In Ian Fleming’s first novel, James Bond returns from the Royale-les-Eaux casino to his hotel room and inspects it for signs of intrusion. First, he confirms that a hair carefully placed inside his writing desk has not been moved. He then checks that talcum powder on a cupboard handle is free of fingerprints. Lastly, he confirms that the water level in the lavatory water cistern hasn’t changed. Satisfied, he settles down to contemplate his larger mission.
Today, Bond would not find it so easy to be sure of his privacy. His secrets would be stored not in rooms, but on computers. And when he needed to share those secrets in the safest modern way, he would rely on complicated devices that use quantum physics, the science of the small. These devices look like Jenga puzzles, full of valves, chambers, lasers and lenses. How on earth could Bond possibly be sure it was safe to use them?
“Quantum devices are very difficult to characterize. You don’t want to depend on the details,” said Mateus Araújo of the Austrian Academy of Sciences. “If you do, then you are vulnerable to hacking.”
But almost from the devices’ conception three decades ago, there were hints that these vulnerabilities might not be a problem. Theorists went on to prove that, amazingly, all the users had to do to ensure privacy was to have the devices play a game. Simply winning — with a high enough score — would prove that no one else could be listening.
Now, two different experiments based in Oxford and Munich have demonstrated this process, known as device-independent quantum key distribution. A third experiment, based in Shanghai, concurrently demonstrated many of the necessary requirements. Each of the three groups of researchers had to carefully engineer complete cryptographic systems out of quantum components.
To read more, click here.