Cryptography is vital today to protect information online and keep it secure, whether that’s for ordinary folks doing online banking and shopping or for commercial organisations and governments wishing to keep commercial and state secrets confidential.
However, the advent of powerful quantum computers might leave such information vulnerable to attack.
To counter such a threat researchers at Bristol University’s Quantum Engineering Technology Labs (QETLabs) have developed tiny microchip circuits which exploit the strange world of quantum mechanics and provide a level of security enhanced by the laws of quantum physics.
These circuits distribute cryptographic keys using the quantum properties of entanglement, superposition and the absolute randomness provided by quantum behaviour, which is reproducible by no other means.
Principal investigator Professor Mark Thompson said: “The system we have developed allows information to be exchanged using single photons of light in a quantum state.
“If an eavesdropper hacks your transmission, they will collapse the fragile quantum states and the system will immediately alert you to their presence and terminate the transmission.”
This work, published in the February issue of Nature Communications, has demonstrated the world’s first chip-to-chip quantum secured communication system, using microchip circuits just a few millimetres in size.
This international collaboration, including researchers from Bristol, Glasgow and Japan’s NiCT in Japan, used commercial semiconductor chip manufacturers to make their devices – in much the same way as Intel pattern silicon to make the latest CPUs.
However, instead of using electricity these miniaturised devices used light to encode information at the single photon level, providing encryption keys with an unlimited lifetime.
The Bristol team has continued developing this technology, demonstrating an innovative design that allows the same functionality in a complementary metal-oxide-semiconductor (CMOS) compatible process, with the work being published in the February issue of Optica, the journal of the Optical Society.
Whereas the initial devices used a more expensive and complex manufacturing approach, these next generation devices are fabricated in standard silicon, paving the way for direct integration with microelectronic circuits.
This will ultimately lead to integration in everyday electrical devices, including laptops and mobile phones.