Positrons are the antimatter version of electrons and so their fate in a matter world is ultimately to annihilate. However, prior to this, a positron may combine with an electron to form a matter-antimatter hybrid called positronium. This is akin to a hydrogen atom with the proton replaced by a positron. Fundamental to our understanding of the physical universe, positron and positronium are these days also acknowledged as being fantastically useful in practical applications such as probing material properties and medical diagnostics. However, there is still much that we do not know for sure about the details of the interactions of these particles with ordinary matter. For example if, in a collision with an atom or molecule, a positron captures an electron, in which directions is the positronium likely to travel and with what probability? More...
Published: Jun 17, 2015 12:35:19 PM
How light of different colours is absorbed by carbon dioxide (CO2) can now be accurately predicted using new calculations developed by a UCL-led team of scientists. This will help climate scientists studying Earth’s greenhouse gas emissions to better interpret data collected from satellites and ground stations measuring CO2. More...
Published: Jun 15, 2015 10:29:10 AM
New research from UCL has uncovered additional second laws of thermodynamics which complement the ordinary second law of thermodynamics, one of the most fundamental laws of nature. These new second laws are generally not noticeable except on very small scales, at which point, they become increasingly important. More...
Published: Feb 10, 2015 11:55:53 AM
Dr Alessio Serafini
I work in the quantum information group, with other decent chaps like Sougato Bose and Dan Browne.
My main research activity is centred on the sub-field of "continuous variable" quantum information; that is, essentially, on the study of quantum information in systems with infinite-dimensional Hilbert spaces. As you may guess, such an infinity has a way of making theoretical questions rather messy pretty soon.
Yet, fortunately, questions about continuous variable systems can be tackled for a restricted set of states ("Gaussian states"), which retains considerable interest.
The reason why we care about Gaussian states is that they are relatively easy to generate and manipulate in the lab, while still allowing for the realisation of several non-trivial quantum protocols (such as quantum teleportation, dense coding and key distribution) in a variety of physical systems (quantum light, atomic clouds, cold atoms and Josephson junctions to mention a few).
For Gaussian states, many questions which are extremely difficult in the general setting become treatable analytically (even if, as a cave at, one should stress that when entanglement is involved such questions are seldom trivial, even restricting to Gaussian states).
This is all good, as there are many problems still there to be tackled with reasonable means, with the added value that, every now and again, one might even manage to make statements about more general settings, beyond the Gaussian restriction.
Ah, I also co-lecture, with Prof. Jonathan Tennyson, the Maths III course (PHAS2246) for undergraduate students.
Starting from next year, you should find the course material on this webpage (currently on Prof. Tennyson's page at http://www.tampa.phys.ucl.ac.uk/jonny/2246/index.html).
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