http://www.gizmag.com/two-photon-walk-quantum-computing/16394/

# Monthly Archives: October 2010

## Quantum Interferometric Sensors – talk by Prof Jonathan Dowling

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?)

Filed under Events

## A Visit to the Laser Teaching Center

I stopped by the Laser Teaching Center today, to talk with Dr. Noe. He had sent me two abstracts for two talk’s this week on Quantum Information, which I am planning on attending now. Right now my knowledge on Quantum Information is quite limited and I was explaining how each time I begin to read about it I spend a good deal of time reading about the terminology in general. For example, last week I tried to read a book from the school Library on Quantum computing but after the fourth page realized I needed to learn how to understand Hilbert space. So I put the book down and went off researching Hilbert Space and Bra-Ket notation

The Foundations of Quantum Mechanics class I am taking has been helping quite a lot with providing a guide of what to focus on learning though to begin to understand QM. Which lead to talking about the paper for QM class I am writing about Michael Faraday, which lead to talking about Faraday’s effect within optics.

Dr Noe had a sample of Terbium Gallium Garnet, which is a material that exhibits a very high Faraday effect due to its high Verdet constant. He was also explaining about how a Faraday Isolator is a sort of optical diode, to prevent light of a specified wavelength from reflecting back towards the source.

During my research on Faraday’s Effect for the paper, I remembered how he was unable to observe the effect in water, but Dr Noe was telling me about how it is possible to observe this effect now, by using an optical material to polarize light into darkness and then set a magnetic oscillator to cause the polarization to change slightly, and permit a slight flicker in the darkness of the polarization, enabling one to measure the Verdet Constant of water. Then using a Lock In Amplifier you observe the flicker to isolate the frequency which matches the frequency of the magnetic flicker.

We also talked about how to use complex numbers for a little bit, and how easy it can be to use complex numbers for wave functions. And Dr Noe mentioned how at the Liago experiment, where they are setting off to measure very small shifts in interference patterns between two mirrors a kilometer apart, the principles of Quantum Error Correction, which will be the subject of one of the talks this week, is being applied to achieve more accurate measurements.

Filed under Side Projects

## Radiation & Rutherford

The relation between the sizes of electrons .02 angstroms, Gold Nucleus 10-5 angstroms, and the radius of the atom .5 angstroms.

Very important, we learned about alpha – e^2/4 pi epsilion nought h-bar c, this was called the infinitesimal constant? Didn’t quite catch the name.

So Rutherford was looking at alpha particles, and he was shooting the Helium 4 particles at a thin sheet of gold.

We calculated and equation for knowing the certain number of electrons, which would have their path bent by columbs law and hit at a certain angle of a "ring". To help with this we learned how to calculate solid angles.

Filed under Mod Phy