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Efficiently simulating many-body localisation

14 October 2016

Dr Zlatko Papic's paper has just been published in Physical Review Letters.

The amount of quantum entanglement in a many-body wave function determines whether it can be efficiently compressed and encoded by a small number of classical parameters. Ground states of many-body systems are known to have low entanglement, and can be efficiently simulated by the so-called "matrix product states" -- the property which underlies the success of the density-matrix renormalisation group.

In this Letter, we characterise the entanglement of highly excited states in many-body localised (MBL) systems by studying its "entanglement spectrum". MBL phases have been a subject of much recent interest as phases of matter that break ergodicity and thus avoid thermalisation. We argue that the entanglement structure of MBL states, while different from ground states, still allows for compact parametrisation by matrix product states. We develop an efficient algorithm to obtain highly excited states of large MBL systems. This work opens a door for studying a broad class of disordered quantum systems, inaccessible by other techniques. We expect that the new algorithm will also give a much-needed insight into the nature of the transition between MBL and ergodic (thermal) phases.

Read the full article here: http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.160601




PHOTON16 Conference

22 September 2016

The University of Leeds hosted the largest Optics and Photonics conference in the UK. PHOTON16 is the eighth in a series of biennial conferences that started in 2002. This year, we welcomed more than 400 participants from 26 countries.

Scientific sessions were complemented by a technical exhibition with 37 companies presenting their products. We were especially pleased to welcome seven world renowned plenary speakers to the conference.

The PHOTON series brings together wide areas of light related science and technology that represent the strength and breadth of activity in the UK and elsewhere in the world. Our scientific presentations encompassed the classical and quantum nature of light and covered applications ranging from bio-photonics, through metrology to ultrafast optics.

During the conference, several honours and prizes were announced. For example our very own Helen Gleeson (Head of the School of Physics and Astronomy in Leeds) was invited to present the Rank Prize Funds Lecture (see picture).

This PHOTON conference was organised on behalf of the Institute of Physics, especially the Optical Group, the Quantum Electronics and Photonics (QEP) Group, the Quantum Optics, Quantum Information and Quantum Control (QQQ) Group, the Instrument Science and Technology (ISAT) Group, the Computational Physics Group and the Environmental Physics Group. Our current programme builds upon a long history of meetings and conferences organised by the groups. These stretch long before the first PHOTON conference, which was held in Cardiff in 2002.

More information can be found at www.photon.org.uk/home.




Work Experience Week

6 July 2016

The School recently hosted a Work Experience Week where 20 Year 12 students experienced what it is like to work in a research-intensive university

With so many requests from students seeking work experience throughout the year, the School of Physics and Astronomy dedicated a full week for twenty Year 12 students to join us and learn what it’s like to work in a research-intensive university. 

Throughout the inaugural work experience week from 18 to 22 July,  the Year 12 students experienced the inside workings of the School of Physics and Astronomy, meeting with academics and current postgraduate students to learn about their research carried out within the School.    

The purpose of the Work Experience Week was for our participants to gain skills in research, problem solving and collaborative group work - all within a real, working academic setting.  On Friday 22 July, they presented their own conference-style research posters to their peers, external guests, staff and students at our Showcase Event.     

To learn more about the Work Experience Week and next year’s application information, please visit www.physics.leeds.ac.uk/workexperience.      




Study reveals low density water structure in a cryoprotectant matrix

29 April 2016

Scientists from the School of Physics and Astronomy have determined the impact of cryoprotectant molecules on water, and gained access to the structure of water at temperatures far below zero degrees Celsius. The study was highlighted on the cover of The Journal of Physical Chemistry B, with cover art designed by Leeds Physics undergraduate Jamie Ridley.

 

Leeds physicists Dr Lorna Dougan and Dr James Towey showed that when the cryoprotectant molecule glycerol was mixed with water, the molecules nanosegregated into a mesh or 'or sponge' that locked small clusters of water molecules into pockets. They then cooled the mixture down to 238 K and found that these water clusters persisted. In normal freezing, water molecules link up to form ice crystals, however in the cryoprotectant mesh the water molecules remained liquid.  The study revealed that in this matrix the water forms a low density structure which is protected by an extensive and encapsulating glycerol interface.

The paper can be found here: http://pubs.acs.org/doi/abs/10.1021/acs.jpcb.6b01185


The study was supported by the Engineering Physical Sciences Research Council, through a PhD studentship to Dr James Towey, and the European Research Council, through a fellowship to Dr Lorna Dougan.




International Women's Day in Physics

14 March 2016

International Women’s Day recently took place across the world; a day to recognise women and their achievements in all fields. In Physics and Astronomy we celebrated by hosting an informal afternoon tea session, fuelled by discussions around Women in Science and each person’s journey to where they are now and how gender has impacted that

Professor Julia Yeomans FRS from the University of Oxford was our guest for the session and spoke about her experiences throughout her career, it generated some fascinating discussions and was a great opportunity for all women in the school, ranging from academics to administrators to look at how gender has impacted their career, both positively and negatively.

In addition to this, Professor Yeomans was also the speaker at the Stoner Colloquium, where she discussed ‘Nature’s Engines; Powering Life’, an inspiring talk about active matter.

Information about Stoner Colloquia is here.




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