Researchers have shown through a study published in journal Physical Review X that it is possible to use modern-day ion-trap technologies to build large-scale quantum computers.
Prototypes of quantum computers are already available, but for them to reach their full potential they not only have to be made bigger, but they have to be made capable of processing errors. Quantum computers of today are still not able to fully handle complex computations because environmental noise and errors cause the system to get out of control, researchers say.
Classical computers use similar schemes to detect and correct errors during data storage and transfer: Before data is stored and transferred, redundancy is added to the data usually in the form of additional bits detecting and correcting errors. Scientists have developed comparable schemes for quantum computers, where quantum information is encoded in several entangled physical quantum bits.
“Here we exploit quantum mechanical properties for error detection and correction,” explains Markus Müller from Swansea University, Wales. “If we can keep the noise below a certain threshold, we will be able to build quantum computers that can perform quantum computations of arbitrary complexity by increasing the number of entangled quantum bits accordingly.”
Markus Müller and his colleague Alejandro Bermudez Carballo explain that in order to achieve this goal, the capabilities of the technological platforms have to be optimally exploited. They introduced new variants of fault-tolerant protocols and investigated how these can be implemented with currently available operations on quantum computers. The researchers found that a new generation of segmented ion traps offers ideal conditions for the process: Ions can be shuttled quickly across different segments of the trap array. Precisely timed processes allow parallel operations in different storage and processing regions. By using two different types of ions in a trap, scientists may use one type as carriers of the data qubits while the other one may be used for error measurement, noise suppression and cooling.
Building on the experimental experience of research groups in Innsbruck, Mainz, Zurich und Sydney the researchers defined criteria that will allow the scientists to determine whether the quantum error correction is beneficial. By using this information they can guide the development of future ion-trap quantum computers with the goal to realize a logical quantum bit in the near future that, owed to error correction, exceeds the properties of a pure physical quantum bit.