Modular quantum computation in a trapped ion system

Abstract

Modern computation relies crucially on modular architectures, breaking a complex algorithm into self-contained subroutines. A client can then call upon a remote server to implement parts of the computation independently via an application programming interface (API). Present APIs relay only classical information. Here we implement a quantum API that enables a client to estimate the absolute value of the trace of a server-provided unitary operation U. We demonstrate that the algorithm functions correctly irrespective of what unitary U the server implements or how the server specifically realizes U. Our experiment involves pioneering techniques to coherently swap qubits encoded within the motional states of a trapped 171Yb+ ion, controlled on its hyperfine state. This constitutes the first demonstration of modular computation in the quantum regime, providing a step towards scalable, parallelization of quantum computation. © 2019, The Author(s).