Scientists create fast switches for quantum computers

Scientists have found a way to create fast on/off switches for quantum systems. The technique uses a laser pulse that superimposes atoms and should be up to a thousand times faster than what was previously possible.

The circuitry for quantum computers was designed by the University of Surrey in Guildford, near London. According to the scientists, the technique works by superimposing a phosphorus atom in a silicon chip. Superposition more or less implies that a particle can be in the ‘on’ and ‘off’ state simultaneously, until it decays. This can be done, for example, by measuring the particle.

At the University of Surrey, researchers discovered that it is possible to superimpose the atoms with very short laser pulses. They then managed to superimpose the atom again within a few trillionths of a second; that happened the moment a second laser pulse hit the atom. With these short pulses it is therefore possible to quickly switch between different states.

During the experiments it was discovered that the state of superposition is also preserved when electrons ‘float’ around the phosphorus atom. This happens, for example, when power is applied to the system. The stability of superposition is important because it increases the reliability of the quantum information stored in the state of atoms.

The new technology should contribute to the development of quantum computers. The quick switching between ‘on’ and ‘off’ states should help to quickly perform calculations that work with qubits, the quantum variant of conventional bits. In the future, the researchers want to see whether they can scale up their switching method in order to make the building blocks for quantum computers larger.