Student satisfaction in Physics and Astronomy at the University of Southampton continues to increase according to the latest 2015 National Student Survey (NSS) results.

Overall student satisfaction now stands at 97 per cent, a rise of three percentage points from 2014 and an increase of 12 percentage points since 2013. Feedback and assessment has also seen a large increase with an exemplary 83 percent score.

Among MPhys Physics and Astronomy students, 100 percent expressed their satisfaction with the quality of their course.

This outstanding performance exceeds University and sector results, placing us 5th among UK physics departments and top within the Russell Group. Professor Jonathan Flynn, Head of Physics and Astronomy, said: “We are delighted to have achieved such excellent NSS results. This is recognition of our continual course development over recent years and our efforts to listen and respond to our students’ opinions and feedback. It shows that our students are increasingly satisfied with the quality of their learning experience. We do not want to rest on success, however, and will continue our efforts and dialogue with our students to help them make the most of their time at university.â€?

The National Student Survey has been conducted annually since 2005 by HEFCE and IpsosMori and asks final year undergraduates for feedback on their universities and courses. Core questions in the survey cover the student learning experience including: teaching on my course; assessment and feedback; academic support; organisation and management; learning resources; personal development; students’ union and overall satisfaction.

An international team of scientists, including Dr Luca Sapienza from the University of Southampton, have developed a new technique for finding quantum dots.

A quantum dot should produce one and only one photon—the smallest constituent of light—each time it is energized, and this characteristic makes it attractive for use in various quantum technologies, such as secure communications. However, the trick is in finding them.

While they appear randomly, in order for the dots to be useful they need to be located in a precise relation to some other photonic structure, be it a grating, resonator or waveguide, which will enable control of the photons that the quantum dot generates. However, finding the quantum dots—they’re just about 10 nanometers across—is no small feat.

Now, researchers working at the National Institute of Standards and Technology (NIST) in the United States, in collaboration with the universities of Southampton (UK)and Rochester (US), have developed a simple new technique for locating them and used it to create high-performance single photon sources.

This new development, which is published in Nature Communications, may make the manufacture of high-performance photonic devices using quantum dots much more efficient. Such devices are usually made in regular arrays using standard nanofabrication techniques like electron-beam lithography and semiconductor etching. However because of the random distribution of the dots, only a small percentage of them will line up correctly, at the optimum position within the device. This overall process thus produces very few working devices.

“This is a first step towards providing accurate location information for the manufacture of high performance quantum dot devices,â€? says NIST physicist Kartik Srinivasan. “So far, the general approach has been statistical - make a lot of devices and end up with a small fraction that work - but our camera-based imaging technique instead seeks to map the location of the quantum dots first, and then uses that knowledge to build optimized light-control devices in the right place.â€?

Dr Luca Sapienza, from the University's Quantum Light and Matter group, says: “This new technique is sort of a twist on a red-eye reducing camera flash, where the first flash causes the subject’s pupils to close and the second illuminates the scene.â€?

In their setup, instead of xenon-powered flash the team used two LEDS. One LED activates the quantum dots when it flashes (you could say this LED gives the quantum dots red eye). At the same time, a second, different color LED flash illuminates metallic orientation marks placed on the surface of the semiconductor wafer the dots are embedded in. Then a sensitive camera snaps a 100-micrometer by 100-micrometer picture.

By cross-referencing the glowing dots with the orientation marks, the researchers can determine the dots’ locations with an uncertainty of less than 30 nanometers. Their coordinates in hand, scientists can then tell the computer-controlled electron beam lithography tool to place any structure the application calls for in its proper relation to the quantum dots, resulting in many more usable devices.

Using this technique, the researchers demonstrated grating-based single photon sources in which they were able to collect 50 per cent of the quantum dot’s emitted photons, the theoretical limit for this type of structure. They also demonstrated that more than 99 per cent of the light produced from their source came out as single photons. Such high purity is partly due to the fact that the location technique helps the researchers to quickly survey the wafer (10,000 square micrometers at a time) to find regions where the quantum dot density is especially low–only about one per 1,000 square micrometers. This makes it far more likely that each grating device contains one—and only one—quantum dot.

This work was performed in part at NIST’s Center for Nanoscale Science and Technology(CNST), a national user facility available to researchers from industry, academia and government.

Researchers from the University of Southampton have demonstrated for the first time a new laser cooling method, based upon the interference of matter waves, that could be used to cool molecules.

Our ability to produce samples of ultra-cold atoms has revolutionised experimental atomic physics, giving us devices from atomic clocks (the core of GPS) and enabling a range of quantum devices, including the possibility of a quantum computer.

However, the current technique of cooling atoms down from room temperature to the ultra-cold regime using optical molasses (the preferential scattering of laser photons from a particle in motion which leads to slowing) is limited to atoms with favourable electronic structure. As a result, only a small fraction of atomic elements, along with a select few diatomic molecules, have been cooled in this manner.

Writing in Physical Review Letters, the research team at Southampton has provided the first proof-of-principle demonstration of a new laser cooling technique, based on a proposal by Martin Weitz and Nobel laureate Ted Hänsch in 2000, which is in principle applicable to atoms and molecules as yet untamed by conventional laser cooling.

Using the new approach, which harnesses the quantum interference of matter waves, the team was able to cool a sample of already-cold Rubidium down close to the fundamental temperature limit of laser cooling.

The cooling technique is based on matter wave interferometry, in which an atom (the matter wave) is placed into a superposition of states by a laser pulse. The atom travels simultaneously along two paths, which interfere at a later time, and the impulse imparted to the atom depends on the difference between these paths. The same phenomenon can be used to engineer an extremely sensitive metrological device.

Fundamentally, the impulse depends upon how the difference in energy along the two paths compares with the energy of the laser photons, where the atom’s energy is formed of potential (internal electron configuration) and kinetic (external motion) parts.

The clever trick behind Weitz and Hänsch’s scheme is to make the laser interact with the atoms in such a manner as to remove the dependence on the potential energy, and thus the internal electronic structure, leaving the interference based solely on the kinetic energy of the particle.

The team at Southampton has demonstrated the principle of using matter wave interference to cool atoms. Their results are a significant step toward decoupling the cooling mechanism from the internal electronic structure – the 'Holy Grail' of general molecular laser cooling.

Dr Alex Dunning, from Physics and Astronomy at the University of Southampton and lead author of the study, said: “There is a great push to extend ultra-cold physics to the rest of the periodic table to explore a greater wealth of fundamental processes and develop new technologies and we hope that our demonstration will help.

“While other cooling techniques can be effective they are limited to certain species and often require a multitude of lasers. Our technique, should we succeed in extending it to Weitz and Hänsch’s complete scheme, would be sort of a catch-all; progress so far in cooling molecules tends to use the details of specific molecules, rather than being something general; that's why this is exciting, even though our actual experiment just uses atoms.â€?

Group leader, Dr Tim Freegarde, said: “These beautiful results have demonstrated that the method is feasible and can result in colder atoms than conventional Doppler cooling. To move on to other atoms and molecules will require more powerful lasers with shorter pulses, of the type used in coherent control chemistry, so the future of this method is very promising.â€?

A Southampton astronomer is among a team of international researchers whose work has revealed a surprising similarity between the way in which astronomical objects including black holes, white dwarfs and young stars grow.

Christian Knigge, Professor in Physics and Astronomy at the University of Southampton, worked with colleagues from around the world to study one of the most important, but least understood processes in astronomy – accretion, where the mass of an object grows by gravitationally collecting material from nearby.

The article Accretion-induced variability links young stellar objects, white dwarfs, and black holes has been published in the latest edition of Science Advances – an international journal that publishes significant, innovative, original research that advances the frontiers of science.

The paper reveals a close relationship between the way in which different types of accreting objects vary in brightness over time. Their result connects proto-stars resembling our Sun at the tie of its birth, to accreting white dwarfs, to supermassive black holes with a billion times the mass of the Sun, located in galaxies millions of light years away.

The team found that the two most important properties of the object are its physical size scale and the rate at which it is accreting matter. They discuss a unified scenario for understanding brightness variations from accretion disks around different types of stars and compact objects. Previous work had unified the variability in disks around black holes of different mass ranges, but by considering not just the mass of the object but also its size, scientists can now add accreting white dwarfs and proto-stars to this unified picture.

The research saw Christian working with two former University of Southampton colleagues. The paper’s lead author, Simone Scaringi, a Humboldt Research Fellow at the Max Planck Institute for Extraterrestrial Physics, in Germany, was an undergraduate, postgraduate and PhD student at the University of Southampton. Tom Maccarone, an Associate Professor in the Department of Physics at Texas Tech University, was a Reader in Astronomy at the University of Southampton.

Christian said: “This is a really exciting result. It suggests that the process by which astronomical objects grow is fundamentally the same, regardless of the type, mass or size of the object.â€?

To find out more and to read the paper in full click here.

The Nobel Prize in Physics for 2015 has been awarded to Takaaki Kajita (University of Tokyo, Japan) and to Arthur B. McDonald (Queen’s University, Canada) ‘for the discovery of neutrino oscillations, which shows that neutrinos have mass’ and for ‘key contributions to the experiments which demonstrated that neutrinos change identities’ (Nobel, 2015).

Takaaki Kajita is collaborator and the scientist in charge of the University of Tokyo node of the European Innovative Training Network (ITN) ‘Invisibles: Neutrinos, Dark Matter and Dark Energy’, which has neutrino oscillations as one of its major research lines. This network comprises 29 nodes, including an active sub-group in Physics and Astronomy at the University of Southampton. The Southampton node is led by Professor Steve King and assisted by Dr Pasquale Di Bari, both of whom are experts in neutrino physics. The ‘Invisibles’ network has recently been awarded substantial additional EU RISE H2020 funding for international networking activities, called ‘Invisibles Plus’. The Southampton node of this project will also be led by Professor King.

In 1998 Takaaki Kajita presented to the world the discovery that neutrinos produced in the atmosphere switch between two identities on their way to Earth. Arthur McDonald subsequently led the Canadian collaboration which demonstrated that neutrinos from the sun do not disappear on their way to Earth, but change identity by the time of arrival to the SNO detector. The Nobel Prize for 2015 states that, ‘the discovery has changed our understanding of the innermost workings of matter and can prove crucial to our view of the universe.’

The Southampton node of the ‘Invisibles’ includes Professor Steve King (Scientist in charge), Dr Pasquale Di Bari (Reader in Physics), Thomas Neder (Invisibles ESR), Dr Ivo de Medeiros Varzielas (Marie Curie Fellow), Dr Patrick Ludl (Postdoctoral Research Assistant), Fredrik Bjorkeroth (PhD student), Maria Dimou (PhD student), Andrew Meadowcroft (PhD student), Miguel Crispim Romao (PhD student) and Nick Prouse (NExT PhD student). In addition to the above, ‘Invisibles Plus’ includes Professor Christopher Sachrajda, Professor Jonathan Flynn, Professor Alexander Belyaev, Professor Stefano Moretti, Professor Konstantinos Skenderis and Professor Marika Taylor .