In any quantum computing system, quantum bits, namely qubits, act as memory cells and basic computing devices simultaneously. To perform complex computations, qubits must be able to interact with each other, and ensuring this remains a major obstacle to the development of large-scale quantum computers. To solve this problem, Wolfgang Lechner (Wolfgang Lechner), Philipp Hauke ​​(Philipp Hauke) and Peter Zoller (Peter Zoller) proposed a new quantum computer architecture in 2015, named LHZ after the first letters of their surnames. developers.

“This architecture was initially focused on solving tasks in the field of optimization,” recalls Wolfgang Lechner, a scientist in the Department of Theoretical Physics at the University of Innsbruck, Austria, “We then redesigned this architecture and minimized the optimization tasks as much as possible. that it can be resolved somehow.” .

Physical qubits in the LHZ architecture provide relative coordination of qubits with other qubits. “This means that not all qubits of a computing system need to interact with each other,” explains Wolfgang Lechner, “and we have now shown that the LHZ parity architecture is also suitable for building a universal quantum computer.”

Computers built on the basis of the parity architecture can operate with two or more qubits, using a single qubit as a “middleman”. “Some of the current quantum computers are already capable of performing such operations, although so far only on a very small scale,” says Michael Fellner, a member of the research group.

As a demonstration of the LHZ architecture’s capabilities, the researchers ran the quantum Fourier transform, the fundamental “block” of many quantum algorithms, on their parity computers. The companion system was able to solve this task in significantly fewer steps and therefore much faster than other systems. “We’ve also shown that the strong parallelism applied in architecture makes it possible to execute the famous Shor’s algorithm for factoring numbers more quickly and efficiently,” says Michael Fellner.

A two-level automatic error correction system is also implemented in the LHZ architecture. At the same time, errors that are detected and corrected quite simply, such as “bit inverse” or “phase error”, are corrected at the hardware level. And other, more complex types of errors are corrected using special software.

Now Wolfgang Lechner and Magdalena Hauser have formed a new company called ParityQC. Working with partners from the scientific and industrial sectors, the company’s experts are engaged in the further development of a next-generation quantum computer based on the LHZ architecture, which will be used to solve practical problems of various kinds.