Mironowicz Piotr, Horodecki Paweł, Horodecki Ryszard
International Centre for Theory of Quantum Technologies, University of Gdansk, Wita Stwosza 63, 80-308 Gdansk, Poland.
Department of Algorithms and System Modeling, Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology, Gabriela Narutowicza 11/12, 80-233 Gdansk, Poland.
Entropy (Basel). 2022 Mar 28;24(4):467. doi: 10.3390/e24040467.
We study the non-perfect propagation of information for evolving a low-dimensional environment that includes self-evolution as well as noisy initial states and analyse the interrelations between the degree of objectivization and environment parameters. In particular, we consider an analytical model of three interacting qubits and derive its objectivity parameters. The numerical analysis shows that the quality of the spectrum broadcast structure formed during the interaction may exhibit non-monotonicity both in the speed of self-dynamics of the environment as well as its mixedness. The former effect is particularly strong, showing that-considering part of the environment as a measurement apparatus-an increase of the external magnetic field acting on the environment may turn the vague measurement into close to ideal. The above effects suggest that quantum objectivity may appear after increasing the dynamics of the environment, although not with respect to the pointer basis, but some other, which we call the generalized pointer or indicator basis. Furthermore, it seems also that, when the objectivity is poor, it may be improved, at least by some amount, by increasing the thermal noise. We provide further evidence of this by analysing the upper bounds on distance to the set of states representing perfect objectivity in the case of a higher number of qubits.
我们研究信息的非完美传播，以演化包括自我演化以及噪声初始状态的低维环境，并分析客观化程度与环境参数之间的相互关系。特别地，我们考虑一个由三个相互作用的量子比特组成的解析模型，并推导其客观性参数。数值分析表明，在相互作用过程中形成的频谱广播结构的质量，在环境的自动态速度及其混合程度方面可能呈现非单调性。前一种效应尤为显著，这表明——将环境的一部分视为测量装置——作用于环境的外部磁场的增加可能会使模糊的测量变得接近理想状态。上述效应表明，量子客观性可能会在环境动力学增加之后出现，尽管不是相对于指针基，而是相对于其他一些基，我们称之为广义指针或指示基。此外，似乎当客观性较差时，至少可以通过增加热噪声在一定程度上加以改善。我们通过分析在更多量子比特情况下到表示完美客观性的状态集的距离上限，进一步证明了这一点。
