbf{91}, 051301 (2015).} and using controlled approximations only\footnote{B. R. Barrett, P. Navratil, and J. P. Vary, Prog. Part. Nucl. Pays. \textbf{69}, 131 (2013); G. Hagen et al., Rep. Prog. Phys. \textbf{77}, 096302 (2014); T. A. L{\"a}hde et al., Phys. Lett. B \textbf{732}, 110 (2014); H. Herbert et al., Phys. Rep. \textbf{621}, 165 (2016).} -- led to predictions for neutron skins\footnote{G. Hagen et al., Nature Physics \textbf{12}, 186 (2016).} and the evolution of shell structure in isotopes of calcium\footnote{G. Hagen et al., Phys. Rev. Lett. \textbf{109}, 032502 (2012).}, nickel\footnote{G. Hagen, G. R. Jansen, and T. Papenbrock, Phys. Rev. Lett. \textbf{117}, 172501 (2016).}, and tin\footnote{T. D. Morris et al., arXiv:1709.02786 (2017).}. \\ Quantum computers promise to reduce the computational complexity of simulating quantum many-body systems from exponential to polynomial. Very recently, quantum computing devices have started to solve small scale, but real-world many-body problems in chemistry and magnetism\footnote{P. J. J. O'Malley et al., Phys. Rev. X \textbf{6}, 31007 (2016); A. Kandala et al., Nature \textbf{549}, 242 (2017).}. This talk presents the quantum computation of the deuteron via cloud servers\footnote{E. F. Dumitrescu et al., arXiv:1801.03897 (2018).}. This is a first step towards scalable nuclear structure computation on a quantum processor unit via the cloud, and our results shed light on how to map scientific computing applications onto nascent quantum devices.