Gaining Control on Quantum Particle Environments

Scientists at the Delft University of Technology Kavli Institute for Nanosciences, in the Netherlands, have recently managed to gain new control over the environment of quantum particles, which may make it possible to finally construct a working quantum computer. The new finds essentially allow researchers to exercise greater control of single electrons, which is something absolutely necessary for the creation of the super-fast computers, ScienceDaily reports.

The investigations effort was coordinated by Lieven Vandersype, a Vidi winner, and the FOM workgroup leader. Details of the work appear in the August 16 issue of the respected scientific journal Nature Physics. The thing about quantum particles, the scientists say, is that they can exist in two states at the same time, something that is known as “superposition”. In practical applications, this means that the basic unit of a quantum computer, a quantum bit (qubit), may exist in both the “on” and “off” states. It can also exist in both the “1” and “0” configurations simultaneously.

In the case of electrons, superposition means that the spin of the particle may be facing opposite directions at any given time, a feat that is impossible at greater scales, or in other types of physics. Because there are more than one possible states for the elementary particle, the speed at which a processor employing superposition particles could operate would considerably exceed even the most advanced supercomputers in the world today, physicists say. However, up to this point, the main obstacle has been the fact that the environment in which the particles spin is also made up of quantum particles.

This causes significant disruptions of the quantum states, and renders any attempt at advancing this field of research useless. In a previous work, DUT investigators created a quantum box that allowed them to separate the electrons from the environment. In the new study, they learned that the spin of the nuclei in the quantum box was having an adverse effect on the spin of the targeted electrons. So they applied an electrical current on the box, which allowed them to control the spin of the atomic nuclei, which no longer spun randomly.

The paper detailing the finds was also published more recently in the scientific journal Physical Review Letters. A more comprehensive explanation of the theory involved was elaborated for the new edition by PhD student Jeroen Danon. Funding for the team's work came from the Foundation for Fundamental Research on Matter (FOM), and the NWO.