Researchers at QuTech – a collaboration between Delft University of Technology and TNO – have designed a record six silicon-based spin qubits in a fully interoperable array. Importantly, qubits can run at a low error rate that is achieved through a new chip design, automated calibration procedure, and new methods for initializing and reading qubits. These advances will contribute to the development of a scalable silicon-based quantum computer. The results have been published in temper nature today.
Various materials can be used to produce qubits, the quantum counterpart of a part of the classical computer, but no one knows which materials would be best for building a large-scale quantum computer. So far there have been only smaller demonstrations than silicon Quantum chips with high quality qubit operations. Now, researchers from QuTech, led by Professor Levin Vandersiben, have produced a six-qubit chip of silicon that operates at low error rates. This is a major step toward an error-tolerant quantum computer using silicon.
To make qubits, individual electrons are placed in a linear array of six.quantum dotsSpaced 90 nanometers. The array of quantum dots is made in a silicon chip with structures very similar to a transistor — a common component in every computer chip. A quantum mechanical property called spin is used to define a qubit with its orientation that defines a 0 or 1 logic state: the team used tuned microwave radiation with precision, magnetic fields, and electrical potentials to control the spin and measure individual electrons and make them interact with each other.
“The challenge of quantum computing today has two parts,” first author Mr. Stephan Phillips explained. “Developing qubits of good enough quality, and developing an architecture that allows one to build large systems of qubits. Our work fits both categories. And since the overall goal of building a quantum computer is an enormous effort, I think it is fair to say that we have made a contribution to the direction the correct “.
Electron spin is a sensitive property. Small changes in the electromagnetic environment cause the direction of rotation to fluctuate, and this increases the error rate. The QuTech team built on their previous experience engineering quantum dots with new methods for preparing, controlling, and reading the spin states of electrons. Using this new arrangement of qubits, they can create Logic gates, logic gates Systems of two or three electrons are entangled, depending on demand.
Quantum arrays containing more than 50 qubits have been produced using superconducting qubits. However, it is the global availability of silicon engineering infrastructure that gives silicon quantum devices the promise of an easier transition from research to industry. Silicon brings certain engineering challenges, and until this work from the QuTech team, arrays of up to three qubits can only be designed in silicon without sacrificing quality.
“This paper demonstrates that through precision engineering, it is possible to increase the number of silicon spin qubits while maintaining the same precision of individual qubits. The main building block developed in this research can be used to add more qubits in the following iterations of co-author Dr. Matthews,” said co-author Dr. Matthews. Madzik.
“In this paper, we push the qubit-count envelope in silicon, achieving high initialization accuracy, high readout accuracy, high single-qubit gate fidelity, and high secondqubit “What really stands out is that we demonstrate all of these properties together in one experiment on a record number of qubits,” said Professor Vandersypen.
Lieven Vandersypen et al, Universal control of a six-qubit quantum processor in silicon, temper nature (2022). DOI: 10.1038 / s41586-022-05117-x
Delft University of Technology
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