Abstract The teleportation of Quantum Fisher Information (QFI) is central to the precision limits of distributed quantum metrology, yet it is inevitably degraded by environmental decoherence. Here we investigate QFI teleportation under composite Pauli channels and show that a quantum switch can improve the outcome-resolved and success-probability-weighted QFI relative to the corresponding fixed-order protocol. The enhancement arises from a coherent reorganization of Pauli error trajectories rather than from a reduction of the physical error probabilities. For the three binary pairs of anti-commuting Pauli channels studied here, we identify a heralded branch whose normalized state has the ideal QFI whenever that branch has nonzero probability. These findings highlight the potential of utilizing quantum switches to mitigate Pauli-noise-induced QFI degradation in quantum communication and sensing networks.
Abstract The teleportation of Quantum Fisher Information (QFI) is central to the precision limits of distributed quantum metrology, yet it is inevitably degraded by environmental decoherence. Here we investigate QFI teleportation under composite Pauli channels and show that a quantum switch can improve the outcome-resolved and success-probability-weighted QFI relative to the corresponding fixed-order protocol. The enhancement arises from a coherent reorganization of Pauli error trajectories rather than from a reduction of the physical error probabilities. For the three binary pairs of anti-commuting Pauli channels studied here, we identify a heralded branch whose normalized state has the ideal QFI whenever that branch has nonzero probability. These findings highlight the potential of utilizing quantum switches to mitigate Pauli-noise-induced QFI degradation in quantum communication and sensing networks.
Abstract The teleportation of quantum Fisher information (QFI), a crucial protocol for remote quantum metrology, is fundamentally limited by decoherence in the entangled channel. Here, we propose and numerically analyze an enhanced scheme that incorporates a conditional flip operation (WM-QMR-Flip), transforming the protocol into an active, preemptive strategy for protecting the teleportation of QFI through a correlated generalized amplitude damping noise channel. Our results demonstrate that this active scheme significantly enhances the teleported QFI across a wide range of environmental parameters, including temperature and interaction time. We reveal the existence of an optimal set of measurement and reversal strengths that maximizes QFI recovery, while also characterizing the inherent trade-off between the degree of protection and the success probability of the protocol. Most significantly, we find a synergistic effect between our protection scheme and the channel’s memory; the QFI improvement increases monotonically with the channel correlation parameter, demonstrating that our protocol effectively leverages environmental memory as a resource. We conclude by discussing the feasibility of implementing this robust protection scheme on a linear optical platform, paving the way for more resilient distributed quantum sensing networks.
The purpose of quantum teleportation is to achieve perfect transmission of quantum information from one site to another distant site. In the teleportation process, the quantum system is inevitably affected by its surrounding environment, causing the system to lose its coherence, which will result in distortion of the transmitted information. In recent years, weak measurement and measurement reversal have been proposed to suppress the decoherence of quantum entanglement and protect some quantum states. On the other hand, quantum Fisher information (QFI) is an important physical quantity in quantum metrology, which can give the optimal value estimating the accuracy of parameters. As is well known, QFI is highly susceptible to environmental noise and can lead its measurement accuracy to decrease. Therefore, it is of great importance to examine how to protect QFI from being influenced by the external circumstance during the teleportation procedure. In this paper, we study how to improve the QFI of teleporting a single-qubit state via a Greenberger-Horne-Zeilinger state in a finite temperature environment with the technique of weak measurement and weak measurement reversal. According to different qubit transmission cases of three quantum teleportation schemes, we consider their respective QFIs in detail. After constructing the quantum logic circuit of each teleportation scheme, we first analyze the variance trend of QFI against the generalized amplitude damping noise parameters. Then by introducing weak measurement and measurement reversal on each noise particle of the three schemes, we optimize the related partial measurement parameters and explore the corresponding improved QFI, namely, the difference between the QFI with optimal partial measurements and that without partial measurements. We find that optimizing partial measurements can efficiently enhance the QFI of the teleported state for the three kinds of teleportation schemes at finite temperature. Moreover, with the value of p fixed, the lower the environment temperature, the larger the value of the improved QFI is. Our results could be useful in further understanding the applications of weak measurement and measurement reversal to the quantum communication process and may shed light on estimating some relevant quantum parameters and implementing quantum information tasks.
From the perspective of quantum information transmission, one may be interested in the teleportation of quantum Fisher information (QFI) which provides the optimal precision of parameter estimation. In this paper, we investigate the teleportation of QFI under the correlated amplitude damping (CAD) decoherence. It is found that the correlated effects play a positive role in improving the teleported QFI, but the impact of decoherence is still serious. Therefore, we propose two schemes, which are based on weak measurement (WM) and environment-assisted measurement (EAM), to enhance the teleportation of QFI under the CAD decoherence. The results show that both schemes can significantly improve the teleported QFI with a certain success probability. The findings of our study suggest that the correlated effects can significantly increase the success probabilities of these two schemes. A detailed comparison confirms that the EAM scheme is more efficient than the WM scheme in improving the teleportation of QFI.
We analytically characterize how the location and the local or correlated structure of stochastic Pauli errors affect a three-qubit coherent quantum-teleportation circuit. Independent local channels and a fully correlated two-qubit channel are inserted separately in six configurations. Propagating each Pauli-error realization through the Clifford circuit yields the effective channel on Bob's qubit and analytical expressions for the average and state-resolved fidelities. Under a common ordered-pair probability convention, the six configurations form three pairs that induce equivalent reduced channels on Bob. Within each pair, corresponding Pauli-error realizations have the same probabilities and produce the same effective Pauli operator on Bob's output state. The equivalence therefore holds for every input state within the stochastic Pauli models considered here, rather than only for the average fidelity. Correlated Z errors do not affect the output for the first pair; local X and Z errors exhibit complementary qubit sensitivity for the second; and correlated same-axis Pauli errors cancel for the third. These results classify the error response of the selected circuit configurations and show that it depends jointly on the error statistics, Pauli axis, and position within the protocol.
Quantum teleportation is designed to send an unknown quantum state between two parties. In the perspective of remote quantum metrology, one may be interested in teleporting the information that is encoded by physical parameters synthesized by quantum Fisher information (QFI). However, the teleported QFI is often destroyed by the unavoidable interaction between the system and the environment. Here, we propose two schemes to improve the teleportation of QFI in the non-Markovian environment. One is to control the quantum system through the operations of weak measurement (WM) and corresponding quantum measurement reversal (QMR). The other is to modify the quantum system based on the monitoring result of the environment (i.e., environment-assisted measurement, EAM). It is found that, in the non-Markovian environment, these two schemes can improve the teleportation of QFI. By selecting the appropriate strengths of WM and QMR, the environment noise can be completely eliminated and the initial QFI is perfectly teleported. A comprehensive comparison shows that the second scheme not only has a higher probability of success than the first one, but also has a significant improvement of the teleported QFI.
Abstract Quantum Fisher Information (QFI), which sets the fundamental bound on parameter estimation precision via the quantum Cramér-Rao inequality, is investigated for a general single-mode Gaussian state before and after teleportation. Using a two-mode squeezed vacuum state as a shared entanglement resource between Alice and Bob, we analyze the teleportation protocol under environmental noise, focusing on diffusion and dissipation induced by a thermal bath. By comparing QFI for several parameters of the input state before and after teleportation, we evaluate the effectiveness of QFI transfer. We find that increasing the squeezing of the shared state enhances QFI preservation. Notably, under certain conditions, environmental interactions can help maintain QFI, particularly for shared states with high frequency, suggesting a subtle interplay between system dynamics and decoherence.