Lages J, Dobrovitski V V, Katsnelson M I, De Raedt H A, Harmon B N
Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2005 Aug;72(2 Pt 2):026225. doi: 10.1103/PhysRevE.72.026225. Epub 2005 Aug 31.
We numerically investigate decoherence of a two-spin system (central system) by a bath of many spins 1/2. By carefully adjusting parameters, the dynamical regime of the bath has been varied from quantum chaos to regular, while all other dynamical characteristics have been kept practically intact. We explicitly demonstrate that for a many-body quantum bath, the onset of quantum chaos leads to significantly faster and stronger decoherence compared to an equivalent non-chaotic bath. Moreover, the non-diagonal elements of the system's density matrix, the linear entropy, and the fidelity of the central system decay differently for chaotic and non-chaotic baths. Therefore, knowledge of the basic parameters of the bath (strength of the system-bath interaction, and the bath's spectral density of states) is not always sufficient, and much finer details of the bath's dynamics can strongly affect the decoherence process.
我们通过由多个自旋1/2组成的量子比特池，对一个双自旋系统（中心系统）的退相干进行了数值研究。通过仔细调整参数，量子比特池的动力学状态已从量子混沌转变为规则状态，而所有其他动力学特性实际上保持不变。我们明确证明，对于多体量子比特池，与等效的非混沌量子比特池相比，量子混沌的出现会导致明显更快、更强的退相干。此外，中心系统密度矩阵的非对角元素、线性熵以及保真度在混沌和非混沌量子比特池中的衰减方式不同。因此，仅了解量子比特池的基本参数（系统-量子比特池相互作用强度以及量子比特池的态密度谱）并不总是足够的，量子比特池动力学的更细微细节会强烈影响退相干过程。
