Improved Bounded-Strength Decoupling Schemes for Local Hamiltonians

We address the task of switching off the Hamiltonian of a system by removing all internal and system-environment couplings. We propose dynamical decoupling schemes that use only bounded-strength controls for quantum many-body systems with local system Hamiltonians and local environmental couplings. To do so, we introduce the combinatorial concept of balanced-cycle orthogonal arrays (BOAs) and show how to construct them from classical error-correcting codes. The derived decoupling schemes may be useful as a primitive for more complex schemes, e.g., for Hamiltonian simulation. For the case of $n$ qubits and a two-local Hamiltonian, the length of the resulting decoupling scheme scales as $O(n \log n)$ , improving over the previously best-known schemes that scaled quadratically with $n$ . More generally, using BOAs constructed from families of Bose-Chaudhuri-Hocquenghem (BCH) codes, we show that bounded-strength decoupling for any $\ell $ -local Hamiltonian, where $\ell {\geq } 2$ , can be achieved using decoupling schemes of length at most $O(n^{\ell -1} \log n)$ .