Researchers achieve breakthrough in unhackable quantum cryptography

Published on
July 27, 2023

In a groundbreaking experiment published in Nature this week, an international team of researchers from the UK, Switzerland, and France has successfully implemented a new form of quantum cryptography that offers unprecedented security guarantees.

Unlike existing quantum key distribution (QKD) methods which rely on communicating between 'trusted' quantum devices, the newly demonstrated approach allows secure encrypted communication between untrusted devices without requiring detailed knowledge about their internal workings.

Traditional cryptographic protocols used today derive their security from the computational inability of classical computers to factor large prime numbers efficiently. However, the development of powerful quantum computers in the future would render these methods obsolete by easily cracking such mathematical problems.

The research team's experiment, built on three decades of fundamental quantum research, has experimentally realized a complete QKD protocol that is provably secure against vulnerabilities or defects in the encryption devices themselves - a concept known as "device independence."

By exploiting the uniquely quantum phenomenon of entanglement, where particles exhibit an exclusive connection spanning any distance, the protocol guarantees privacy based solely on the validity of quantum theory itself, as certified by the measurement statistics observed.

"The real breakthrough is that we showed our quantum network achieves the theoretical performance required for this new kind of device-independent QKD in practice, and successfully distributed a shared secret key," explained Professor David Lucas, lead investigator on the project.

Unlike previous work that removed the assumption of limited computational power but still relied on trusting the quantum devices, this achievement guarantees communication security with only minimal assumptions about the underlying physical hardware.

"After decades studying how nature exploits these curious quantum effects, we can now harness the fundamental fabric of reality for practical applications in securing communications," said David Nadlinger, the paper's lead author.

Enabled by sustained investment from the UK's National Quantum Technologies Programme, this multi-disciplinary collaboration has taken a major step towards realizing an "ultimate, bug-proof" form of quantum cryptography immune to future quantum hacking threats.

You can find the paper on the Nature website here.