Construction plan for fault tolerant qubits
Interference-free circuit designed for quantum computers
Billed as the fastest computers of the future, expectations for quantum computers are correspondingly high. But there are still a number of hurdles to overcome before they can be realized. One of these challenges is the fragility of the quantum bits, or qubits for short. Until now, the various perturbations could only be eliminated with great effort. A team from the two JARA partners Forschungszentrum Jülich and RWTH Aachen University, led by JARA professor David DiVincenzo, has now presented a design for a circuit with passive error correction that would simplify the construction of quantum computers.
Until the realization of a quantum computer with a large number of interleaved qubits, several challenges still have to be overcome. In order to reliably encode quantum information, several unstable qubits are usually combined to form a so-called logical qubit. Quantum error correction (QEC) codes make it possible to detect and subsequently correct errors in individual qubits so that the quantum information is preserved over a longer period of time.
Proposed hardware implementation of the QEC code. The circuit consists of two Josephson junctions coupled by a gyrator, highlighted in red.
© M. Rymarz et al., Phys Rev X (2021), https://doi.org/10.1103/PhysRevX.11.011032 (CC BY 4.0)
However, the application of such an active error correction in a quantum computer is very complex, which is why the scientists around JARA professor David DiVincenzo, head of the JARA Institute for Quantum Information, together with experts from Aachen, Jülich, the University of Basel and QuTech Delft, have been researching for new solutions. The scientists result is a design of a superconducting circuit with built-in error correction. In contrast to conventional circuits, this is designed in such a way that it is inherently protected against disturbances from the environment and can still be controlled. The concept thus bypasses the need for active stabilization in a highly hardware-efficient manner and would therefore be a promising candidate for a future quantum processor that has a large number of qubits.
"“I hope that our work will inspire efforts in the lab; I recognize that this, like many of our proposals, may be a bit ahead of its time”, said David DiVincenzo, Founding Director of the JARA-Institute for Quantum Information at RWTH Aachen University and Director of the Institute of Theoretical Nanoelectronics (PGI-2) at Forschungszentrum Jülich. “Nevertheless, given the professional expertise available, we recognize the possibility to test our proposal in the lab in the foreseeable future”.
The results of the work were published Feb. 17 in Physical Review X. To the original publication: