Electron spins initialised and read at room temperature

Quantum computers are based on qubits, which can have any value between 0 and 1. Spin qubits operate on the basis of their rotation – which can be clockwise, anticlockwise or in both directions at once. The first step is to assign each qubit a value of 1 or 0. Spin based qubits also require their atomic nuclei to spin in the same direction and this is commonly imparted using dynamic nuclear polarisation. The problem is this has yet to be demonstrated at room temperature. However, Linköping University researchers Yuttapoom Puttisong, Xingjun Wang, Irina Buyanova and Professor Weimin Chen have discovered a way of getting around this problem. Prof Chen and his research group had already developed a spin filter that works at room temperature; the filter lets through electrons with the desired spin direction and screens out the others. Using the spin filter, they have now produced a flow of free electrons with a given spin in gallium nitrogen arsenide. The researchers have also shown that polarisation of the nuclear spin can happen in less than 1ns. This is said to make it possible to control the polarisation of the spin in the nucleus electrically, allowing spin information to be initiated and read.