Quantum Interferometric Sensors – talk by Prof Jonathan Dowling

Published on: Wed Oct 20 2010

The talk began with a diagram, of three overlapping circles, Quantum Information, Quantum Computing and Quantum Imaging. Sitting in the overlapping point of the three circles was where we were going to be for this talk, and the whole diagram made up a large outer circle Quantum Metrology. (I thought that is the science of predicting the weather?)

At first the speaker was talking about funding for Quantum computing and how it has started to decrease as the focus narrows, meaning at first there were all sorts of ideas but now that there is a better idea of what works, the focus and funding has narrowed. He talked about the idea's which have seen a decrease, and one of them what Single photon circuits, which was quite startling to me. He also said they (DARPA?) are aiming for 2020 hardware for quantum computing.

Then a bit about a quantum internet, and how Quantum repeaters would be needed to see this happen...

In general though the point seemed to be that by using ideas fro Quantum computing and Quantum Imaging it is possible to build better measuring devices, which do not suffer from as much loss. There is quite a lot to understand. Things to read about:

- Parity measurement (Is this Modulo?)
- exp ( ) Notation
- an exponent that looks like a small cross
- Optical Tables
- Post Selection
- Kerr Material
- "Projective measurements yields effective Kerr"
- Ancillas
- Vortex
- OAM Beam (did I hear this right?)