(NMR) studies, the dynamical decoupling (DD) approach to decoherence suppression has attracted tremendous interest. The central idea of DD is to use a control pulse sequence to effectively decouple a quantum system from its environment. During the past years several DD pulse sequences have been proposed. The so-called “bang-bang" control has proved to be very useful [@BangBang1; @BangBang2; @exp2] with a variety of extensions. However, it is not optimized for a given period $T$ of coherence preservation. The Carr-Purcell-Meiboom-Gill (CPMG) sequence from the NMR context can suppress decoherence up to $O(T^{3})$ [@UDDexact]. In an approach called “concatenated dynamical decoupling" [@CDD1; @CDD2], the decoherence can be suppressed to the order of $O(T^{N+1})$ with $2^{N}$ pulses. Remarkably, in considering a single qubit subject to decoherence without population relaxation, Uhrig’s (optimal) dynamical decoupling (UDD) pulse sequence proposed in 2007 can suppress decoherence up to $O(T^{N+1})$ with only *N* pulses [@UDDexact; @UDDprl; @key-12]. In a UDD sequence, the $j$th control pulse is applied at the time $$\begin{aligned}
 \label{Tj} T_{j} & =T \sin^{2}(\frac{j\pi}{2N+2}),\
j=1, 2\cdots ,N.\end{aligned}$$ In most cases UDD outperforms all other known DD control sequences, a fact already confirmed in two beautiful experiments [@UDDvsCPMG; @detailpra; @Du-Liu]. As a dramatic development in theory, Yang 