A record number of six, Silicon-based, spin qubits have been created by researchers at QuTech. The qubits can be operated with a low error-rate thanks to a new chip design, an automated calibration procedure, and new methods. It will be possible to build a quantum computer with these advances. Today's results are published in Nature.
There are different materials that can be used to make qubits, the quantum analogue to the classical computer, but no one knows which material will be best to build a large-scale quantum computer. There have only been small demonstrations of quantum chips. Researchers from QuTech have created a six qubit chip that operates with low error rates. This is a big step in the direction of a fault tolerant quantum computer.
Individual electrons are put in a linear array of six quantum dots. The structure of the quantum dots is very similar to the transistor in a computer chip. The 0 or 1 logical state is defined by the spin of a qubit. Microwave radiation, magnetic fields, and electric potentials were used to control and measure the spin of individual electrons.
The quantum computing challenge is comprised of two parts. Developing qubits that are of good enough quality and an architecture that allows one to build large systems of qubits are two things that need to be done. Our work is in either category. Since the goal of building a quantum computer is enormous, we have made a contribution in the right direction.
The spin of the electron is not easy to understand. The direction of spin can be affected by small changes in the environment. New methods for preparing, controlling, and reading the spin states of electrons were developed by the QuTech team. They could entangle systems of two or three electrons using this new arrangement of qubits.
Superconducting qubits have been used in the production of a quantum array. The promise of easier migration from research to industry is made possible by the global availability of Silicon engineering infrastructure. Until this work from the QuTech team, only up to three qubits could be engineered in Silicon without compromising quality.
The paper shows that it is possible to increase the Silicon spin qubit count while maintaining the same precision as for single qubits. In the next iteration of the study, the key building block developed in this research could be used to increase the number of qubits.
Prof. Vandersypen said that they push the envelope of the number of qubits in Silicon. In one single experiment on a record number of qubits, we show all these characteristics together.
More information: Lieven Vandersypen et al, Universal control of a six-qubit quantum processor in silicon, Nature (2022). DOI: 10.1038/s41586-022-05117-x Journal information: Nature
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