Decoherence dynamics of entangled quantum states in the XXX central spin model

Abstract

Maintaining coherence of a qubit is of vital importance for realizing a large-scale quantum computer in practice. In this work, we study the central spin decoherence problem in the XXX central spin model (CSM) and focus on the quantum states with different initial entanglement, namely intra-bath entanglement or system–bath entanglement. We analytically obtain their evolutions of fidelity, entanglement, and quantum coherence. When the initial bath spins constitute an N-particle entangled state (the Greenberger–Horne–Zeilinger-bath or the W-bath), the leading amplitudes of their fidelity evolutions both scale as $$\mathscr {O}(1/N)$$ , which is the same as the case of a fully polarized bath. However, when the central spin is maximally entangled with one of the bath spins, the amplitude scaling of its fidelity evolution declines from $$\mathscr {O}(1/N)$$ to $$\mathscr {O}(1/N^2)$$ . That implies appropriate initial system–bath entanglement is contributive to suppress central spin decoherence. In addition, with the help of system–bath entanglement, we realize quantum coherence-enhanced dynamics for the central spin where the consumption of bath entanglement is shown to play a central role.