A new class of semiconductor nanocrystal to help create a quantum computer has been engineered by Dr Evgeny Chekhovich, from the Department of Physics and Astronomy, along with collaborators.
Traditional transistor-based digital computer circuits operate by switching macroscopic electric charges (electrons) and currents.
Quantum computers promise to outperform any classical digital computer, offering a tool to solve the most challenging problems in physics, chemistry, biology and beyond.
Decades of progress have resulted in semiconductor transistors using only hundreds of electrons, making further miniaturization of classical circuits impossible.
At present, the effort of the research community is focused on developing new concepts, which would allow miniaturization down to the level of individual atoms and electrons.
In particular, there is a strong interest in exploiting quantum states of atomic scale semiconductor systems to build quantum computing circuits, which would outperform any classical digital counterpart.
This work uses quantum dots, which are small (few thousand atoms) semiconductor crystals, that can hold individual electrons.
Over the past two decades, different teams have worked to use the magnetic moment of a single electron in a quantum dot as a basic quantum computing circuit.
But the atoms of the quantum dot also have magnetic moments, which disrupt quantum magnetism of the electron. This has hampered the progress in achieving working quantum circuits.
In the paper, Nuclear spin quantum register in an optically active semiconductor quantum dot, published in Nature Nanotechnology, Dr Evgeny Chekhovich, along with two collaborators from Johannes Kepler University Linz, in Austria approached this long-standing problem from a different angle.
Instead of treating atomic magnets as an obstacle, they were turned into a resource. This alternative approach led to successful development of an individual quantum dot into a fully-functioning two-qubit quantum processor.
“Building powerful quantum circuits is a challenging task, and multiple competing platforms are currently being developed,” said Dr Chekhovich.
“Quantum dots are particularly promising as they offer natural evolution from existing digital semiconductor technologies.
“There is a long road of research and development ahead, but the first step has been made, and epitaxial quantum dots have been proven to offer integrated-circuit solutions where quantum states of electrons, atoms and light particles will be used to achieve unprecedented computing power.”
