That’s the quantum internet, which builds on the laws governing quantum mechanics, with the promise of “unhackable” transmissions. For four decades now, there has been continuous progress in the field, but what has remained elusive is scale — connecting more than two devices on a quantum network has been daunting.
It sounds like something straight out of spy fiction. When someone breaks into a transmission and tries to intercept it — the message is destroyed. That’s the quantum internet, which builds on the laws governing quantum mechanics, with the promise of “unhackable” transmissions. For four decades now, there has been continuous progress in the field, but what has remained elusive is scale — connecting more than two devices on a quantum network has been daunting. For the first time, a group of scientists has found a scalable process, connecting eight devices on a quantum network in Bristol.
“This is the largest entanglement-based quantum communication network. Multinodal networks like this have not been built before,” said Siddarth Joshi from the University of Bristol’s Quantum Engineering Technology lab, who led the study with a team of 15 under the UK National Quantum Communications Hub project. “We have been able to show this on a city-wide scale. Think of how we can start connecting cities. Could we link this to a satellite? These are things we want to do.”
Quantum networks use light particles, called photons, to communicate. It relies on a process called entanglement. “Say, I have a deck of cards and you have another. You choose a card at random, I do too. These are different decks. The card you choose has no correlation with the one I choose,” Joshi explained. “But if the decks are ‘entangled’, the card you choose would be identical to the one I do.”
India’s telecom sector, in the efforts of enabling policies including more quantum of the spectrum, is set to establish new benchmarks in the next-generation network deployments and service delivery.
What has held back the creation of large-scale networks is the technology it has relied on so far. Trusted nodes. “It’s like having children’s walkietalkies. One set talks to another, and if you want to send a message to a third person, you have to listen to the message from one walkie-talkie and repeat it into the other,” Joshi explained. So, if eight people wanted to communicate, they’d need 56 walkie-talkies — one for each of the seven others in the network.
Joshi and his team figured there could be a workaround — wavelength multiplexing. “You take light, you split light based on its colour (i.e. wavelength) so you now have many entangled states. You distribute the various wavelengths to various users. You do this simultaneously and everyone can talk to everyone else,” he said. Present-day computers use the RSA protocol (Rivest-Shamir-Adleman, named after the developers) to encrypt and decrypt messages. https://telecom.economictimes.indiatimes.com