In a study recently published in Nature Physics, the Jiuzhang team demonstrated for the first time experimentally that quantum teleportation achieves an unconditional advantage over direct transmission through lossy channels when transmitting single photons.

Quantum Teleportation Achieves Unconditional Advantage

Photons are ideal carriers for long-distance quantum information transmission. However, they suffer rapid decay in optical fibers or free space due to channel losses that scale exponentially with distance (for example, approximately 15–20 dB loss per 100 kilometers of fiber). This presents a core challenge in quantum communication.

Quantum teleportation can theoretically bypass this limitation: rather than transmitting the physical photon itself, it transfers the quantum state using pre-shared entanglement resources paired with classical communication. Nevertheless, remote preparation of entanglement is equally constrained by channel losses, resulting in extremely low efficiency for conventional entanglement distribution.

To overcome this bottleneck, the research team proposed and implemented an all-optical entanglement swapping scheme. By utilizing three pairs of spontaneous parametric down-conversion (SPDC) entangled photon sources—combined with dual Bell-state measurements (BSM) at remote and relay nodes—they achieved event-triggered entanglement generation. This approach effectively suppresses multi-photon noise and improves the overall availability of entanglement distribution.

Experimental Scheme

Experimental results show that under an equivalent 100-kilometer channel condition (approximately 15 dB loss), the scheme achieves an entanglement heralding efficiency of ~82% and an entanglement fidelity of 0.775. Building on this, the team performed single-photon quantum teleportation, achieving a transmission efficiency approximately 2.95 times higher than direct transmission, alongside a fidelity of 0.826—substantially exceeding the classical limit (2/3).

In short, this work provides the first experimental proof that quantum teleportation not only bypasses theoretical channel loss constraints, but also achieves true unconditional advantage under realistic, non-ideal conditions. Following their milestones in quantum computational advantage [Science 370, 1460–1463 (2020)] and quantum precision measurement advantage [Phys. Rev. Lett. 130, 070801 (2023)], this marks another major advantage breakthrough by the Jiuzhang team in quantum information science.

From Cutting-Edge Research to Education: Quantum Teleportation Experimental System

Leveraging years of deep expertise in quantum teleportation, our team successfully bridged the gap between frontier experiments and educational demonstrations. The quantum teleportation process based on SPDC entangled light sources can now be demonstrated and validated using our Quantum Teleportation Experimental System.

Quantum Teleportation Experimental System

The system generates polarization-entangled photon pairs via spontaneous parametric down-conversion (SPDC). An arbitrary polarization state is prepared on one photon and modulated through a Mach-Zehnder interferometer before undergoing joint Bell-state measurement with the other photon. By utilizing hybrid path-polarization degrees of freedom, the system achieves complete discrimination among all four Bell states. Based on the measurement outcomes, feed-forward operations are performed on the target photon to reconstruct the remote quantum state, completing the entire experimental chain of quantum teleportation.

While stably outputting entangled photon pairs, the system measures and analyzes quantum state correlation properties, Bell inequality violations, and final-state transmission fidelity, making the underlying physical processes directly observable.

Key performance benchmarks include:

• High Brightness: Single-channel count rate > 1×10⁵ cps

• High Entanglement Yield: > 5×10³ cps

• Pronounced Quantum Nonlocality: Bell inequality violation value > 2.4

• High Fidelity: Final state fidelity > 0.6

These core metrics are fully sufficient to intuitively showcase the complete picture of quantum teleportation experiments.

Overall, the system translates critical physical mechanisms into repeatable, measurable procedures. It provides an intuitive presentation of core steps—including entanglement generation, quantum state encoding, and remote reconstruction—offering a robust platform for foundational quantum information research and laboratory instruction.

Paper Link: https://www.nature.com/articles/s41567-026-03348-7