The stuff that quantum memories are made of: an international team of physicists has succeeded, for the first time, in storing a quantum bit in a diamond for longer than one second at room temperature. The researchers did not use a natural diamond like the one shown here, however, neither was it cut. They produced their diamond artificially by depositing carbon containing one hundredth of a percent of the heavy carbon isotope C-13 and a small quantity of nitrogen from the gas phase onto a substrate. The diamond they obtained in this way had an edge length of a few millimetres.
Credit cards which are completely fraud-proof and passports which cannot be forged: quantum physics could make both of these possible. This is explained by the fact that the quantum mechanical state of a particle, an atomic nucleus, for example, can be neither copied nor read out correctly without additional information which only authorised users of possible cards have. Accordingly, if a credit card were to contain a quantum memory, it would be protected against misuse. Although physicists have already developed methods to write quantum states into different types of memory and read them out again, the problem is either that these methods work only just above absolute zero temperature which excludes routine use – or that the quantum information stored is lost after only a few milliseconds. Researchers at Harvard University in Cambridge near Boston, the Max Planck Institute of Quantum Optics in Garching, and Caltech in Pasadena have now successfully stored a quantum state in a diamond crystal for more than a second at room temperature. The researchers even believe that a storage time of one-and-a-half days is possible if they improve their method.
via Quantum storage system with long-term memory.
