Perturbative Analysis of Quasi-periodic Patterning of Transmon Quantum Computers: Enhancement of Many-Body Localization

Abstract

Recently it has been shown that transmon qubit architectures experience a transition between a many-body localized and a quantum chaotic phase. While it is crucial for quantum computation that the system remains in the localized regime, the most common way to achieve this has relied on disorder in Josephson junction parameters. Here we propose a quasi-periodic patterning of parameters as a substitute for random disorder. We demonstrate, using the Walsh-Hadamard diagnostic, that quasiperiodicity is more effective than disorder for achieving localization. In order to study the localizing properties of our new Hamiltonian for large, experimentally relevant system sizes, we use two complementary perturbation-theory schemes, one with respect to the many-body interactions and one with respect to hopping parameter of the free Hamiltonian.