Scientists create room-temperature quantum state for record 39 minutes

Source:Xinhua Published: 2013-11-15 10:01:57

Researchers from Britain, Canada and Germany said Thursday they have successfully maintained a normally fragile quantum state at room temperature for a world record 39 minutes, overcoming a key barrier towards building ultrafast quantum computers.

In conventional computers data is stored as a string of 1s and 0s. In the experiment, quantum bits of information, or qubits, were put into a "superposition" state in which they can be both 1s and 0 at the same time, enabling them to perform multiple calculations simultaneously.

In the experiment, the researchers raised the temperature of a system, in which information is encoded in the nuclei of phosphorus atoms in silicon, from -269 degrees Celsius to 25 degrees Celsius and demonstrated that the superposition states survived at this balmy temperature for 39 minutes. Outside of silicon, the previous record for such a state's survival at room temperature was around two seconds.

The researchers even found that they could manipulate the qubits as the temperature of the system rose, and that they were robust enough for this information to survive being "refrozen," the optical technique used to read the qubits only works at very low temperatures.

"Thirty-nine minutes may not seem very long but as it only takes one-hundred-thousandth of a second to flip the nuclear spin of a phosphorus ion -- the type of operation used to run quantum calculations -- in theory over 20 million operations could be applied in the time it takes for the superposition to naturally decay by one percent," said Stephanie Simmons of Oxford University, an author of the paper in the US journal Science.

"Having such robust, as well as long-lived, qubits could prove very helpful for anyone trying to build a quantum computer," Simmons said in a statement.

Lead author Mike Thewalt of Simon Fraser University, Canada, believed that the study "opens up the possibility of truly long- term coherent information storage at room temperature."

There is still some work ahead before the team can carry out large-scale quantum computations. The nuclear spins of the 10 billion or so phosphorus ions used in this experiment were all placed in the same quantum state. To run calculations, however, physicists will need to place different qubits in different states.

"To have them controllably talking to one another -- that would address the last big remaining challenge," Simmons said.

Posted in: Others

blog comments powered by Disqus