A new quantum communication method uses the temporal Talbot effect to simplify high-dimensional quantum key distribution.
As digital communication accelerates and cyber threats continue to rise, researchers are searching for safer ways to transmit sensitive information. One promising approach is quantum cryptography, which uses individual photons to generate encryption keys that cannot be secretly intercepted.
Scientists at the Faculty of Physics at the University of Warsaw have now designed and tested a new system for quantum key distribution (QKD) within an urban fiber network. Their method uses what is known as high-dimensional encoding. The setup is simpler to construct and expand than many current systems, yet it relies on a physical phenomenon first described nearly 200 years ago, called the Talbot effect. The findings were published in the journals Optica Quantum, Optica, and Physical Review Applied.
“Our research focuses on quantum key distribution (QKD) – a technology that uses single photons to establish a secure cryptographic key between two parties,” says Dr. Michał Karpiński, head of the Quantum Photonics Laboratory at the Faculty of Physics, University of Warsaw. “Traditionally, QKD employs so-called qubits – the simplest units of quantum information. While this method is already well tested, it does not always meet the requirements of more demanding applications. That’s why researchers are now working on multidimensional encoding. Instead of qubits, which yield one of two measurement outcomes, we use more complex quantum states that can take on multiple values.”
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