Quantum channel-estimation with particle loss: GHZ versus W states

TL;DR

This paper investigates how particle loss affects quantum channel estimation accuracy using GHZ and W states, focusing on the quantum Fisher information for depolarizing and phase-flip channels.

Contribution

It compares the robustness of GHZ and W states in quantum channel estimation under particle loss, providing insights into optimal state choices.

Findings

W states are more robust to particle loss than GHZ states.

Particle loss significantly reduces estimation precision for both states.

Quantum Fisher information decreases with increasing particle loss.

Abstract

We consider quantum channel-estimation for depolarizing channels and phase-flip channels extended by ancilla qubits and fed with a GHZ or W state. After application of the channel one or several qubits can be lost, and we calculate the impact of the loss on the quantum Fisher information that determines the smallest uncertainty with which the parameters of these channels can be estimated.