Measuring quantum measurement

Like so many things in the quantum realm measurement is slippery.

'Measurement is still a very enigmatic part of quantum mechanics,' Ian Walmsley, Head of Atomic & Laser Physics at Oxford, tells me. 'When you make a measurement there's been no way to know exactly what that measurement was doing.'

Ian likens previous approaches to 'dead reckoning' - the sort of guesstimates made by navigators before accurate timepieces enabled them to make exact measurements by the sun and the stars.

Now a new approach reported in Nature Physics, developed by a team led by Ian and Martin Plenio of Imperial College London [see the Imperial release], promises to reveal exactly what a quantum measurement device does, with the team showing how this idea can be applied to a photon detector that can sense the presence of multiple independent photons.

Whilst a detector with these abilities is likely to find uses in quantum communications and quantum computing it's the fundamental concept of 'measuring the measurers' that Ian believes is particularly important: 'This approach enables us to say what a measurement is doing without having to build a model of it. This could lead to us being able to properly calibrate many types of quantum devices with photon detectors being just one application.'

'We can now deal properly with both aspects of quantum mechanics, characterizing both the state and the measurement, it opens up new avenues for developing new kinds of measuring devices, as well as preparing new kinds of quantum states.'

As well as Oxford and Imperial the collaboration includes researchers from the Max Planck Institut at Erlangen (Germany), and the University of Queensland, Brisbane, (Australia).

Image: Photon waves via Wikimedia Commons. 

Your comments

There are currently no comments on this page.

• Post a comment