Posted: April 27, 2009 |
Helpful quantum ghosts |
(Nanowerk News) The idea that far distant particles can somehow ’talk’ to each other worried Einstein so much that he called it ‘spooky action at a distance’.
|
Having confirmed its existence, scientists today are learning how to use this ‘spooky action’ as a helpful tool. Now a team of physicists at the University of Bristol and Imperial College London have harnessed this phenomenon to shed light on another unusual and previously difficult aspect of quantum physics - that of distinguishing between two similar quantum devices ("Experimental Quantum Process Discrimination").
|
In the everyday world any process can be considered as a black box device with an input and an output; if you wish to identify the device you simply apply inputs, measure the outputs and determine what must have happened in between.
|
But quantum black boxes are different. Distinguishing between them is impossible using only single particle inputs because the outputs are not distinguishable: a fundamental consequence of the laws of quantum mechanics is that only very few states of a quantum particle can be reliably distinguished from one another.
|
The Bristol-Imperial team has shown how to get around this problem using ‘spooky action’.
|
|
Anthony Laing, PhD student in the Department of Physics, who performed the study, said: “Apart from providing insight into the fundamentals of quantum physics, this work may be crucial for future quantum technologies.
|
“How else could a future quantum engineer build a quantum computer if they can’t tell which circuits they have?”
|
The new findings have implications for our understanding of quantum mechanics as well as the emerging potential of quantum information science.
|
This work was performed in the Bristol Centre for Quantum Photonics led by Professor Jeremy O’Brien as part of a collaboration with Dr Terry Rudolph at Imperial College London.
|