The indisputable quantum money can be stored in an ultra -kol ‘debit card’

Rudimentary quantum debit card that can be imposed on an unforgivable quantum money is made of extremely cold atoms and light particles.

In the usual banks, detecting forged banknotes often depends on the skill of forgery, but in the quantum bank the law of physics called the theorem without cloning would prevent successful forgery. This law cites identical copies quantum information Simply cannot be made and, in 1983, physicist Stephen Wiesner has designed a protocol that uses the theorem for non-cloning to create Independent currency. Julien Laurat In the Laboratory of Kastler Brossel in France and his colleagues, they have now implemented this idea in the most advanced experiment.

In this protocol, the bank issues banknotes made of quantum particles that have a special set of properties – a specific quantum condition – and are Protected from forgery The theorem of the non-class. Laurat says that the protocol itself is a seminar paper in quantum cryptography, but has never been implemented in such a way that the user could store quantum money – fragility of quantum conditions means that the user would have to spend it immediately.

His team enabled such storage by integrating Memory devices Similarly, I claim the disco in their placement. In his experiment, the user communicates with a quantum device that plays the role of a bank by exchange of light particles or photons. The condition of each photon can be disposed of in memory, analogous to load the debit card.

The memory device of the team is made of several hundred million atoms of Cesia that the researchers have cooled to just a few million degrees above the absolute zero by hitting them with lasers. To this extreme temperatureThe quantum states of atoms could be controlled very precisely by light, but Laurat says it took years to determine how to do good enough to act as part of a quantum debit card with cold-atomic memory. Through repeated tests, he and his colleagues have shown that photons can be effectively downloaded from atoms when the user wants to spend their quantum money, and that those countries are corrupt in the process.

Christoph Simon At the University of Calgary, Canada, he says that a new experiment is a step in the direction of full quantum money, but the storage time of quantum memory, which is approximately 6 million seconds, is still too short to make the protocol practical. “More [future step] is to increase transparency. I think the long -term goal, especially in the context of quantum money, would be a quantum memory you can put in your pocket. But we’re definitely not there yet, “he says.

The team has its own perspectives to increase the storage time – if it has been a thousand times longer, the protocol could be used in the box Metropolitan quantum networks It already exists in cities around the world, Laurat says. In addition, the most modern quantum memories could enable Ultra for sure quantum distance communication In addition to helping you connect several quantum computers to one, a more powerful device, he says.