Quantum technologies, which leverage the principles of quantum mechanics, have been found to outperform their classical counterparts on specific tasks. Among other things, past studies have highlighted the potential of quantum systems that can enable long-distance communication, using photons (i.e., particles of light) to carry quantum information.
Despite their promise, quantum communication systems are often prone to photon loss, the scattering, absorption or disappearance of traveling photons. This photon loss becomes increasingly pronounced as transmission distances increase.
One proposed approach for reducing photon loss relies on a process known as quantum teleportation. This process entails the transfer of a quantum state from one particle to another without moving the particle to a different location, via a phenomenon known as quantum entanglement.
Researchers at the University of Science and Technology of China recently demonstrated the advantage of quantum teleportation over the direct transmission of photons in long-distance quantum communication. Their paper, published in Nature Physics, introduces a new approach to prepare entangled photons remotely and realize quantum teleportation.
“In quantum information science, we have reached a stage where a central goal is no longer simply to demonstrate fascinating quantum effects, but to show that quantum technologies can outperform the best classical alternatives in well-defined tasks,” Chaoyang Lu, co-senior author of the paper, told Phys.org. “Such demonstrations are key milestones on the road toward practical quantum information technologies. A good example from our own work is Jiuzhang, the photonic quantum computer we demonstrated in 2020, which showed quantum computational advantage using photons.”
Quantum physicists have been exploring the idea of quantum teleportation for more than four decades. This elegant protocol enables the transfer of an unknown quantum state without physically transmitting the particle that carries this state.
“Over the years, our group has explored teleportation in increasingly complex systems, including multiple degrees of freedom and high-dimensional quantum states,” said Lu. “After these proof-of-principle experiments, we began to ask a very simple question: in a real experiment, can teleportation transmit a photonic qubit more efficiently than simply sending the photon directly through the same lossy channel?”
Comparing quantum teleportation and direct single-photon transmission
When reviewing previous research, Lu and his colleagues realized that no studies had experimentally compared quantum teleportation with the direct transmission of photons. One reason for this is that teleportation only works well if the shared entanglement between distant nodes is realized effectively, and this has proved difficult so far.
“This observation became the starting point of our work,” said Lu. “We wanted to take this clean, fundamental protocol and let it compete head-to-head with direct transmission—almost as if putting teleportation and ordinary photon transmission in the same ring. Using photons as flying qubits, we developed an all-optical scheme to create high-efficiency heralded entanglement and then used it for teleportation through a lossy channel.”
To clearly demonstrate experimentally that quantum teleportation can outperform the most straightforward classical approach for transmitting information using photons, the researchers first designed a new all-optical scheme to prepare entanglement between photons. This scheme allowed them to remotely prepare pairs of entangled photons, even when communication channels are susceptible to photon loss.
“This scheme can be viewed as an unconditional version of entanglement swapping: out of six generated photons, we measure four of them, and those measurement results herald the creation of a high-quality EPR (Einstein-Podolsky-Rosen) pair in the remaining two photons,” explained Lu. “Crucially, this heralded pair is prepared in a way that largely avoids the loss suffered in direct transmission.”
Lu and his colleagues simulated and experimentally characterized the process by which their scheme enables the preparation of entangled photon pairs, measuring important quantities such as heralding efficiency and fidelity. Subsequently, they used the heralded EPR pair they produced as the resource to realize teleportation via a carefully calibrated lossy channel with a transmission of approximately 1%.
“By measuring both the efficiency and fidelity of the teleported photonic states, we found that teleportation was nearly three times more efficient than direct transmission, even when the latter was enhanced by optimal quantum cloning,” said Lu. “This demonstrated the unconditional advantage of our teleportation scheme.”
Toward the practical implementation of quantum teleportation
This study brings the idea of quantum teleportation one step closer to real-world implementation. Other research groups could soon draw inspiration from the team’s scheme to develop similar approaches for realizing quantum teleportation.
“Quantum teleportation has long been regarded as an elegant way to transfer quantum states without physically sending the particle itself,” said Lu. “What we show here is that, under realistic photon-loss conditions, this idea can do more than illustrate a fundamental principle: it can outperform direct transmission.
“Practically, this suggests a promising route toward more efficient quantum communication and future quantum networks. By using heralded entanglement as a resource, teleportation can help overcome the severe photon loss that limits long-distance optical quantum channels.”
The team’s findings further highlight the potential of teleportation and could contribute to the future development of quantum relays, repeaters and connected quantum processors. Lu and his colleagues are now planning further tests aimed at demonstrating their scheme’s potential outside well-controlled laboratory settings, using real optical-fiber links and quantum networks.
“Showing a teleportation advantage under realistic network conditions would be an important next step toward practical applications,” added Lu. “At the same time, we hope to extend the method beyond simple EPR pairs and develop efficient heralded preparation of more complex entangled states, such as GHZ states. These resources could enable more powerful protocols in quantum networks and help demonstrate genuine quantum advantages in communication, distributed computing and networked quantum information processing.” https://phys.org/news/2026-07-quantum-teleportation-photon-loss-distance.html
Recent Comments