Home Technology Stable quasiparticles promise more accurate quantum computers

Stable quasiparticles promise more accurate quantum computers

Stable quasiparticles promise more accurate quantum computers

Separation of electron charge into three parts – artistic concept
(source: Eric Anderson/University of Washington)

In an effort to create quantum computers that work with fewer errors, scientists are trying to “split” electrons into quasiparticles with very high resistance to external disturbances. Progress in this area is reported by Nature and Science magazine.

Researchers at the University of Washington claim to have found signs of promising topological qubits – anions. Even before that, scientists proposed to use topological quantum computing and anions as qubits, but practical and even experimental application of the concept did not come. A new discovery promises a breakthrough in this direction.

In general, topological quantum computing involves the use of topological qubits, which differ from ordinary qubits in that they have a very high resistance to external perturbations. And this means that the quantum system will be error-free even with a fairly large number of qubits.

American scientists report reliable detection of signs of fractional Hall effect (FQAH). The discovery marks the first and most promising step in building a fault-tolerant qubit, since FQAH states can contain all sorts of strange “quasi-particles” that have only a fraction of the charge of an electron.

Certain types of anions can be used to create so-called “topologically secure” qubits, resistant to any small local perturbations, Russian physicist Alexei Kitaev previously predicted. He suggested for the role of topological qubits to use two-dimensional topological phases with anions in which the Hall effect is observed.

The American scientists’ discovery really sets a new paradigm for the future of quantum physics with partial excitations, said Xiaodong Xu, the paper’s lead author and distinguished professor of physics, materials science and engineering at the University of Washington.

The scientists were able to achieve the claimed effect in an experiment with two “flakes” of a two-dimensional semiconductor material such as molybdenum telluride (MoTe2). One atom-thick plate is placed on top of another and slightly rotated so that the atomic lattices form a moiré. As a result, the electrons arrange themselves into a structure that reproduces a new exotic form of matter with its own properties.

The new structure exhibits magnetism without the application of an external magnetic field. And if under normal conditions the strongest magnetic fields are needed for the appearance of the quantum Hall effect, which puts an end to the practical value of the phenomenon, then in the new state of matter the internal magnetism leads to the appearance of this effect and of anions (“splitting” of the charge of the interacting electrons of fractional and stable parts).

Hence the stability of qubits and the possibility of their bound or entangled state – all that is needed for stable quantum computing. In addition, the proposed platform promises to help in the study of other equally exotic quasiparticles, also proposed by Kitaev as candidates for topological qubits – non-Abelian anions.

“The new type of topological qubit will be fundamentally different from those that can be created now,” said University of Washington physicist Eric Anderson, lead author of the Science paper and co-author of the Nature paper.

“The strange behavior of non-Abelian anions would make them much more reliable as a platform for quantum computing,” the scientist believes.


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