Using noise for QIP
We usually think of noise, and the interaction with any external environment that “measures” the state of a quantum information processing device, as the “enemies” of quantum information processing. This is because they destroy the delicate coherence between the different parts of a quantum system. So, it came as a surprise to discover that noise can also be a friend to quantum information processing. In some circumstances, a measurement or other interaction with the outside world can be used to force a system into a known quantum state – for example, one in which its constituent parts have non-local correlations or ‘entanglement’. This strategy of exploiting noise is set to become more important as the more intrinsically noisy solid-state systems become used for quantum information processing.
For further information please contact Peter Knight (Imperial) at mailto:p.knight@imperial.ac.uk
A schematic of one of the experiments devised by the IRC collaboration to demonstrate the positive effects of interactions with the outside world. In this setup the absence of a particular detector signal (or ‘click’) forces two atoms into a quantum-correlated (‘entangled’) state.