Clover leaf by Scott Robinson on Flickr

Quantum mechanics explains efficiency of photosynthesis

Light-gathering macromolecules in plant cells transfer energy by taking advantage of molecular vibrations whose physical descriptions have no equivalents in classical physics, according to the first unambiguous theoretical evidence of quantum effects in photosynthesis published today in the journal Nature Communications. More...

Published: Jan 9, 2014 3:48:33 PM

Free Electron Lasers and Attosecond Light Sources Conference

UCL is hosting a conference on Free Electron Laser and Attosecond-Strong Field Science from June 30 to July 2 2014 at UCL. The preliminary  web-page for the conference is now live at
http://www.ucl.ac.uk/phys/amopp/atto-fel-conference More...

Published: Oct 1, 2013 2:24:13 PM

Macroscopic and microscopic work.

Quantum engines must break down

Our present understanding of thermodynamics is fundamentally incorrect if applied to small systems and needs to be modified, according to new research from University College London (UCL) and the University of Gdańsk. The work establishes new laws in the rapidly emerging field of quantum thermodynamics. More...

Published: Jun 27, 2013 9:40:58 AM

PhD: Production and manipulation of Rydberg positronium states.

One of the biggest mysteries in physics is the apparent absence of antimatter from the universe. Even though the standard model of particle physics tells us that matter and antimatter should have been created in equal amounts after the big bang, there seems to be an imbalance in favour of matter than we cannot explain. In order to try and understand this it is imperative to conduct experiments that test our assumption that matter and antimatter behave in an exactly symmetrical manner. One very basic way of doing this is to check and see if antimatter behaves just like matter in a gravitational field. However, in practise this is not easy to do.

The short lived meta-stable atom positronium (Ps) is made from an electron bound to its antiparticle, the positron. However, matter-antimatter systems are intrinsically unstable and eventually (in less than a microsecond) this hydrogen-like system will self-annihilate, converting the particles into gamma rays. There are many experimental situations in which it would be desirable to produce Ps atoms with longer lifetimes. This may be achieved by creating excited states, in which the electron-positron wavefunctions have negligible overlap, and the annihilation lifetime is effectively infinite. Under these conditions the Ps lifetime will be governed by radiative decays, just as with any other stable atomic system. Thus methods developed for the production of long-lived Rydberg atoms may be applied to the Ps system to produce the required long lived states. In particular, states with maximal angular momentum (known as circular states) have very long lifetimes. This project is based on the application of known methods to produce and manipulate such states to Ps atoms, with the long term aim of measuring the gravitational free-fall of Ps.

The work will be carried out under the supervision of Dr David Cassidy in collaboration with Professor Peter Barker and Dr. Stephen Hogan from UCL. The studentship is available from September for EU or UK nationals and is funded for 3 years.

For further details please contact Dr David Cassidy.