Coherent single spin controlled in a quadruple quantum dot system
Coherent single spin controlled in a quadruple quantum dot system lead image
Quantum dots are vital to realizing quantum computers, especially at the industry level. These systems, made of semiconducting material, are only tens of nanometers wide and are sufficiently small that their properties differ from the same material at larger scales. The spins of electrons in quantum dots can store quantum bits of information, or qubits. Environmental disturbances do not affect the spins of electrons in quantum dots, protecting the qubits, and the more quantum dots in a system, the more qubits that are available.
But additional quantum dots make it more difficult to control and coordinate a system’s electron spins. For the first time, authors were able to coherently manipulate four individual electron spins in each dot of a linearly coupled quadruple quantum dot device.
Thus far, the quadruple quantum dot device is the largest to demonstrate coherent control of single electron spins. Author Takumi Ito said that this work is an important step for quantum information processing.
Using micro-magnet electron spin resonance, Ito et al. excited individual electron spins, and then enhanced this signal with correlated double sampling. This allowed them to observe the coherent spin manipulations known as Rabi oscillations. Previously, quadruple quantum dot systems have demonstrated incoherent spin manipulations, but never Rabi oscillations.
Building on this work, the authors want to investigate how to improve single spin manipulation methods and the quality of the Rabi oscillations in quadruple quantum dot devices. They would also like to attempt to manipulate single spins in a quintuple QD device.
Source: “Four single-spin Rabi oscillations in a quadruple quantum dot,” by Takumi Ito, Tomohiro Otsuka, Takashi Nakajima, Matthieu R. Delbecq, Shinichi Amaha, Jun Yoneda, Kenta Takeda, Akito Noiri, Giles Allison, Arne Ludwig, Andreas D. Wieck, and Seigo Tarucha, Applied Physics Letters (2018). The article can be accessed at https://doi.org/10.1063/1.5040280 .
