Quantum fisher information protection of N-qubit Greenberger-Horne-Zeilinger state from decoherence

TL;DR

This paper proposes a scheme using quantum weak measurement and flip operations to protect N-qubit GHZ states and their quantum Fisher information from amplitude damping noise, achieving high fidelity and probability.

Contribution

It introduces an explicit protection scheme for GHZ states and their phase QFI against amplitude damping, with analytical optimization and high success rates.

Findings

Effective protection of average QFI for GHZ states.

High fidelity (>99%) and probability (up to 1) for generalized GHZ states.

Scheme outperforms existing methods in protecting quantum coherence.

Abstract

In this paper we study the protection of N-qubit Greenberger-Horne- Zeilinger (GHZ) state and generalized N-qubit GHZ states in amplitude damping channel by means of quantum weak measurement and flip operations. We derive the explicit formulas of the performances of the protection scheme: average fidelity, average probability and the average quantum fisher information (QFI). Moreover, the analytical results for maximizing the average fidelity and probability are obtained. We show that our scheme can effectively protect the average QFI of phase for GHZ states and generalized GHZ states. The proposed scheme has the merit of protecting GHZ state and the QFI of phase against heavy amplitude damping noise. Further we show that for some generalize GHZ state, the proposed scheme can protect the state with probability one and fidelity more than 99%.