European scientists have completed a project to use holes instead of electrons in semiconductors as spin qubits.
“Holes” – hypothetical elementary particles in semiconductors – can be used as qubits – “computing blocks” of quantum computers. The research results were published in the scientific journal Nature Materials.
Two years of research has resulted in quantum entanglement and hole control effects in thin layers of semiconductor compounds. It is the holes that react to weaker magnetic fields, which makes it possible to reduce noise in quantum computers and create computers with a large number of qubits.
The question of using holes as qubits – positively charged quasiparticles with a charge equal to the charge of an electron – scientists were engaged in the MaGnum project (Majorana bound states in Ge / SiGe heterostructures), which was completed in March 2021. The project was recognized as a success since in the course of laboratory experiments, multilayer thin-film structures with spin qubits from holes were created.
Scientists from a compound of germanium and silicon have created an almost two-dimensional environment for limited movement of holes. The outer shells of the medium (layer) were made of silicon, on which the gates for controlling the holes were made – in fact, transistors. Applying voltage to the gates generated electromagnetic fields in the connection. The fields forced the “holes” in the two-dimensional layer to manifest themselves in one way or another and to interact with each other.
“Holes” have an almost complete set of quantum-mechanical properties like an electron. They also carry spin and interact with each other when approaching. But to control “holes” requires only 10 mT of magnetic field strength. It is noteworthy that this is several times less than for electron control. This is extremely critical for cryogenic spintronics, which does not tolerate strong magnetic fields well. This is why holes are great candidates for qubits for semiconductor quantum computers.