A quantum device capable of detecting and correcting its own errors has been developed, for the first time ever, by researchers at the University of California, Santa Barbara. This development could lead to the development of quantum computers, far faster than the fastest supercomputers available today.
Quantum bits (qubits) are the underlying basis of mathematical operations of theoretical quantum computers, much as ones and zeros are used by today's processors. Instead of two states - on, represented by one, and off, or zero - a qubit could exist in several intermediary states.
However, quantum bits are highly influenced by their environment, making them prone to error. They also regularly lose information stored in them, preventing their use (so far) in the development of quantum computing.
Quantum circuitry developed by UC Santa Barbara researchers allows qubits to interact with their neighbors in order to detect and correct errors which take place during normal operations. The system could allow for the development of reliable qubit processors that would radically outperform contemporary electronic designs.
Instead of storing information in a single qubit, the new system records information over several quantum bits. Nine qubits in the new circuitry are able to check one another for errors, and correct inconsistencies as they arise. This allows the network to protect and store data far longer than would be possible using a single qubit.
"This is the first time a quantum device has been built that is capable of correcting its own errors," Austin Fowler of UC Santa Barbara said.
In traditional computers, error correction is accomplished by reading the value of various bits. However, doing so with quantum bits would ruin the qubit due to quantum effects, defeating the purpose of error correction. Measuring a value locks it into place, preventing superpositioning.
"You can't measure a quantum state, and expect it to still be quantum," Rami Barends, post-doctoral researcher, said.
This system allows qubits to detect changes to neighbors, without having to read their original values.
The new quantum circuit is not nearly powerful enough to be used in a working processor. Quantum computers would require a processor utilizing tens of thousands of qubits. Before those can be developed, however, error correction techniques, like the one demonstrated by this latest circuit, need to be created.
Future research could run error correction tests for longer periods than have been accomplished so far, another advance which will be necessary in the drive to develop the world's first true quantum computers.