Available control in dynamical decoupled quantum systems

Francesco Ticozzi, Augusto Ferrante

Yu Pan, Zairong Xi, Wei Cui

Dynamical decoupling (DD) eliminates qubit-bath coupling by applying a sequence of instantaneous pulses. While qubit-bath couplings generally lead to qubit relaxation and dephasing, qubit-qubit couplings are often used to manipulate or control quantum states. We investigate the available control operations in two DD schemes, named periodic DD (PDD) and Uhrig DD (UDD), to see whether universal quantum computation can be realized in these decoupled systems. We find that universal control is possible using Heisenberg interaction in both periodically decoupled system and Uhrig decoupled system, and the available control operations under two kinds of DD sequences obey the same commutation relation. In the UDD case, we also derive a rough bound for control errors.

Re-Bing Wu, Jing Zhang, Chunwen Li +2 more

Giorgio Anfuso, G. Piccitto, Vittorio Romano +2 more

Abstract We investigate dynamical decoupling operated by $$2\pi$$ 2 π -pulses in a two-level subspace of a multilevel system showing that it may lead to selective decoupling. This provides a flexible strategy for decoupling transitions in a quantum network, when control to directly address them is not available, which can be used to control internode interaction or actively suppress decoherence.

Manoj Kumar

Yutaka Tabuchi, Makoto Negoro, Masahiro Kitagawa

A method for synthesizing dynamical decoupling (DD) sequences is presented, which can tailor these sequences to a given set of qubits, environments, instruments, and available resources using partial information of the system. The key concept behind the generation of the DD sequences involves not only extricating the strong dependence on the coupling strengths according to the ``optimal control,'' but also exploiting the ``refocus'' technique used conventionally to obtain DD sequences. The concept is a generalized one that harmonizes optimal control and designing of DD sequences.