Quantum interference is one of the most striking features predicted by quantum mechanics. Originally observed with light in the famous double-slit experiment, quantum interference can also affect electrons moving around in nano-scale electronic circuits fabricated in semiconductor devices known as 'single-electron transistors' if there are two competing pathways for the current. Even though electrons are flowing, destructive quantum interference can block the overall current through the device. Now, Prof Andrew Mitchell in UCD School of Physics and his collaborators have shown that combining quantum interference with the natural electrostatic repulsion between electrons can lead them to effectively 'split' into exotic 'Majorana fermion' quasiparticles at a quantum critical point, which may be useful for quantum computing applications. The research was published in Physical Review Letters, the flagship journal of the American Physical Society, and highlighted as an Editors' Suggestion.
New microscopic devices, which leverage the unique and fragile effects of quantum mechanics, need to be delicately manipulated. To operate quantum devices, such as quantum computers or quantum sensors, requires the ability to change from one configuration to another at will. An example of this is moving an electron or atom from one location to another. A recent article published in the prestigious Physical Review Letters, led by UCD's Dr. Anthony Kiely and Dr. Steve Campbell together with collaborators at the University of Strathclyde and Queen's University Belfast, introduces a new mathematical toolkit which determines precisely how this can be done. The technique works by changing the device configuration back and forth so that any unknown imperfections or errors counteract themselves — with the result that they have little detrimental effect.
UCD astrophysicist Dr Antonio Martin-Carrillo has just published a paper in Nature as part of an international team using multiple space and ground-based telescopes, including James Webb Space Telescope, to observe the second brightest gamma-ray burst (about 1,000 times brighter than a typical gamma-ray burst) and identify the neutron star merger that generated an explosion to create it. They were also able to detect the chemical element tellurium in the explosion’s aftermath. While theoretically gamma-ray bursts associated to neutron star mergers last no more than few seconds, this GRB lasted for 200 seconds, placing it firmly in the category of long duration gamma-ray bursts.
The quantum technologies revolution has been driven by the tantalizing prospect of building a universal quantum computer. A major challenge is to manipulate quantum information. A proposed route to fault-tolerant quantum computation exploits the topological properties of so-called 'anyon' particles. Simple Majorana anyons have been predicted to arise in special quantum devices, but are not flexible enough to be used efficiently in quantum computing. More exotic parafermions are the holy-grail of quantum computing, but until now their existence in quantum dot nanoelectronic devices has only be hypothesized. In recent work led by UCD's Dr Andrew Mitchell, and involving theorists from Paris and experimentalists in Stanford University, the existence of parafermions in a real double quantum dot device was demonstrated for the first time. Their proof hinges on the solution of a theoretical model previously thought unsolvable. The work was published in the prestigious Physical Review Letters.
Systems Biology meets Nanoinformatics: in an impressive collaborative work published in Nature Nanotechnology an interdisciplinary team lead by University of Tampere not only discovered common responses to nanoparticles across all kinds of organisms from plants and invertebrates to humans but also common features of nanomaterials triggering those responses. This work provides insights into the molecular mechanisms of toxicity of nanomaterials. UCD School of Physics participated in this effort through Soft Matter Modelling Lab: Dr Konstantinos Kotsis, Dr Ian Rouse, Dr Anais Colibaba and Dr Vladimir Lobaskin by providing in silico materials characterisation data and analysis of bionano interactions.
Some problems are simply too hard to solve on digital computers. In the physical sciences, such problems arise in the field of quantum condensed matter, which seeks to understand the complex behaviour of real materials from the perspective of their fundamental quantum constituents. For example, the mysteries of high-temperature superconductivity may finally be revealed if only we could solve the models describing them. UCD theoretical physicist Dr Andrew Mitchell and his experimental collaborators in Stanford have designed and built an 'analogue' quantum computer that may be able to shed light on such problems by exploiting the advantage gained by using nanoelectronics circuits with quantum components.
Entropy is an important concept in physics, which helps characterize the thermodynamic properties of a system. In quantum nanoelectronics devices that may form the basis for future quantum technologies, the entropy plays a particularly important role. Although studied theoretically for many years, it has not been possible to measure entropy experimentally in such systems. However, UCD physicist Dr Andrew Mitchell and an international team of collaborators have now developed a new technique to measure the entropy of quantum devices, utilizing Maxwell relations to convert measured changes in charge for a quantum process into an entropy change. Their joint theory-experimental work demonstrates the first measurement of the ln(2) entropy of a qubit as well as bit erasure in a many-body system. The work also sheds light on the measurement backaction problem in quantum mechanics. The research was published in Physical Review Letters, the flagship journal of the American Physical Society.
UCD physicists Dr. Vladimir Lobaskin and Dr. Julia Subbotina in a recent Nature Nanotechnology paper from the EU H2020 NanoSolveIT consortium made a contribution to the development of nanoinformatics. Their work presents a novel concept of nanomaterial description, which includes computational evaluation of advanced material properties and environment-dependent characteristics to enable prediction of nanomaterial functionalities from the first principles and in silico screening materials for new applications.
UCD physicists Dr. Vladimir Lobaskin and Dr. Ian Rouse in a recent collaborative work published in Nano Today have studied protein-nanoparticle interactions from the first principles. Their multiscale model of bio-nano interactions allows one to relate the material properties to functionalities such as binding of specific proteins and can be used for testing nanomaterials' safety and suitability for biomedical applications.
In quantum mechanics, fundamental particles can be either fermions or bosons -- an important classification that encodes on a deep level the exchange statistics of those particles and hence controls their observable physical properties. However, a remarkable feature of systems comprising many interacting quantum particles is that collective behaviour can lead to emergent phenomena quite different from that of the individual constituents. In particular, fermions can effectively become "fractionalized" into Majorana fermions or more exotic parafermions that have different exchange statistics. We call these "anyons" since they are neither fermions nor bosons. A smoking-gun signature of such fractional particles is their predicted fractional entropy. An international team of experimental and theoretical physics researchers, including UCD physicist Dr Andrew Mitchell, recently demonstrated for the first time this fractional entropy signature in a quantum nanoelectronics device.
When is the quantum speed limit (QSL) really quantum? While vanishing QSL times often indicate emergent classical behavior, it is still not entirely understood what precise aspects of classicality are at the origin of this dynamical feature. New research involving UCD Theoretical Physics Dr. Steve Campbell demonstrates that vanishing QSL times (or, equivalently, diverging quantum speeds) can be traced back to reduced uncertainty in quantum observables and can thus be understood as a consequence of emerging classicality for these particular observables. The findings are published in the new high impact open access APS journal PRX-Quantum.
New research lead by UCD Theoretical Physicist Dr Andrew Mitchell has revisited non-Fermi liquid physics in quantum dots and indicates the presence of a possibly observable Majorana fermion at a symmetry point. The findings were published as an "Editor's Suggestion" in the prestigious APS Physical Review Letters.
A new result released by the CMS Collaboration presents evidence of the Higgs boson interacting with the muon. Members of the School of Physics at UCD were responsible for the high-level trigger system to record the data analysed.
New research from the group of UCD Theoretical Physicist Dr Andrew Mitchell shows that the famous 'Mott' metal-insulator transition in materials science is in fact related to deep concepts in quantum topology. The findings were published as an "Editor's Suggestion" in the APS Physical Review.
Prof. Martin Grunewald of UCD School of Physics has been involved with the observation of coupling between the Higgs boson and the bottom quark at the CMS experiment in CERN. The observation represents yet another important milestone reached in the scrutiny of the Higgs boson and its interactions with Standard Model particles.
An international team of more than 200 astronomers from 18 countries, including researchers from University College Dublin (UCD), has today published the first phase of a major new sky survey at unprecedented sensitivity using the Low Frequency Array (LOFAR) telescope.
Associate Prof. Brian Vohnsen of UCD School of Physics and his team have developed a Hartmann–Shack wavefront sensor that employs a digital micromirror device in combination with a single lens for serial sampling by scanning. The research is part of an H2020 ITN on Myopia Research.
An international team of astronomers, including UCD physicist Dr Morgan Fraser, have managed to catch the first flash of light from an exploding star. The team used the four-meter Blanco telescope in Chile to repeatedly scan a small region of the sky, and managed to detect a handful of stars in distant galaxies at the moment they exploded as supernovae. The research is published in Nature Astronomy.
The VERITAS collaboration, including UCD School of Physics members Assoc. Prof. John Quinn and Ph.D. student Ste O'Brien, has confirmed the detection of very-high- energy gamma-ray emission from the vicinity of a supermassive black hole, observations prompted by the detection of a spatially coincident high-energy neutrino event by the IceCube collaboration. This black hole is potentially the first known astrophysical source of high-energy cosmic neutrinos, a type of ghostly subatomic particle, and the observations represent a breakthrough in multi- messenger astrophysics.
For the first time, an international team of astronomers including Dr. Morgan Fraser from the School of Physics at University College Dublin, have directly imaged the formation and expansion of a fast-moving jet of material ejected when the powerful gravity of a supermassive black hole ripped apart a star that wandered too close to the cosmic monster. The new findings have been published in a paper in the prestigious international journal Science, led by Prof. Seppo Mattila of the University of Turku in Finland and Dr. Miguel Pérez-Torres from the Institudo de Astrofisica de Andalucia in Spain.
UCD theoretical physicist Dr Andrew Mitchell has published new research in the journal 'Science' on fascinating quantum mechanical effects in nanoelectronic circuits. The paper uncovers aspects of exotic 'quantum phase transitions', with state-of-the-art experimental results from collaborators in Paris matching beautifully with calculations from the theoretical nanoelectronics group in UCD.
Associate Prof. Dominic Zerulla of UCD School of Physics has uncovered the dynamics of radial deformation recovery processes in single-wall carbon nanotubes, in new research published in the journal 'Carbon'.
Prof. Martin Grunewald of UCD School of Physics has been involved with the observation of top-antitop-Higgs production at the CMS experiment in CERN. In addition to comprising the first observation of a new Higgs boson production mechanism, this measurement establishes the tree-level coupling of the Higgs boson to the top quark, and hence to an up-type quark, and is another milestone towards the measurement of the Higgs boson coupling to fermions.
Associate Prof. Brian Vohnsen of UCD School of Physics confirms a clear link between the Stiles-Crawford effect directionality, uncorrected defocus, and axial eye length. This may play a role for emmetropization and thus myopic progression as cone photoreceptors capture light from a wider pupil area in elongated eyes due to a geometrical scaling.
Associate Prof. Vladimir Lobaskin and Aleksei Kabedev of UCD School of Physics study the mechanics of endothelial glycocalyx, the protective polymer brush in our blood vessels, using computer-simulated atomic force microscopy (AFM) experiments, obtaining new insights into its functionality.
Dr Andrew Mitchell of UCD School of Physics has published a paper in Nature Communications on quantum effects and strong correlation phenomena in molecular electronics, and proposed applications for a new generation of quantum interference effect transistors.
Associate Prof. Dominic Zerulla of UCD School of Physics presents an optimal solution to the problem of broadband solar havesting in nanostructured plasmonic materials, that significantly improves the efficiency of solid state solar cells.
Associate Prof. Brian Vohnsen of UCD School of Physics investigates vision through the natural eye pupil by using a new geometrical optics model to calculate the fraction of overlap between light at the retina and the photoreceptor outer segments where absorption triggers vision.
