IIT Delhi transmits entangled quantum photons and classical data together over a 50-km optical fibre

Key facts

• Researchers at the Indian Institute of Technology (IIT) Delhi demonstrated the transmission of quantum-entangled photons alongside classical data over a 50-km optical fibre link.
• The research was funded by IIT Delhi's Institute of Eminence (IoE) grant and the National Quantum Mission (NQM), and has been published in the journal Optics Communication.
• Classical optical signals are typically much stronger than quantum signals and can generate noise that may disturb or obscure delicate quantum states, making integration with existing telecommunications infrastructure technically challenging.
• Quantum entanglement is a fundamental phenomenon underpinning emerging quantum technologies, including quantum key distribution (QKD) for securing the exchange of sensitive information.
• Using the same fibre infrastructure for quantum and classical signals could make future quantum networks more scalable and cost-effective to deploy.