Near-perfect Noisy Quantum State Teleportation

TL;DR

This work addresses high-fidelity quantum teleportation under non-Markovian dephasing by introducing a timing-based protocol that exploits a decoherence-free subspace at Alice’s wing and coordinates with Bob’s local noise. By discarding BM outcomes that accumulate dual-wing noise (phi+ and phi-) and using the DFS-protected outcomes (psi+ and psi-), the average teleported-state fidelity FTS becomes independent of Alice’s noise and is governed by Bob’s decoherence factor b_{\\tau} and the entanglement of the shared resource. The authors derive explicit FTS expressions for both pure entangled and Werner-type mixed resources, showing near-unity fidelity can be achieved even with modest entanglement and in regimes where Bell-CHSH violations may be absent; they connect these results to a non-Markovian spin-boson model with Ohmic spectral density and provide photonic-qubit feasibility discussions. The work highlights measurement-timing and environment engineering as practical levers for robust quantum networking in structured environments, offering a general strategy for noise-resilient open-system quantum information tasks.

Abstract

Achieving high fidelity of quantum teleportation (QT) in a noisy environment is an essential requirement for its real-world applications. To this end, we devise a distinctive protocol for ensuring teleportation fidelity {\it close to unity}, hinging essentially on the timing of Alice's Bell-basis measurement (BM) dependent on the choice of Bob's local noise parameters, but is independent of Alice's local noise. Our scheme is enabled by Alice communicating to Bob only two of the BM outcomes corresponding to the states that are decoherence-free under common dephasing at Alice's wing. On the other hand, Bob is asked to discard the states of his qubit for the other two BM outcomes in order to maximize fidelity of the teleported state. This ensures the teleportation fidelity's independence of noise parameters in Alice's wing. We formulate the protocol in terms of a generic two-level quantum system, subjected to non-Markovian dephasing noise, applicable for any pure maximally/non-maximally entangled state as well as a Werner-type mixed state as resource. Notably, we show that high fidelity is achievable even using resource states with small values of the entanglement measure. Remarkably, even within the local regime of Werner states, where Bell-CHSH inequalities are not violated, the teleportation fidelity remains significantly high. Finally, we discuss the empirical feasibility of our scheme using photonic qubits.

Figures (3)

• Figure 1: The two qubits of Alice $A_1$ and $A_2$ are interacting with a common dephasing environment. The qubit $B$ at Bob's end evolves under another local dephasing noise, while $A_2$ and $B$ are entangled. Alice suitably times her Bell-basis measurement (BM) on $A_1$ and $A_2$ according to Bob's noise parameters and communicates to Bob $1.5$ bits of information corresponding to the appropriately chosen BM outcomes. Subsequently, Bob performs suitable unitary operations to complete the teleportation of state from $A_1$ to $B$.
• Figure 2: We present the average fidelity of the teleported state ${\cal F}_P(b_{\tau})$ as a function of $\tau$- the Bell-basis measurement timing at Alice's wing. The concurrence of the shared pure entangled state is fixed at $\mathcal{C}_{p} = 0.8$, and the system-environment coupling strength at Bob's wing is set to $\gamma = 0.1 \omega_0$. The panels (a)-(d) illustrate the results for different cutoff frequencies: (a) $\Lambda = 0.05\omega_0$, (b) $\Lambda = 0.2\omega_0$, (c) $\Lambda = 0.5\omega_0$, and (d) $\Lambda = 5.0\omega_0$, respectively.
• Figure 3: We present the average fidelity of the teleported state ${\cal F}_M(b_{\tau})$ as a function of $\tau$, the Bell-basis measurement timing at Alice's wing. The concurrence of the shared mixed entangled state is fixed at $\mathcal{C}_{m} = 0.8$, and the system-environment coupling strength at Bob's wing is set to $\gamma = 0.1 \omega_0$. The panels (a)-(d) illustrate the results for different cutoff frequencies: (a) $\Lambda = 0.02\omega_0$, (b) $\Lambda = 0.03\omega_0$, (c) $\Lambda = 0.05\omega_0$, and (d) $\Lambda = 0.07\omega_0$, respectively.