“School of Nano-Sciences”
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| Paper IPM / Nano-Sciences / 18228 |
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We analyze the decoherence dynamics of a central spin coupled to a spin chain with a time-dependent
noisy magnetic field, focusing on how noise influences the system's decoherence. Our results show
that decoherence due to the nonequilibrium critical dynamics of the environment is amplified in the
presence of uncorrelated and correlated Gaussian noise. We demonstrate that decoherence factor
consistently signals the critical points, and exhibits exponential scaling with the system size, the
square of noise intensity, and the noise correlation time at the critical points. We find that strong
coupling between the qubit and the environment leads to partial revivals of decoherence, which
diminish with increasing noise intensity or decreasing noise correlation time. In contrast, weak
coupling leads to monotonic enhanced decoherence. The numerical results illustrate that, the revivals
decay and scale exponentially with noise intensity. Moreover, the revivals increase and indicate linear
or power law scaling with noise correlation time depending on how the correlated noise is fast or slow.
Additionally, we explore the non-Markovianity of the dynamics, finding that it decays in the presence
of noise but increases as the noise correlation time grows.
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