Universal Uhrig Dynamical Decoupling for Bosonic Systems

We construct efficient deterministic dynamical decoupling schemes protecting continuous-variable degrees of freedom. Our schemes target decoherence induced by quadratic system-bath interactions with analytic time dependence. We show how to suppress such interactions to Nth order using only N pulses. Furthermore, we show how to homogenize a 2m-mode bosonic system using only (N+1)2m+1 pulses, yielding - up to the Nth order - an effective evolution described by noninteracting harmonic oscillators with identical frequencies. The decoupled and homogenized system provides natural decoherence-free subspaces for encoding quantum information. Our schemes only require pulses which are tensor products of single-mode passive Gaussian unitaries and swap gates between pairs of modes.