Researchers at Nanjing University achieve a significant milestone in quantum storage, opening doors to large-scale quantum networks.
Quantum technologies have been rapidly advancing, offering promising possibilities for enhanced computational power and communication security. However, to fully harness the potential of quantum devices, networking them is crucial. While classical devices can utilize existing fiber-optic networks, the reliable storage of quantum information at telecom wavelengths has remained a challenge. In a groundbreaking development, the group of Prof. Xiao-Song Ma at Nanjing University has achieved record-long quantum storage at telecom wavelengths, bringing practical large-scale quantum networks closer to reality.
Quantum Light vs. Classical Light:
Traditional signal amplification techniques used in classical telecommunications networks are unsuitable for preserving the unique properties of quantum states of light, known as entanglement. Quantum entanglement allows for stronger correlations between photons than classical light. The conversion of optical signals to electrical signals for amplification would cause the loss of these quantum correlations. Quantum repeaters offer a solution by storing and transforming the fragile entangled state into a new state that shares entanglement with the next node in the network.
The Challenge of Quantum Memories:
The development of quantum memories with sufficiently long storage times has been a significant challenge, particularly for photons at telecom wavelengths. The group led by Prof. Xiao-Song Ma has addressed this challenge by utilizing yttrium orthosilicate crystals doped with erbium ions. Erbium ions possess optical properties that align with existing fiber networks, making them an ideal choice for quantum storage. However, previous implementations of erbium-ion-based quantum memories were relatively inefficient.
Record-Breaking Storage Time:
The recent breakthrough by the team at Nanjing University demonstrates the storage and retrieval of entangled photons at telecom wavelengths with a remarkable storage time of close to two microseconds. This achievement is nearly 400 times longer than previous demonstrations in this field, marking a significant step towards practical applications. The researchers successfully preserved the entanglement of the photon pair even after storing it for 1936 nanoseconds, allowing for manipulation of the quantum state—a crucial requirement for quantum repeaters.
Integration and Future Prospects:
In addition to the extended storage time, the team combined their quantum memory with a novel source of entangled photons on an integrated chip. This integration of high-quality entangled photon generation and storage on a solid-state platform suitable for mass production holds great promise for the future of quantum networks. The compatibility of the erbium-ion-based quantum memories with existing large-scale fiber networks opens the door to the realization of a quantum internet.
Conclusion:
The achievement by the group at Nanjing University in achieving record-long storage of entangled photons at telecom wavelengths represents a significant milestone in the development of practical quantum networks. The successful preservation of entanglement and the integration of quantum memory with an integrated chip offer exciting possibilities for the future. As quantum technologies continue to advance, the realization of a quantum internet becomes increasingly feasible, bringing us closer to a new era of computing and communication.
Leave a Reply