[Paper Review] Enhancing Continuous Variable Quantum Teleportation using Non-Gaussian Resources

Eduardo Villaseñor, Robert Malaney|arXiv (Cornell University)|Oct 31, 2021

Quantum Information and Cryptography29 references6 citations

TL;DR

This paper proposes using optimized sequential photon addition and subtraction (PA-PS) operations to generate non-Gaussian resource states that significantly enhance continuous variable quantum teleportation fidelity over noisy channels. The method increases the maximum feasible teleportation distance by up to 40% in fiber links and over 70% in satellite-to-ground channels compared to traditional Gaussian two-mode squeezed vacuum states, particularly improving performance under high loss.

ABSTRACT

Continuous Variable (CV) non-Gaussian resources are fundamental in the realization of quantum error correction for CV-based quantum communications and CV-based computing. In this work, we investigate the use of CV non-Gaussian states as quantum teleportation resource states in the context of the transmission of coherent and squeezed states through noisy channels. We consider an array of different non-Gaussian resource states, and compute the fidelity of state teleportation achieved for each resource. Our results show that the use of non-Gaussian states presents a significant advantage compared to the traditional resource adopted for CV teleportation; the Gaussian two-mode squeezed vacuum state. In fiber-based quantum communications, the range of quantum teleportation is increased by approximately 40% via the use of certain non-Gaussian states. In satellite-to-ground quantum communications, for aperture configurations consistent with the Micius satellite, the viable range of quantum teleportation is increased from 700 km to over 1200 km. These results represent a significant increase in the performance of pragmatic and realizable quantum communications in both terrestrial and space-based networks.

Motivation & Objective

• To investigate the performance of various non-Gaussian resource states in enhancing continuous variable (CV) quantum teleportation over noisy channels.
• To address the limitation of existing works by performing a full optimization of the PA-PS operation parameters, which previous studies had not done.
• To compare the teleportation fidelity of coherent and squeezed states when using non-Gaussian resources (e.g., PA-PS, PS, PA, PC, QS, SB) against the standard Gaussian two-mode squeezed vacuum (TMSV) state.
• To evaluate the practical feasibility of these non-Gaussian states in real-world terrestrial (fiber) and space-based (satellite-to-ground) quantum communication networks.
• To quantify the improvement in teleportation range and fidelity robustness under realistic loss and excess noise conditions.

Proposed method

• The study employs a Wigner characteristic function formalism to model the teleportation process and compute the fidelity of teleported coherent and squeezed states.
• Non-Gaussian resource states are generated via sequential photon addition (PA) and subtraction (PS) operations, with optimization over the squeezing parameter r and gain g=1/η to maximize fidelity.
• The analysis includes five types of non-Gaussian states: photon subtraction (PS), photon addition (PA), photon catalysis (PC), quantum scissors (QS), and squeezed Bell-like (SB) states.
• Realistic channel models are used: for fiber, a linear excess noise model ϵ_fiber = aL + 6×10⁻⁴ with a=5.3×10⁻⁵ km⁻¹; for satellite-to-ground, transmissivity and excess noise depend on aperture sizes (rsat=15 cm, rgs=50 cm), with mean transmissivity T≈0.06 at 500 km and T≈0.002 at 1460 km.
• Fidelity is computed as a function of channel length L, with classical limit set at 2/3, and the maximum distance where fidelity exceeds this limit is reported.
• The performance of the optimized PA-PS state is compared against all other non-Gaussian states and the TMSV state across both channel types.

Experimental results

Research questions

• RQ1 Can optimized sequential PA-PS operations generate non-Gaussian resource states that outperform the standard Gaussian TMSV state in CV quantum teleportation fidelity?
• RQ2 How does the fidelity of teleported coherent and squeezed states vary when using different non-Gaussian resource states under realistic fiber and satellite-to-ground channel conditions?
• RQ3 What is the maximum distance over which teleportation fidelity exceeds the classical limit when using non-Gaussian resources compared to the TMSV state?
• RQ4 How does parameter optimization of the PA-PS operation affect the robustness and range of CV teleportation in high-loss environments?
• RQ5 To what extent do non-Gaussian states enhance the viability of practical CV quantum teleportation in terrestrial and space-based quantum networks?

Key findings

• The optimized PA-PS state increases the maximum teleportation distance for coherent states in fiber channels from 100 km (using TMSV) to 140 km, a 40% improvement.
• For squeezed states in fiber, the maximum distance where fidelity exceeds the classical limit increases from 38 km (TMSV) to 65 km (PA-PS), a 71% improvement.
• In satellite-to-ground channels, the PA-PS state extends the viable teleportation range from 700 km (TMSV) to over 1200 km, representing an increase of more than 80%.
• The SB state achieves the highest fidelity in low-loss regimes, but the PA-PS state outperforms all others in high-loss environments typical of long-distance quantum communication.
• Without parameter optimization, the PA-PS state fails to exceed 92 km in fiber and 610 km in satellite channels, demonstrating that optimization is essential for performance gains.
• The fidelity of teleported squeezed states remains below the classical limit in the satellite-to-ground channel for all distances considered, indicating a limitation of current non-Gaussian resource performance for this input state.