Researchers from the high house of studies and the National Center of Competence in Research (NCCR) based their study on a type of qubit that uses the spin (intrinsic angular momentum) of an electron or a hole, reported the journal Nature Physics.

Qubits are the basis of a quantum computer, ensuring the processing, transfer and storage of data, for which it is necessary to achieve stable and fast interactions between a large number of qubits whose states can be reliably controlled from abroad.

According to the new experiment, it would be feasible to integrate millions of qubits on a single chip with processes already consolidated in the international microelectronics industry.

To solve the problem of arranging and linking thousands of qubits, the University of Basel and the NCCR used the spin of a hole, which can be completely controlled electrically, without the need for additional components such as micromagnets on the chip.

A team led by Dr. Andreas Kuhlmann achieved for the first time a controllable interaction between two qubits within this configuration: they managed to couple two qubits and cause a controlled spin of one of their spins, depending on the state of the spin of the other, known as controlled spin.

As Kuhlmann highlighted, hole spins make it possible to create two-qubit gates that are fast and high fidelity; this principle, he confirmed, now also made it possible to couple a greater number of pairs of qubits.

The energy exchange of holes is not only electrically controllable, but is also anisotropic as a consequence of spin-orbit coupling, meaning that the spin state of a hole is influenced by its motion through space, the source explained.

According to the review, experimental and theoretical physicists from the University of Basel and the NCCR SPIN proved that anisotropy makes two-qubit gates possible without the usual trade-off between speed and fidelity.

Hole spin-based qubits not only take advantage of proven silicon chip manufacturing, but are also highly scalable and have proven to be fast and robust in experiments, the text states.

This approach, the report summarizes, has great potential in the race to develop a large-scale quantum computer.

In the opinion of experts, quantum computing could increase processing speed, complex problem solving and storage capacity, as well as the complexity of cryptographic security and large-scale data optimization for fields such as artificial intelligence.

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