The University of Southampton
Telephone:
+442380592076
Email:
a.obannon@soton.ac.uk

Dr Andy O'bannon 

Head of the Equality, Diversity, and Inclusion Committee for Physics and Astronomy

Work history

2015-present: Royal Society University Research Fellow and Senior Researcher, STAG Research Centre, University of Southampton

2013-15: Royal Society University Research Fellow, University of Oxford

2010-13: Research Associate (postdoc), DAMTP, University of Cambridge

2008-10: Research Fellow (postdoc), Max Planck Institute for Physics, Munich

2002-08: M.S. and Ph.D. in Physics, University of Washington, Seattle. Advisor: Prof. Andreas Karch.

2002-07: Jack Kent Cooke Graduate Scholar (full funding for graduate studies)

1998-2002: B.A. in Physics and the Writing Seminars, the Johns Hopkins University

Qualifications

BA Physics and the Writing Seminars, Johns Hopkins University (1998-2002)

PhD, University of Washington, Seattle (2002-2008, Advisor: Prof. Andreas Karch)

Research Fellow, Max Planck Institute for Physics, Munich, Germany (2008-10)

Research Associate, DAMTP, University of Cambridge (2010-13)

Royal Society University Research Fellow, University of Oxford (2013-15) and University of Southampton (2015-present)

Research

Research interests

My research is focused on strongly-interacting systems with unusual transport properties. An example from particle physics is the quark-gluon plasma, the hot soup of quarks an gluons that existed micro-seconds after the Big Bang, and is reproduced. The quark-gluon plasma has a shear viscosity lower than any other known fluid. An example from condensed matter physics are the ``strange metal’’ states of heavy fermion compounds and high-temperature superconductors. These materials have an electrical resistivity scaling as the square of temperature, unlike the linear scaling of most metals. Few reliable techniques exist to study such systems. As a result, the origins of their unusual properties remain mysterious.

To study such systems, I use a novel technique, discovered in string theory, called holography. Holography is the statement that certain strongly-interacting systems are equivalent, in a precise mathematical sense, to Einstein’s theory of gravity in one higher dimension. In other words, by calculating things in Einstein’s theory of gravity, we can learn about the quark-gluon plasma, strange metals, and more!

To be clear, the systems involved in holography are purely theoretical, and do not describe any particular real system. However, they have the potential to reveal general principles applicable to real systems. In other words, holography provides “toy models” that may reveal patterns characteristic of strongly-interacting systems. Indeed, holography already has a success story: all fluids described by holography have the same ratio of shear viscosity to entropy density, of roughly 0.1. That value is shockingly close to the value estimated for the quark-gluon plasma, which is also roughly 0.1. Holography thus revealed a general principle: a ratio of shear viscosity to entropy density of roughly 0.1 is characteristic of strongly-interacting fluids.

The goal of my research is to find similar ``universal’’ properties. Indeed, with various collaborators I have discovered substantial evidence for generic, if not completely universal, properties of the electrical resistivity, impurity physics, entanglement, and more in many holographic systems. Above all, I have learned that holography and string theory have much to teach us about strongly-interacting systems!

Teaching

Module Coordinator for Final Year Synoptic Physics PHYS3017 and PHYS6015

Publications

Jensen, Kristan and O'Bannon, Andy (2016) Constraint on defect and boundary renormalization group flows. Physical Review Letters, 116 (91601), 1-5. (doi:10.1103/PhysRevLett.116.091601).

Estes, John, Jensen, Kristan, O'Bannon, Andy, Tsatis, Efstratios and Wrase, Timm (2014) On holographic defect entropy. Journal of High Energy Physics, 2014 (84), 1-47. (doi:10.1007/JHEP05(2014)084).

Erdmenger, Johanna, Hoyos, Carlos, O'Bannon, Andrew, Papadimitriou, Ioannis, Probst, Jonas and Wu, Jackson (2017) Two-Point Functions in a Holographic Kondo Model. Journal of High Energy Physics, 2017 (3), [39]. (doi:10.1007/JHEP03(2017)039).

O'bannon, Andrew, Probst, Jonas and Papadimitriou, Ioannis (2016) A holographic two-impurity kondo model. Journal of High Energy Physics, 2016 (103), [103]. (doi:10.1007/JHEP01(2016)103).

Erdmenger, Johanna, Flory, Mario, Hoyos, Carlos, Newrzella, Max-Niklas, O'Bannon, Andrew and Wu, Jackson M.S. (2016) Holographic impurities and Kondo effect. Fortschritte der Physik, 64 (4-5), 322-329. (doi:10.1002/prop.201500079).

Erdmenger, Johanna, Hoyos, Carlos, O'Bannon, Andrew, Papadimitriou, Ioannis, Probst, Jonas and Wu, Jackson M.S. (2017) Holographic Kondo and Fano resonances. Physical Review D, 96 (2), [021901]. (doi:10.1103/PhysRevD.96.021901).

O'Bannon, Andrew, Probst, Jonas, Rodgers, Ronald, James and Uhlemann, Christoph F. (2017) A first law of entanglement rates from holography. Physical Review D, 96, [066028]. (doi:10.1103/PhysRevD.96.066028).

Gushterov, Nikola I., O'Bannon, Andrew and Rodgers, Ronald (2017) On holographic entanglement density. Journal of High Energy Physics, 2017 (10), [137]. (doi:10.1007/JHEP10(2017)137).

Gushterov, Nikola I., O’Bannon, Andy and Rodgers, Ronnie (2018) Holographic zero sound from spacetime-filling branes. Journal of High Energy Physics, 2018 (76), 1-57. (doi:10.1007/JHEP10(2018)076).

Jensen, Kristan, O'Bannon, Andrew, Robinson, Brandon and Rodgers, Ronald, James (2019) From the Weyl anomaly to entropy of two-dimensional boundaries and defects. Physical Review Letters, 122, [241602]. (doi:10.1103/PhysRevLett.122.241602).

Estes, John, Krym, Darya, O'Bannon, Andrew, Robinson, Brandon and Rodgers, Ronnie (2019) Wilson surface central charge from holographic entanglement entropy. Journal of High Energy Physics, 2019 (32), 1-52. (doi:10.1007/JHEP05(2019)032).

Evans, Nicholas, O'bannon, Andrew and Rodgers, Ronald, James (2020) Holographic Wilson lines as screened impurities. Journal of High Energy Physics, [188]. (doi:10.1007/JHEP03(2020)188).

O'bannon, Andrew, Robinson, Brandon J, Chalabi, Adam and Sisti, Jacopo (2020) Central charges of 2d superconformal defects. Journal of High Energy Physics. (doi:10.1007/JHEP05(2020)095).

Contact

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