Uniaxial Dynamical Decoupling Of Quantum Many-spin System

Noise in mesoscopic physics,it exists in nature since the system we focus on,such as logical qubit(Two-level system),Bose-Einstein condensate(BEC),inevitably couples with environment,which causes dissipation or decoherence(relaxation and dephasing).In terms of quantum information,in order to ensure credible fidelity of multi-pass quantum gate operations,the key we focus on is to erase the effect.For the propose,researchers seek for lots of systems,such as solid quantum system(quantum dot,N-V center and quantum spin system etc.),Bose-Einstein condensate system,superconducting quantum circuit,anyons in topological insulator,Cluster state,Rydberg state in ultracold atom,quantum optic systems.In this paper,we propose a protocol of uniaxial dynamical decoupling in classical and quantum circumstances.For quantum environment,we account spin bath in quantum dot for it,since the limit of simulation ability,we set bath size N=20;for classical environment,we attempt the classical random noise(white noise,power spectrum is same)for the mixed spin in BEC system.Shortly,the current schemes of dynamical decoupling are introduced,for examples,single-axis protocols(Hahn echo and CPMG),and two-axis protocol(PDD,CDD).We raise a new method called uniaxial dynamical decoupling(Uni-DD),with the premises of prolonging the two orders of magnitude of coherence time,it excels Hahn echo(with the help of the same high bias field,if not it fails to make it),and it overmatches two-axis PDD scheme,and reduces the difficulty of lab operation.In consideration of the sensibility of rotation angle for pulse in Uni-DD protocol,we develop modulation Uni-DD(m-Uni-DD)scheme by the inspiration of CPMG protocols,we adjust the nearby pulse direction and enhance the robustness of m-Uni-DD.We look forward to applying the new technology into popular nuclear magnetic resonance(NMR)systems and generalizing to different implementation schemes for quantum information fields.