Previous Colloquia
We organise a number of colloquia with guest speakers from UK and International Research Groups. This page contains a list of speakers in recent years. For the current list of colloquia please see our Physics Colloquia page.
We organises a number of colloquia with guest speakers from UK and International Physics and Engineering Departments. For a list of recent speakers please see our colloquia archive page. If you have suggestions for future speakers please contact the local organiser, Dr Erika Andersson.
Previous Colloquia 2015
Wednesday 27th May 2015 DB1.14 at 2.30pm
Dr Johannes Courtial, Glasgow University - Pixellated imaging: from generalised lenses to cloaks
I will talk about the possibilities pixellated ray optics offers for geometrical imaging. These possibilities include generalised lenses and large-scale, but pixellated, transformation-optics devices. We believe that the latter can be realised on length scales so much larger than conventional transformation-optics devices that they will lead to completely new applications.
But what on earth is pixellated ray optics? Much of standard ray optics is informed by theorems derived for globally continuous wave fronts. This limits the properties of the resulting light-ray fields, which are wave-front normals. Our group has pioneered a systematic exploration of an extension of ray optics, pixellated ray optics, which specifically allows wave fronts to be piecewise continuous and which is therefore not limited by theorems derived for globally continuous wave fronts. The wave-front pieces result from transmission through pixellated optical devices. If the wave-front pieces are small (but not so small that diffraction dominates - note that pixellated ray optics is, in general, different from diffractive optics), this pixellation can be as unnoticeable as in a computer monitor. The vision of our work is that, by replacing globally continuous wave fronts with piecewise continuous wave fronts, the possibilities offered by optics, specifically ray optics, can be significantly extended.
Wednesday 13th May 2015 DB1.14 at 2.30pm
Professor Sheila Rowan, University of Glasgow - Gravitational wave searches - status, and future technology developments
A global network of gravitational wave detectors is in now reaching the final stages of construction, with first data expected in 2015.The information carried by these signals will give us new insight into the hearts of some of the most violent events in the Cosmos – from black holes to the beginning of the Universe.The nature of gravitational waves, how the detectors work and what the data from the detectors can tell us about the Universe we inhabit will be discussed.
Wednesday 6th May 2015 DB1.14 at 2.30pm
Dr Fabio Biancalana, Heriot-Watt University - Linear and nonlinear optics of graphene: the mysterious Dirac electrons
In this talk I review the main electronic and optical properties of graphene, a 2D carbon-based material which shows interesting an unconventional behaviour when illuminated by light pulses. In particular, I will review the current status of nonlinear optical phenomena and the most advanced theoretical models to describe light-matter interaction between photons and Dirac electrons in 2D media.
Wednesday 29h April 2015 DB1.14 at 2.30pm
Dr David Petrosyan, Foundation for Research and Technology, Heraklion, Crete - Correlations of Rydberg excitations in optically-driven atomic ensembles
I will discuss resonant optical excitation of Rydberg states of atoms in the presence of relaxations. Atoms in high-lying Rydberg states strongly interact with each other via long-range potentials.These interactions translate into the level shifts of multiple Rydberg excitations which are therefore strongly suppressed. Collection of atoms within a certain "blockade" volume can then accommodate at most a single Rydberg excitation. Perhaps counterintuitively, dephasing of tomic polarization increases the steady-state excitation probability of such a Rydberg "superatom". arger atomic ensembles can accommodate more Rydberg excitations which effectively repel each other. The Rydberg superatoms behave as soft spheres resulting in highly sub-Poissonian robability distribution of the number of excitations. In the finite size one- and two-dimensional systems, the boundary effects mediate quasi-crystallization of Rydberg excitations, while the density-density correlations exhibit damped spatial oscillations. Similarly to a single superatom, dephasing and larger atom density lead to stronger density-density correlations of Rydberg excitations.
Wednesday 22nd April 2015 DB 1.14 at 2.30pm
Professor Amalia Patane, The University of Nottingham - New routes to two-dimensional science and technologies
The development of van der Waals structures made by stacking two-dimensional (2D) crystals has led to the discovery of physical phenomena of fundamental and technological interest. This seminar will review my research at Nottingham on a new class of 2D metal chalcogenide layered compounds suitable for versatile band-gap engineering. From the growth and fabrication of new structures to the demonstration of prototype devices, I will discuss how these layers can provide a platform for scientific investigations and new routes to 2D electronics and optoelectronics.
Thursday 19th March 2015 EM2.33 at 10.15am
Professor Craig Arnold, Princeton University, arranged by Andy Rutherford - Ultrahigh speed z-scanning optics for 3-D and high depth of field imaging and processing
The ability to rapidly change the focal plane of an optical system or rapidly change the intensity distribution in a given focal plane has many important applications in real-world systems ranging from high powered laser processing to detailed high-resolution microscopy. For all these practical uses, a fast, tunable focus element with a low distortion and high transmission coefficient is necessary yet few viable systems exist. Here we present an overview of the existing technologies to achieve highspeed z-scanning in optical beam delivery systems. Benefits and disadvantages of the different technologies will be discussed with particular emphasis on the tunable acoustic gradient index of refraction (TAG) Lens. The TAG lens is capable of varying focal length with sub-microsecond temporal resolution and is fast enough to create an effective line-focus without sacrificing optical power. Fundamental characterization of the TAG lens is presented including the performance metrics such as scanning speed, wavefront aberration, and optical throughput. Finally, recent application examples in laser processing, advanced microscopy, and machine vision for process control will be discussed.
Wednesday 11th March 2015 DB1.15 at 12:15pm
Dr Eleni Diamanti, ParisTech - Quantum cryptography using practical photonic systems
In future quantum information networks, where individual parties will have the ability to communicate in a variety of ways with trusted and untrusted parties, several cryptographic protocols, inherently linked to fundamental features of quantum mechanics, will become essential. Here, we are interested in protocols that are at the heart of many advanced secure communication tasks, namely key distribution and coin flipping. We examine the implementation of these protocols using photonic systems, which provide an ideal physical support for quantum communications. We discuss how imperfections and limitations of practical systems affect the security of the protocols and how implementations offering high performance and strong security guarantees – superior to what classical communication alone could ever provide – are nevertheless achieved. These results, together with perspectives for novel integrated photonic components, offer a powerful toolbox for practical applications of secure quantum communications.
Wednesday 4th March 2015 DB1.14 at 2.30pm
Professor Jason Smith, University of Oxford - Optical microcavities for engineering the light-matter interaction
Optical microcavities are an important tool for photonics technologies, providing enhancement and control over the light-matter interaction that is not available in macroscopic devices. Here I will present recent work in fabricating miniature Fabry Perot style cavities that compare in specifications to state-of-the-art photonic crystal structures, but bring a number of additional benefits including full in-situ tunability and efficient coupling to external optics. I will describe some of our first experiments with these cavities, in the fields of optical sensing and controlling the fluorescence properties of single quantum dots and colour centres in diamond.
Wednesday 25th February 2015 DB1.14 at 2.30pm
Professor Peter Barker, University College London - Levitated optomechanics
The ability to engineer and control the macroscopic motion of nano- and micro-mechanical oscillators has become an important tool in quantum science and technology. Key to the exploitation of these devices has been the development of methods to cool them to their ground state[1]. Levitation of a nanomechanical oscillator in vacuum, such as an optically trapped nanosphere, removes many dissipation and decoherence pathways and leads to extremely high mechanical quality factors[2]. This offers great promise for force sensing[3], for exploring the foundations of quantum mechanics at large mass scales and the possibility of creating large macroscopic superpositions[4]. In this talk I will introduce quantum cavity optomechanics and focus on the science and potential applications of levitated systems. Finally, I will describe our experiments that have cooled levitated 200 nm silica spheres in vacuum by using a hybrid electro-optical trap.
Wednesday 11th February 2015 DB1.14 at 2.30pm
Professor Adrian Kent, University of Cambridge, Cambridge Centre for Quantum Information and Foundations - Relativistic Quantum Cryptography: Controlling Information by Fundamental Physics
Quantum systems carry an intrinsically quantum form of information, which cannot be copied and allows much stronger control than classical information. Special relativity also allows the flow of information to be controlled through the no-superluminal-signalling principle. Together these have led to the emerging science and technology of relativistic quantum cryptography. I describe some applications, including verifying the location of a prisoner, using quantum teleportation to fake anything, running a secure quantum casino, and guaranteeing trust in the devices of untrustworthy cryptographic device builders. I also describe the first relativistic quantum cryptographic experiment, carried out recently by a Geneva-Singapore-Cambridge collaboration.
Wednesday 4th February 2015 DB1.14 at 2.30pm
Dr Chris White, University of Glasgow - Can protons tell us about quantum gravity?
Protons and neutrons are made of smaller particles called quarks and gluons, which are described by Quantum Chromodynamics (QCD). This is a quantum field theory, and underlies physics at particle accelerators like the Large Hadron Collider in CERN. Recently, an intriguing mathematical correspondence has been found between theories like QCD, and the theory of gravity (General Relativity). The hope is that we can use quarks and gluons to give hints of a long-sought after quantum theory of gravity, which is needed to explain extreme events in the universe, such as black holes and the Big Bang itself. This colloquium will review the correspondence between QCD and gravity, before describing recent research on this topic carried out in Glasgow and elsewhere.
Monday 28th January 2015 2015 DB1.14 at 2.30pm
Professor Barry Garraway, Physics and Astronomy, University of Sussex - Dressing up for quantum technology
We will review the development of atomic dressing for the control of cold atoms. Dressing with radio-frequency and microwave radiation opens new atom trap designs because of the flexibility inherent in the vector coupling of a magnetic dipole moment to EM fields which can be varied in time, frequency, orientation and space. This may in turn result in quantum technology applications to sensing, metrology and interferometry. This talk will introduce the concept of the dressed atom, and present both old and new designs of ring traps [1,2] and race tracks [3] with potential to make new atomic gyroscopes.
Previous Colloquia 2014
Thursday 11th December 2014 DB 3.15 at 2.30pm
Dr Bruno Sanguinetti, IdQuantique, Geneva - Quantum mechanics: from fun(damental) theory to practical applications
Wednesday 10th December 2014 DB 1.14 at 2.30pm
Professor Stefan Dilhaire, LOMA, CNRS - University of Bordeaux - Filming and Imaging Energy Transport at 10 Tera images per second
Energy transport is fundamental to both improving our understanding of basic material properties and advancing the intelligent design of new and more optimally functional materials. Energy transport is mediated by various particles and their subsequent interactions, including electrons, photons, phonons, plasmons, spinons, and excitons. The precise nature of any material determines which of these are most important. A more complete understanding of materials currently in development is of critical importance for a wide range of applications ranging from energy harvesting photovoltaics and thermoelectrics to next generation molecular electronics and mechanisms of material failure in nanoelectronics. Currently, there are a number of unanswered questions that are impeding the advancements of many important real-world applications, including the development of green technologies. Our research goal is to answer some of these questions. For example, how does nano-structuring --- such as changes in dimensionality, layering, and nanoparticle impregnation --- change energy transport characteristics? What effects do chemical and structural modifications on the near-field scale have on far field measurements of energy transport? Is it possible to decouple electronic and thermal transport in materials? What is the source of heat generation in nano electronics systems? The goal of this work deals with the design of materials with more precise and efficient control of energy transport by managing thermal properties of those systems or make them work to our advantage.
Currently, pump-probe spectroscopy is being successfully applied to energy transport measurements using techniques such as picosecond acoustics and time domain thermal reflectance with high temporal resolution [1]. These measurements, however, are limited by the diffraction to half the wavelength light. Quasiparticle excitations such as plasmon- [2] and phonon-polaritons [3,4] dominate near field, sub-wavelength effects, and high spatial resolution is required to probe them. Scanning-probe microscopy offers high spatial resolution and local probing of near field effects, but is wanting of temporal resolution. We will present different experimental approaches to detect, image and film phononic, electronic and plasmonic [5] energy transport.
Wednesday 3rd December 2014 DB1.14 at 2.30pm
Dr Steve James, Engineering Sciences Division, Cranfield University - Species specific chemical sensing using molecularly imprinted coatings on optical fibre long period gratings
The combination of photonic devices with functional nanomaterials offers great promise for the development of highly sensitive and selective chemical sensors. The team at Cranfield has been exploiting optical fibre long period gratings as a sensing platform, depositing thin (of order 100nm) coatings of chemically sensitive materials onto the fibre to provide selective response to target analytes. The presentation will provide an overview of the properties of long period gratings and discuss the means for optimising the sensitivity of the device to the optical properties of the surrounding material. The performance of sensors with a variety of coatings deposited via lay-by-layer techniques will be presented, with a focus on molecularly imprinted coatings, where template-shaped cavities are formed in polymers matrices and in metal oxide matrices are shown to offer selective sensitivity to target analytes.
Wednesday 26th November 2014 DB1.14 at 2.30pm
Professor Adrian Kent, Centre for Quantum Information and Foundations, University of Cambridge
Wednesday 19th November 2014 DB1.14 at 2.30pm
Dr Mohammed F Saleh, Institute of Photonics & Quantum Sciences, Heriot-Watt University - Nonlinear Photonics in Gas-filled Photonic Crystal fibres
Optical microstructures with truly unique properties have been developed at a fast pace in recent years as a result of the rapid progress in the fabrication techniques. Hollow-core photonic crystal fibres (HC-PCFs), microstructured waveguides with a two-dimensional periodic cross-section, offer unprecedented advantages that can lead to several fruitful opportunities for demonstrating and better-understanding new physical phenomena in optics. These fibres introduce the photonic bandgap effect in analogy to solid-state physics as an alternative guidance mechanism to the well-known total internal reflection. HC-PCFs have pushed the field of nonlinear fiber optics beyond the interaction of light with solid media. These structures can host strong nonlinear interactions between intense light and gaseous media over a relatively-long propagation distance. Having a wide range of gases with different properties enhances the opportunity to observe distinct novel nonlinear phenomena inside these structures. This can result in developing various novel photonic devices for diverse applications in the near future. In this talk, I will present novel nonlinear applications that are predicted and demonstrated in gas-filled HC-PCFs.
Wednesday 5th November 2014 DB 1.14 at 2.30pm
Mr Andreas Albrecht, Institute for Theoretical Physics, University of Ulm - Phonon coupling in nanocrystals and self-assembled nanodiamond devices
The embedding of the nitrogen-vacancy (NV) center in the diamond crystal lattice structure naturally involves the coupling to global vibrational (phonon) modes. However the coupling strength to these modes depends crucially on the dimensions of the diamond crystal [1]. I will show that for nanometer sized crystals, a well-separated acoustical mode spectrum paired with a significant and selective electron-phonon coupling can lead to discrete vibrational sidebands. Concepts are provided, that allow for harnessing the associated energy shift on the ground-excited state NV transition for coherent interactions within the ground state manifold. That way, conditional quantum gates can be constructed and further optimized by relying on a dispersive regime and by the combination with decoupling sequences .
In addition, a bottom-up approach for the creation of symmetric arrangements of NV centers will be presented [2]. This is based on attaching nanodiamonds to a self-assembled scaffold of proteins (SP1). Besides first experimental results, concepts for the practical implementation of quantum operations in such systems will be addressed. In particular, the creation of dynamically decoupled gate operations, the achievement of a uniform coupling and the ability for individual addressing.
[1] A. Albrecht, A. Retzker, F. Jelezko and M. B. Plenio, New J. Phys. 15 083014 (2013) [2]A. Albrecht, G. Koplovitz et al., arXiv:1301.1871, New J. Phys. 16 093002 (2014)
Wednesday 22nd October 2014 DB1.14 at 2.30pm
Dr Sam Chen, Institute of Photonics & Quantum Sciences, Heriot-Watt University - Metasurface for ultrathin planar optical devices
Miniaturization and integration are two continuing trends in the production of photonic devices. The functionality of a traditional photonic device is usually realized by reshaping the wavefront of the light that relies on gradual phase changes along the optical paths, which are accomplished by either controlling the surface topography or varying the spatial profile of the refractive index. The thickness of photonic devices usually remains comparable to the wavelength of the light. However, further reduction in the thickness of the corresponding element is hindered by the design theory since it is based on phase accumulation along the optical path. Metamaterials can usually be engineered to exhibit electromagnetic properties that may not be found in nature or its constituent components, thus providing an unconventional alternative to optical design. Metasurfaces, the emerging field of metamaterials, which consist of a single layer of artificial "atoms", have recently captured the attention of the scientific community since they do not require complicated three-dimensional nano-fabrication techniques but can control light propagation in equally dramatic ways. Unlike the phase change by the accumulated optical path in traditional optical elements, the abrupt phase change takes place at the metasurfaces, meaning that a new freedom for controlling light propagation is introduced. In this talk, I am going to talk about the recent development in the field of metasurfaces, and highlight our previous and current contribution to this research area.
Wednesday 1st October 2014 DB 1.14 at 2.30pm
Dr Sarah Croke, School of Physics and Astronomy, University of Glasgow - Quantum measurement and learning
Quantum information science has demonstrated conclusively that encoding and manipulating information in quantum states can offer distinct advantages over classical information processing. Learning about a quantum system however, is still widely considered to be a classical process – a measurement is made on the system, yielding some classical information, and disturbing the state in the process. Indeed what does it mean for a quantum device to learn about the state of an external quantum system? At its most fundamental, measurement is any process by which an observer or apparatus gains information through interaction with an external system. In this talk I will discuss measurement in quantum theory, from the textbook description of measurement of an observable, to generalised measurements used in quantum information theory, to finally a generalization of the notion of measurement in quantum theory, allowing the measuring device to itself be a quantum system, gaining quantum information. I will discuss the implications of such a generalization, with reference to applications to learning about an unknown multi-partite quantum state, and to quantum adaptive algorithms.
Friday 19th September 2014 DB1.13 at 11.00am
Professor Dirk Bouwmeester, Department of Physics, Center for Spintronics and Quantum Computation, University of California and Huygens Laboratory, Leiden University - Solid-state cavity QED
To interface photons with solid-state devices, we experimentally investigate the coupling of optically active quantum dots and rare earth ions to optical micro cavities. We demonstrate charge tunable quantum dots inside a polarization degenerate micropillar cavity and show how polarization resolved reflection and transmission spectroscopy can probe the coherence properties of the neutral and singly negatively charged quantum dot transitions [1-3]. We present a theoretical scheme for using this system for quantum logic operations [4].
Results on an alternative solid-state cavity QED system will also be presented. This system consists of a SiN ring resonator embedded in SiO2 [5] with implanted rare-earth ions. Rare earth ions are well known for their excellent coherence properties and currently there is a lot of excitement about the prospects of using such ions for quantum information processing purposes. We will demonstrate a system with a Purcell factor of 10 and argue that a Purcell factor of 100 is well within reach what makes communication with a single rare-earth ion in the solid state system possible [6].
Friday 8th August 2014 DB3.15 2.30pm
Dr Adolfo Esteban-Martin, Radiantis, formerly of ICFO, Barcelona - Novel Concepts in Femtosecond Optical Parametric Oscillators for Broadband, Dual-wavelength and Mid-IR Emission
Generation of coherent light in new regions of the optical spectrum has been a major goal of research in laser science and technology since Maiman demonstrated the first experimental laser in 1960.
Optical Parametric Oscillators (OPOs) offer a uniquely versatile solution that can overcome the spectral limitations of lasers and extend the accessible wavelengths to new limits with many applications in time-domain spectroscopy, optical microscopy, biophotonics and nanotechnology, among others.
In this talk, I will provide an introduction to OPOs and overview of some of the key elements to implement OPOs in femtosecond timescale. Moreover, I will address some of the novel concepts to achieve broadband, dual-wavelength and Mid-IR emission
Tuesday 26th August 2014 DB1.14 10.00am
Dr. Sarper Ozharar, Bahçeşehir University, Istanbul - Low Noise Optical Frequency Combs: Generation and Applications in Secure Optical Communications
In this talk, we will explain some general methods for generating and stabilizing optical frequency combs, and some of their applications in secure communication. One of the main applications we will discuss is the Alfa-Eta Quantum-Noise Aided Key Distribution method, which was successfully demonstrated at 155 Mb/s over 70 km of fiber.
Wednesday 30th July 2014 PGCG01 11.30am
Professor Tomas Tyc, Masaryk University, Czech Republic, SUPA Distinguished Visitor - Unusual phenomena of a usual day
Why don’t spinning tops fall over? Can water be carried in a sieve? If you are a scientist or science enthusiast you may know the answer to that, but did you know you can study properties of stress tensors on a piece of carrot?
Tomas Tyc is a world recognized expert in invisibility cloaking and perfect imaging. His lectures for specialized audience or general public are famous for their inspiring and entertaining nature complemented by a number of life demonstrations of ingenious simplicity. You’ll be surprised how much you can learn playing with humble and seemingly worthless things of your everyday experience. Everyone is welcome!
Wednesday 11th June 2014 DB 1.14 10.30am
SPIE Student Chapter, Guest Lecture 1
Dr. H. Philip Stahl, Senior Optical Physicist, NASA Marshall Space Flight Center - Rules for Optical Metrology
Optical testing is the discipline of quantifying the performance parameters of an optical component or system using any appropriate metrology tool. Based on 30 years of testing experience, he has defined seven guiding principles: Fully Understand the Task; Develop an Error Budget; Continuous Metrology Coverage; Know where you are; ‘Test like you fly’; Independent Cross-Checks; and Understand All Anomalies. These rules have been derived from his own failures and successes. And, these rules have been applied with great success to the in-process optical testing and final specification compliance testing of the James Webb Space Telescope (JWST) OTE mirrors.
Wednesday 11th June 2014 DB 1.14 2.30pm
Dr Marco Petrovic, University of Southampton - Development of Hollow Core Photonic Bandgap Fibres for Telecommunication Applications
Hollow Core Photonic Bandgap Fibres (HC-PBGFs) have been the subject of a resurging interest over the past few years. These fibres are emerging as serious contenders in the race to identify the best solution for next-generation high capacity transmission systems, owing to of their low nonlinearity, ultimate-low signal latency, near ideal match to thulium-doped fibre amplifiers and to the promise to deliver ultralow loss, potentially comparable or even below the level of state-of-the-art standard single mode fibres. Recently, substantial improvements in HC-PBGFs fabrication have been reported and data transmission experiments at both 1.55 µm and 2 µm wavelengths over multi-hundred meter lengths of HC-PBGF have been demonstrated. For these fibres to stand a realistic chance of competing with established and future all-solid transmission fibres, the key challenge is to attain the expected loss reduction over a wide transmission bandwidth. In this work we review recent progress in the development of HC-PBGFs including the realization of fibres with low loss and wide bandwidth through careful engineering of the fibre structure and control of their modal properties, which are paving the way to record-breaking data transmission experiments using mode division multiplexing. The talk will also look at other application areas with significant potential, which may benefit from recent improvements in the fabrication technologies and in the understanding of the properties of these complex fibre waveguides.
Wednesday 21st May 2014 DB 1.14 2.00pm
Dorothy Hardy, Heriot-Watt University - Boring squares get a colourful life: using fluorescent dyes to make crystalline silicon solar cells look good in glazing
I investigates ways of making solar cells look good as part of architecture. I use fluorescent dyes to change the colours of the solar cell encapsulates. This technology has minimal effect on the electricity output from the cells, unlike many other methods of altering the appearance of solar cells. I will present my recent work using traditional stained glass techniques.
Wednesday 21st May 2014 DB 1.14 2.30pm
Dr Chris Hooley, SUPA, University of St Andrews - How do you cool an atomic gas to nanokelvin temperatures (and what do you do with it then)?
Bose-Einstein condensation was first achieved in ultracold atomic gases almost twenty years ago. Since then, the manipulation and measurement of the resulting quantum-coherent fluids, and their fermionic analogues, has become a major field of scientific research. In this talk, I shall give an overview of the all-optical methods used to trap and cool such atomic gases. I shall then go on to describe some of the interesting phenomena so far observed, and also to say something about those (like Neel antiferromagnetism and perhaps even unconventional superconductivity) that remain elusive. The talk is non-technical, with an emphasis on the key concepts, and I assume as little prior knowledge of lasers or atomic physics as possible. All welcome!
Wednesday 21st May 2014 DB 1.14 3.30pm
Dr Raoul Frese, VU University Amsterdam - Biosolar cells: natural and artificial assemblies of light energy transducing protein complexes
The harvesting of solar energy in photosynthesis is dependent upon an interconnected macromolecular network of membrane associated chlorophyll-protein complexes. In the past decade my workgroup and others have elucidated the structure and functioning of these networks to great detail. Here I will briefly discuss our efforts in high resolution AFM imaging of native membranes and the models derived from light spectroscopy (1, 2). In the second part I will discuss our recent efforts in applying and mimicking the natural assemblies in hybrid biosolar cells, photosynthesis based electrodes as components for sensors (3), photovoltaics (4) and, possibly, photofuels. If time allows, I end with our recently designed algae powered robot which showcases the possibilities.
Wednesday 28th May 2014 DB 1.14 3.30pm
Dr Richard Blythe, University of Edinburgh - Macroscopic effects of athermal noise
In equilibrium systems, the nature of fluctuations around deterministic behaviour is restricted by the fluctuation-dissipation theorem. However, the vast majority of systems are not at equilibrium, but driven out of equilibrium by the environment or (in the case of living systems) though internal processes. As such, fluctuations may arise from a source other than a heat bath and are not constrained by the fluctuation-dissipation theorem. By examining the case of birth-death dynamics in populations - which exhibit highly athermal “demographic” fluctuations - we find that the same deterministic system subjected to noise of two different amplitudes can exhibit vastly different behaviour at the macroscopic scale. We reflect on the consequences of this finding for a variety of physical and not-so-physical systems.
Tuesday 8th April 2014 DB1.14 2.30pm
Dr Marcello Ferrera, Heriot-Watt University and Purdue University - Recent progress in nano-photonics: plasmonic materials and structures
Dr. Marcello Ferrera has recently been appointed Lecturer at the School of Engineering and Physical Sciences at Heriot-Watt University. He is currently involved in a three-year collaboration with the group of Prof. V. Shalaev at The Purdue University; a pioneer in the development of nano-photonics by exploiting plasmonic structures. In his talk, Dr. Ferrera will report about his most recent results dealing with: i) New materials in nano-photonics; ii) Emission enhancement of single photon source via interaction with hyperbolic metamaterials; and iii) Optically induced metasurfaces.
Wednesday 23rd April 2014 DB 1.14 2.30pm
Dr Adam Clare, University of Nottingham - Non-Conventional Parts via Non-Conventional Methods
The UK is a world leader in the design and manufacture of a range of high-value products which include aeroengines, bioimplants, micro-electronics and beyond. The economic destiny of the UK is closely linked to our capability in these areas alongside our propensity to innovate and stay ahead of the game.
Critical to maintaining commercial advantage in these industries will be maintaining and developing state-of-the-art manufacturing technologies which offer designers new freedoms. The complexity of next generation high-value components means manufacturing technologies must keep pace with requirements. These challenges are further complicated by the need to process materials which are evermore resistant to traditional manufacturing routes.
This talk will focus on research activity which is taking place at the University of Nottingham relating to the development of emerging manufacturing techniques (EBM, laser materials processing, EDCoating and additive manufacturing) for the stalwart, high-value industries of the UK.
Tuesday 29th April 2014 DB 1.14 2.30pm
Dr Keith Wilcox, University of Dundee - Fundamental properties of mode-locked semiconductor disk lasers and their development towards sources for large mode spaced frequency combs
For frequency combs the advantage of large mode spacing has become apparent due to the simplicity of isolating individual modes and the power per mode. Vibronic crystal lasers can reach this operating regime but are susceptible to Q-switching instabilities.
Mode-locked VECSELs have nanosecond upper state lifetimes and can produce sub-100-fs pulses at repetition rates between 1 and >100 GHz. They are also capable of continuous repetition rate tuning over ranges exceeding a factor of two.
Here I will discuss some of the challenges set by the semiconductor dynamics, and our approaches to tackle these, to develop VECSELs with multi-Watt average power and ~100 fs pulse durations for coherent supercontinuum generation.
Wednesday 30th April 2014 DB 1.14 2.30pm
Dr Michael Hartmann, Heriot-Watt University - Photons in Networks of Superconducting Circuits
Light consists of photons, mass-less particles that do not interact with one another in vacuum. Recent technological developments in superconducting circuits however enable us to engineer appreciable interactions between individual microwave photons in multiple nodes of a network simultaneously. In this talk, I will present some of our recent investigations for such devices. On the one hand, strong photon-photon interactions can be employed to logically process information that is carried by the photons. Here I will discuss a scheme for a single photon transistor. On the other hand, such interactions allow us to drive photons into novel strongly correlated quantum many-body regimes. Interestingly, these may by studied in non-equilibrium scenarios where inevitable photon losses are constantly compensated by input drives. They thus give rise to an intriguing class of quantum many-body systems where instead of ground or thermal states one is interested in the still largely unexplored stationary states of their driven and dissipative dynamics. Here I will present some of our recent results for the phase diagrams for their stationary states.
Wednesday 12th March 2014 DB 1.14 2.30pm
Professor Raffaella Ocone, Heriot-Watt University - Making the link between micro and macro: from particle-particle interactions to carbon capture technologies
The talk presents an overview of current research topics in chemical engineering including the physics of granular flow and the separation of flue gases. The areas where multidisciplinary research is needed are highlighted and the technological challenges discussed.
Wednesday 5th February 2014 DB 1.14 2.30pm
Dr Matteo Clerici, INRS, Montreal, Canada - Filling the Terahertz Gap
The range of the electromagnetic spectrum between 0.1 and 10 THz is often referred to as the terahertz gap, owing to a substantial lack of sources and detectors. Standard electronic approaches do not work effectively at such high frequencies, while optical ones also fail at such long wavelengths. This region of the spectrum is therefore open to fundamental research as well as technical challenges. We shall present our recent journey into the terahertz spectral region and our results in the quest of closing the THz gap. The main idea that motivates our research is that long wavelengths are best suited for driving the motion of the electrons. This general concept will play a major role both in terms of applications of terahertz photonics and for enhancing the terahertz generation itself. Topics like THz generation from plasma, THz imaging, broadband THz detection, THz enhanced spectroscopy and thermometry will be tackled.
Wednesday 12th February 2014 DB 1.14 2.30pm
Dr Tomas Cizmar, University of Dundee - Photonics in disordered environments and fibre based imaging
Astronomical observations from ground-based telescopes are degraded by the random and rapidly varying distribution of refractive index in the Earth’s atmosphere. Similarly, in Biology and Medicine, imaging of tissues and living organisms at visible wavelengths is limited by the highly scattering and absorbing nature of these environments; image quality and maximum image depth are both reduced by these conditions.
Optogenetics is one of the rapidly evolving modern disciplines that would particularly benefit from the possibility to provide the optimal performance of imaging devices and bio-photonics techniques in vivo.
Novel holography-based strategies to correct these unwanted deviations from the ideal wavefront and thereby redeem the optimal performance of bio-photonic systems in such turbid media will be discussed in the lecture. In addition to their high Bio-Medical relevance, these methods represent a powerful approach towards full understanding of laser light propagation through any randomizing system.
An important example of this is light transmission within a multimode optical fibre. Coherent light propagating through such waveguide is randomized but the image information is not lost and can be decoded once the overall response of the system is measured. The possibility of converting the random output signal into a diffraction limited focus, as well as any other light shapes, will be discussed together with a number of applications including optical manipulation and imaging.
1. In situ wavefront correction and its application to micromanipulation. Čižmár, T., Mazilu, M. & Dholakia, K. Nature Photonics 4 388-394 (2010).
2.Shaping the light transmission through a multimode optical fibre: complex transformation analysis and applications in biophotonics. Čižmár, T. & Dholakia, K. Optics Express 19(20) 18871-18884 (2011).
3. Shaping the future of manipulation. Dholakia, K. & Čižmár, T. Nature Photonics. 5 335-342 (2011)
4. Exploiting multimode waveguides for pure fibre based imaging. Čižmár, T. & Dholakia, K. Nature Communications (2012).
Wednesday 19th February 2014 DB 1.14 2.30pm
Dr Andrea Aiello, Max Planck Institute for the Science of Light, Erlangen, Germany
Angular momentum of light
Every student knows that massive spinning objects, like a bicycle wheel, possess an angular momentum directed along the axis of rotation. Perhaps fewer students know that also non-massive physical systems, as light, may exhibit an angular momentum which becomes manifest when light interacts with matter. In this talk I will present a general survey of the concept of angular momentum of light mainly focusing on its historical development. In addition, I will illustrate some examples of relevant practical and fundamental applications of this fascinating and timely subject. In particular, the so-called geometric spin Hall effect of light will be illustrated in some detail.
Wednesday 26th February 2014 DB 1.14 2.30pm
Dr Jonathan Leach, Heriot-Watt University - From ghost imaging to quantum tomography: an introduction to inverse problems
Wednesday 22nd January 2014 DB 1.14 2.30pm
Professor Matteo Conforti, University of Brescia, Italy - Extreme waves in nonlinear optics
I will discuss the development of wave with extreme features in the domain of nonlinear optics. These extreme waves are encountered in several physical settings, ranging from oceanography to optics, form physics of the atmosphere to Bose-Einstein condensation. The focus is mainly on two processes, namely Rogue Waves (RW), that is the generation of waves of unexpectedly high amplitude from a calm state, and Dispersive Shock Waves (DSW), that is the evolution of steep fronts towards a discontinuity (wave breaking), followed by a regularization through fast oscillations.
I will show the development of extreme waves in different nonlinear optical media, characterized by quadratic or cubic nonlinear response, and the effects on spectral broadening through the emission of novel kinds of resonant radiation.
Wednesday 29th January 2014 DB 1.14 2.30pm
Dr Dave Towsend, Heriot-Watt University - Making Molecular Movies: Chemical Physics in Action
In order to understand the intricate details of chemical change, the fundamental physics behind such processes must be studied in detail. This talk, primarily aimed at undergraduates, will introduce methods for achieving this goal that make use of “ultrafast” femtosecond lasers to enable the real-time dynamics of energy flow in molecules to be observed – i.e. making molecular movies. These experiments, which draw on many different aspects of physics (lasers & optics, vacuum science, charged particle imaging, quantum mechanics & spectroscopy, etc.), provide a great deal of insight into key pathways that drive the evolution of chemical reactants to chemical products. Specific examples will then focus on processes found in nature that protect living organisms from the potentially damaging effects of ultraviolet light via so-called “photo-protection” mechanisms.
Previous Colloquia 2013
Wednesday 9th January - DB 114 - 2.30pm:
Prof Deepak Mathur, Tata Institute of Fundamental Research, Mumbai India Ultrafast science: Adventures on the interface of physics, chemistry and biology
Access to ultrashort laser pulses that last long enough to accommodate only a few optical cycles, is beginning to allow time-dependent nuclear and electron dynamics to be probed within atoms and molecules, thereby enhancing our ability to gain proper insights into how quantum systems react to strong external fields and how they might be subjected to optical control. In this talk I shall present an overview of how we have utilized intense laser pulses of duration as short as ~4 fs to explore dynamical effects of relevance to diverse areas of the physical and engineering sciences, including applications pertaining to DNA damage, laser-induced materials modification and green photonics
Wednesday 16th January - DB 114 - 2.30pm:
Prof Ian Galbraith, Heriot Watt University Optical Physics in Organic Semiconductor Molecules
Organic semiconductor materials offer the potential of low-cost and flexible displays and lighting solutions, some of which have already made it to the market place. Despite this much of the underlying optical physics remains poorly understood and hinders progress towards better and more powerful devices. In this talk the basic properties of organic semiconductors will be reviewed and some of the outstanding issues explored. We will show how simple models based on dipole-dipole coupling can be validated (by comparison with quantum chemistry) and used to compute optical properties such as absorption, gain and luminescence spectra. Recent theoretical and experimental results on the optical pulse propagation and timescales of excitation transfer and hopping in linear oligoflourine and star-shaped samples will be also presented.
Wednesday 23rd January - DB 114 - 2.30pm:
Dr Sonja Franke-Arnold, University of Glasgow Orbital angular momentum in light, atoms and ruby
Wednesday 6th February - DB 114 - 2.30pm:
Professor Chiara Macchiavello, University of Pavia Detecting entanglement
A brief review of the concept of entanglement for bipartite and multipartite quantum systems, and an introduction to the general framework of entanglement detection, will be initially given. Then a recently proposed method to detect entanglement in multipartite systems based on the notion of structure factors will be presented. The concept of structure factors will be briefly introduced and, in particular, a relation between entanglement of a many-body system and its diffractive properties, where the link is given by structure factors, will be shown. Such a method allows to detect multiqubit entanglement via two-point correlations and can be implmented either in a scattering experiment or via local measurements, depending on the underlying physical system. Some explicit examples of states that can be detected in this way and a discussion of possible applications will be finally given.
Wednesday 20th February - DB 114 - 2.30pm:
Dr Bernhard Urbaszek, CNRS-Toulouse University, LPCNO Optical Manipulation of the Spin and Valley degree of freedom in semiconductor nano-structures
The mesoscopic spin system formed by the 10E4–10E6 nuclear spins in a semiconductor quantum dot offers a unique setting for the study of many-body spin physics in the condensed matter. The dynamics of this system and its coupling to electron spins is fundamentally different from its bulk counterpart or the case of individual atoms due to increased fluctuations that result from reduced dimensions. In recent years, the interest in studying quantum-dot nuclear spin systems and their coupling to confined electron spins has been further fueled by its importance for possible quantum information processing applications. The fascinating nonlinear (quantum) dynamics of the coupled electron-nuclear spin system is universal in quantum dot optics [1] and transport. In the first part of this talk, experimental work performed over the last decade in studying this mesoscopic, coupled electronuclear spin system is reviewed, with special focus on how optical addressing of electron spins can be exploited to manipulate and read out the quantum-dot nuclei. The second part of the talk will be devoted to another degree of freedom: the valley index of electrons in atomically thin two-dimensional crystals. Monolayer MoS2 has emerged as a very promising material for optoelectronic and spin applications for mainly two reasons: First, the indirect bulk semiconductor MoS2 becomes direct when thinned to one monolayer, resulting in efficient optical absorption and emission. Second, the inherent inversion symmetry breaking (usually absent in graphene) together with the strong spin-orbit interaction leads to a coupling of carrier spin and k-space valley physics [2]. The resulting chiral optical selectivity allows exciting one of these non-equivalent K valleys. Both the magnetic field and the temperature dependence of this optical initialization of the valley index will be discussed [3] in the context of preparing valley-Hall coupled to spin-Hall measurements.
[1] B. Urbaszek et al, Reviews of Modern Physics 85, 79 (2013) [2] D. Xiao et al, Phys. Rev. Lett. 108, 196802 (2012) [3] G. Sallen et al, Phys. Rev. B 86, 081301(R) (2012)
Wednesday 27th February - DB 114 - 2.30pm:
Dr Jennifer Hastie, University of Strathclyde Semiconductor disk lasers for high brightness with broad tuning
Semiconductor disk lasers (SDLs), also known as vertical external-cavity surface-emitting lasers (VECSELs) are optically-pumped semiconductor lasers, with oscillation perpendicular to the epitaxial gain structure. Importantly they have an external laser resonator, typically millimetres up to tens of centimetres in length, and therefore differ significantly from the more common VCSEL format in terms of laser operating characteristics. SDLs are in many ways more akin to conventional doped dielectric solid-state lasers; however, they have outstanding wavelength flexibility combined with their excellent beam quality, where their wavelength versatility stems from semiconductor bandgap and quantum well engineering in the gain structure and the fact that their fundamental spectral coverage can be further extended by efficient, intra-cavity nonlinear frequency conversion. This talk will give an overview of SDLs with particular emphasis on the spectral coverage achieved – design, principles of operation, materials, and typical performance – and will review the various techniques used and results obtained for continuous wave operation, intra-cavity frequency filtering, and nonlinear frequency conversion, including recent work at the IoP on intra-cavity-pumped diamond Raman lasers.
Wednesday 6th March - DB 114 - 3.45pm:
Dr Janet Lovett, University of Edinburgh Nanometre length distances measured by EPR spectroscopy
Electron paramagnetic resonance (EPR) spectroscopy has always been a useful tool for investigating the structure of materials, including biological systems such as proteins. However, over the last 15 years techniques have emerged for the precise measurement of nanometre-scale distances and this sparked a renaissance in the development and application of EPR. This is because these nanometre distances can be measured for materials which cannot be accurately studied by other techniques (for example NMR or X-ray crystallography for proteins). This presentation will introduce the principles behind the technique and present examples of applications for the study of nanowires and protein-protein complexes.
Wednesday 13th March 2013 DB 1.14, 2:30 pm
Dr Giovanna Morigi, University of Saarland Entanglement in crystalline structures
A string of trapped ions at zero temperature exhibits a structural phase transition to a zigzag structure, tuned by reducing the transverse trap potential or the interparticle distance. The transition is driven by transverse, short wavelength vibrational modes. We argue that this is a quantum phase transition, which can be experimentally realized and probed. Indeed, by means of a mapping to the Ising model in a transverse field, we estimate the quantum critical point in terms of the system parameters, and find a finite, measurable deviation from the critical point predicted by the classical theory. A measurement procedure is suggested which can probe the effects of quantum fluctuations at criticality.
We then analyse the case, when an optical transition of the ions strongly couples to the mode of a high-finesse resonator. Here, the mechanical force of light concurs in determining the crystal properties. Such force depends on the position of all ions coupling to the field, and is a manifestation of a photon-mediated interaction. While this interaction is usually small compared to the Coulomb repulsion, it can become significant close to a structural instability. In this situation the instability can be driven by the intensity of the laser pumping the resonator. At large cooperativity, in particular, parameter regimes are found for which both linear and zigzag arrays are stable in finite chains, in contrast to free space where the structural transition is continuous. For these regimes photonic and vibrational excitations are strongly coupled. This effect is visible in the spectrum of light at the cavity output. When the crystal vibrations are cooled by the cavity field, Fano-like resonances are observed. These feature correspond to entanglement between vibrational and cavity field fluctuations, which characterize the stationary state of the crystal.
We finally discuss a procedure for creating coherent superpositions of motional states of ion strings. The motional states are across the structural transition linear-zigzag, and their coherent superposition is achieved by means of spin-dependent forces, such that a coherent superposition of the electronic states of one ion evolves into an entangled state between the chain's internal and external degrees of freedom. It is shown that the creation of such an entangled state can be revealed by performing Ramsey interferometry with one ion of the chain.
Friday 22nd March 2013 DB 1.13, 2:15 pm
Dr Roger Haynes, Leibniz-Institut für Astrophysik Potsdam (AIP) Astrophotonics – Applications of Photonics in Astronomy
Astrophotonics (the application of photonic principles in astronomy) is rapidly developing field that has emerged over the past decade in response to developments in photonics and the increasing demands of astronomical instrumentation for the current and next generation optical/Infrared telescope facilities. Applications include: (i) frequency combs for ultra-high precision spectroscopy based on non-linear fibres or micro-resonators to, for example, detect planets around nearby stars, (ii) ultra- broadband fibre Bragg gratings or micro-resonators to suppress unwanted background from the night sky; (iii) mode transformations that provide both multimode to multimode transition in fibre tapers, and multimode to single mode transitions in photonic lanterns that facilitate “clean” implementation of photonic function; (iv) planar waveguides devices, based on Arrayed Waveguide Gratings (AWGs), for miniaturize astronomical spectrographs. The Astrophotonics research that will be presented is aimed at developing photonic devices for astronomy within the optical and near- IR wavelength regime (~320-2500nm).
Wednesday 10th April 2013 DB 1.14 11.15am
Professor David Miller, Stanford University - Optical interconnects: opportunities and device challenges
It is now well understood that optics is the main, and possibly the only, physical solution that could allow interconnects to continue to scale down in energy per bit and up in density of information, especially for interconnects off chips and at longer distances. The continuing growth of usage in the internet and in the data centers that feed the information demands continuing scaling of interconnects at all levels, with density and energy being key drivers. This talk will summarize these trends and discuss the kinds of technologies that may be needed, including optical and optoelectronic devices and their integration with silicon electronics. Recent examples including novel nanophotonic structures for wavelength splitting, new tunable and efficient resonant photodetectors in silicon, and sub-fJ/bit record low energy modulators will be discussed.
Wednesday 24th April 2013 DB 1.14 2.30pm
Professor Amin Abdolvand, University of Dundee - Fabrication and nanoengineering of metal-glass nanocomposites
The red and yellow colours of many medieval church windows originated from silver, gold and copper nanoparticles embedded in the window glass. The first evidence of using gold nanoparticles in antiquity dates back to the 4th century AD (the Lycurgus Cup). The physics of the processes remained a mystery until Michael Faraday, the well-known 19th century physicist, discovered that this effect is due to a new type of optical absorption in metal particles with dimensions substantially less than the wavelength of light. When a metal particle is smaller than the wavelength of light, the light reflected from it is replaced by light scattering, which is particularly strong at the resonance frequencies of collective electron excitations in the particle. These oscillations are known as the particle’s plasmons or surface plasmon resonances (SPRs). Glasses containing embedded metallic nanoparticles (metal-glass nanocomposites) exhibit peculiar linear and non-linear optical properties, mainly due to the SPRs of the metallic inclusions. The nanoparticles’ shapes and spatial distribution, predominantly and characteristically, determine polarisation dependence and spectral positions of the SPRs in the visible and near infrared. The main focus of this talk is on the interaction of (short and ultra-short) laser pulses as well as DC electric field with silver nanoparticles embedded in soda-lime glass, the resulting structural modifications and their emerging applications.
Thursday 25th April 2013 DB 1.14 2.15pm
Professor David Miller, Stanford University - How to design any linear optical component and how to avoid it
Though we can readily understand any particular linear optical device, we have not in general known how to design one to do just what we want. At worst, we have to resort to blind, trial-and-error iterative processes, with no guarantee that the device is even possible. For example, current challenging practical devices include efficient arbitrary spatial mode splitters and converters for communications through free-space or in multimode fibres, especially avoiding any fundamental power splitting loss. Here we show a new constructive, progressive, non-iterative method to design any arbitrary linear optical device or, indeed, any linear operation on waves, including microwaves, acoustics and quantum mechanical superpositions. We propose practical approaches for spatial optical devices that could be implemented, for example, in silicon photonics. The existence of this design approach also proves, in the spirit of a universal machine, that any linear wave device is possible in principle. Surprisingly, we show that all these designs can be completed without performing any calculations at all.
Tuesday 18th June 2013 DB 1.14 2.30pm
Professor Evelyn Hu, Harvard University- Quantum Dot-Microdisk Cavities in the InGaN/GaN Material System
Quantum dots (QDs) coupled to high quality nanocavities have served as outstanding platforms for understanding cavity quantum electrodynamics (cQED) in solid state systems. Such coupled QDs embedded within microdisks or photonic crystal cavities in the GaAs material system have demonstrated single photons on demand, enhanced radiative emission and strong coupling. Similar achievements in other material systems have proven to be more challenging, both in the quality of the materials and thus in the quality factors achievable for cavities formed from those materials. Our studies in the nitride materials comprise a variety of QD densities, microdisk thicknesses and direct comparisons with quantum well structures. By tracking the related cavity quality factors and the lasing thresholds of these QD-microdisk systems, we can come to a better understanding of the important factors in material quality and structural design that lead to the lowest lasing thresholds, and ultimately to the best coupling between QDs and cavity..
Friday 19th July 2013 EM 2.33 2.30pm
Dr Parama Pal, Bosch Centre - Innovation for impact @ RBCCPS
The Robert Bosch Centre for Cyber Physical Systems (RBCCPS) is an interdisciplinary centre at the Indian Institute of Science (IISc) with a focus on promoting applied research in cyber physical systems across verticals as diverse as healthcare, green infrastructure, and smart transportation enabled by a 2 million euros per year grant over a period of 10 years from the Robert Bosch Foundation. The centre strives to create an ecosystem for innovation by identifying impactful problems and technologies and recasting them so that they are addressable by researchers, technologists, societal, and commercial entities both within as well as outside IISc. In this talk, I will briefly describe some of the projects that are underway at the Centre and highlight the mechanisms by which we engage with present as well as with future collaborators.
Wednesday 21st August DB 1.14 2.15pm:
Dr John Morton, University College London - Atomic clock transitions in silicon-based spin qubits
Wednesday 21st August DB 1.14 2.45pm:
Professor Stephen Lyon, University of Princeton - Implementing surface codes using bismuth doped silicon
Wednesday 23rd October DB 1.14 3.30pm (Please note later time)
Professor Klaus Mølmer, Aarhus University - Quantum jumps: a bumpy road to light-matter interaction
This year marks the Centennial of Niels Bohr’s model of atoms and molecules by which he explained the observed discrete absorption and emission spectra of light.
The radiation energy is absorbed and emitted in quanta, proposed by Planck and Einstein in 1900 and 1905, and Bohr associated with each absorption and emission event a quantum jump: an electron jumps among a discrete set of allowed orbits of motion in the atom. Energy is conserved if the difference between motional energies in the different orbits equals the energy of the light quantum, ΔE=hf.
In 1926, the eigenfunctions and the discrete spectrum of the stationary Schrödinger equation replaced Bohr’s description in terms of electron orbits. Both the light quantum and the quantum jump hypotheses then became largely superfluous and, to a large extent, even in disagreement with the quantum mechanical description of optical processes in atoms and molecules.
In this talk, I shall review how the light quanta at first lost, but later regained their role as important ingredients in light-matter quantum interactions, and how the quantum jumps first disappeared completely from the formal quantum theory, but are now essential in the description and application of quantum phenomena.
Wednesday 6th November DB 1.14 2.30pm
Professor Thorsten Ackemann, University of Strathclyde - Optomechanical nonlinearities and self-organization in cold atomic gases
Monday 11th November DB 1.14 5.15pm
Professor Albert Stolow, National Research Council Canada Departments of Physics & Systems Biology, University of Ottawa, Canada Departments of Physics & Chemistry, Queen's University, Canada - Ultrafast Molecular Sciences
Ultrafast laser science has led to significant progress in molecular dynamics studies, particularly for the difficult but general case of non-Born-Oppenheimer dynamics. Quantum control methods further enhance molecular dynamics studies by permitting direct Molecular Frame measurements. As laser fields get stronger, a sub-cycle (attosecond) physics emerges, leading to new probes of driven multi-electron dynamics in polyatomic molecules. In condensed phases, ultrafast lasers permit simplified approaches to label-free nonlinear microscopy of live cells and tissues.
Wednesday 13th November DB 1.14 2.30pm
Professor Myungshik Kim, Imperial College - Quantum optomechanics
Quantum theory was known to describe the physics of very small systems. As an effort to test quantum mechanics in a macroscopic system there have been growing interests in studying nano-scale mechanical oscillators. In this colloquium, we discuss theoretical proposals on how to prepare and probe quantum states of mechanical oscillators using their interaction with optical fields.
Wednesday 20th November DB 1.14 2.30pm
Professor Stefan Kuhr, University of Strathclyde - Probing strongly correlated quantum systems with single-atom resolution
Ultracold atoms in optical lattices are a versatile tool to investigate fundamental properties of quantum many body systems. In a series of experiments I demonstrated how the control of such systems can be extended down to the most fundamental level of single atomic spins at specific lattice sites. Using a high-resolution optical imaging system, we were able to obtain fluorescence images of strongly interacting bosonic Mott insulators with single-atom and single-site resolution and addressed the atomic spins with sub-diffraction-limited resolution. In addition, we directly monitored the tunneling quantum dynamics of single atoms in the lattice, and observed quantum-correlated particle-hole pairs spreading of correlations after a parameter quench, and the quantum dynamics of spin-impurities. A new experimental setup involving fermionic 40K is currently under construction at the University of Strathclyde. Our goals are the single-atom-resolved observation of strongly correlated fermionic systems, implementation of novel cooling schemes, engineering of quantum many-body phases and experiments for quantum information processing.
Wednesday 27th November DB 1.14 2.30pm
Professor Christiane de Morais Smith, University of Utrecht - Title & abstract to follow
In the first part of this talk, I will consider ultracold bosons in optical lattices, which are excited to higher bands. The interplay between a contact interaction and the orbital degeneracy in the second band of an optical square lattice potential leads to a complex valued Px + i Py superfluid order, characterized by a spontaneously generated pattern of staggered currents. Our calculations in the framework of a multi-band bosonic Hubbard model exhibit good agreement with the experimental findings [1]. In the second part of the talk, I will discuss a recently proposed setup, for engineering artificial graphene-like structures. This system consists of a honeycomb superlattice of self-assembled semiconducting nano-crystals. A very interesting band structure emerges, with Dirac cones in the s- and p-bands [2]. By manipulating the chemical composition of the nanocrystals, it is possible to engineer a graphene lattice with strong spin-orbit coupling, which could lead to the observation of the quantum spin-Hall effect at room temperature [3]. For details of the quantum spin Hall effect in graphene-like lattices, see e.g. [4,5].
[1] M. Olschlager, T. Kock, G. Wirth, A. Ewerbeck, C. Morais Smith, and A. Hemmerich, New Journal of Physics, 15, 083041 (2013). Featured in the Journal Club for Condensed Matter Physics, Sept. 2013 [2] E. Kalesaki, C. Delerue, C. Morais Smith, G. Allan, and D. Vanmaekelbergh, submitted to PRX (2013). [3] W. Beugeling, E. Kalesaki, C. Delerue, Y.-M. Niquet, D. Vanmaekelbergh, and C. Morais Smith, in preparation. [4] W. Beugeling, N. Goldman, and C. Morais Smith, Phys. Rev. B 86, 075118 (2012). [5] N. Goldman, W. Beugeling, and C. Morais Smith, EPL 97, 23003 (2012), EPL highlight 2012.
Wednesday 11th December DB 1.14 2.30pm
Professor Mark Dennis, University of Bristol - Reflections on reflecting light: Classical weak measurement and singularimetry
When light beams of finite width are reflected by a mirror or dielectric surface, the reflected beam is displaced from the incident beam, and its direction is not quite equal to the angle of incidence. These effects, known as 'optical beam shifts' (including the Goos-Hänchen effect, Imbert-Fedorov effect, optical spin-Hall effect, ...) can be understood by an analogy between the finite-width light beam, and a time-evolving quantum wavepacket, for which beam shifts are precisely a classical waves analogy with quantum weak measurements introduced by Aharonov and others in the 1980s. This analogy gives insight into the meaning and interpretation of measurements in quantum mechanics.
When the light beams are structured before reflection, such as including optical singularities (vortices) on-axis (as Laguerre-Gaussian modes), the shape of the reflected light beam is also distorted, in a way that can be exactly understood using simple properties of complex functions. For incident optical vortex beams, the resulting constellation of vortices provides deep singularimetric information about the physics of reflection, which can be generalized to arbitrary weak optical scattering.
Previous Colloquia 2012
Wednesday 1 February – DB114 – 2:30pm Professor Gerard De Groot, School of History, St Andrews University, Physics & Society: Atoms for War and Peace Wednesday 15 February – DB114 – 2:30pm Dr Brendon Lovett, EPS, Heriot-Watt University, New Perspectives on the Feasibility of Spin-Based Quantum Computing Wednesday 29 February – DB114 – 2:30pm Professor Steve Barnett, Strathclyde University, The Enigma of Optical Momentum Wednesday 7 March – Postgraduate Centre Auditorium – 3:30pm Professor Rolf Heuer, CERN Director General, Geneva, The Search of a Deeper Understanding of our Universe at the Large Hadron Collider: the World’s Largest Particle Accelerator Wednesday 14 March– DB114 – 2:30pm Dr James Thompson, Department of Psychology, University College London, Intelligence and Science Wednesday 28 March– DB114 – 2:30pm Professor Ulf Leonhardt, University of St Andrews, Geometry, Light and a Wee Bit of Magic Tuesday 3 April – Postgraduate Centre Auditorium – 2:30pm Life Sciences Interface Professor Thomas Steitz, Nobel Laureate, Department of Molecular Biophysics and Biochemistry, University of Yale, USA, From the Structure and Function of the Ribosome to New Antibiotics Friday 20 April – DB114 – 2:30pm Celebration of the 2011 Nobel Prize in Chemistry Professor Danny Schechtman, Nobel Laureate, Department of Material Sciences, Technion, Israel, Quasi-periodic Materials—Crystal Re-defined Wednesday 25 April – DB114 – 2:30pm Dr Richard Szabo, MACS, Heriot-Watt University, Signatures of Noncommutative Spacetime
Wednesday 29 August – DB114 – 2:30pm Dr Matteo Conforti, Università di Brescia, Description Modelling of supercontinuum generation in quadratic crystals Wednesday 12 September – DB114 – 2:30pm Dr Kartik Srinivasan, NIST, Manipulating the Color and Shape of Single Photons generated by Quantum Nanophotonic Devices Wednesday 26 September – DB114 – 2:30pm Prof Yuansheng Wang,Fujian Institute of Research on the Structure of Matter (Chinese Academy of Sciences), title: TBA Wednesday 17 October – DB114 – 2:30pm Prof Per Delsing, Chalmers University, Quantum optics with microwave photons in superconducting circuits; dynamical Casimir effect and artificial atoms Wednesday 31 October – DB114 – 2:30pm Dr Jonathan Leach, Heriot Watt University, Description Quantum state characterisation through tomography and direct measurement Wednesday 14 November – DB114 – 2:30pm Prof Anthony Kent, University of Nottingham Semiconductor acoustic lasers (sasers) – a big noise from nanostructures Wednesday 28 November – DB114 – 2:30pm Prof Pablo Loza-Alvarez, ICFO Barcelona, title TBA Wednesday 12 December– DB114 – 2:30pm Dr Fabio Biancalana, Heriot Watt University, Description Photonic Crystal fibres: new devices and applications for extreme nonlinear optics
Previous Colloquia: 2011
Wednesday 26 January – DB114 – 2:30pm Dr Elham Kashefi – University of Edinburgh, Can we trust a Quantum Computer? Wednesday 16 February – DB114 – 2:30pm Professor Sir Peter Knight, FRS – Imperial College and Principal of Kavli Royal International Centre, Imaging Quantum States Wednesday 2 March – DB114 – 2:30pm Dr Linda Hadfield – University of Edinburgh, Science Education Research and Reform Wednesday 9 March – DB114 – 2:30pm Dr Sabrina Maniscalco – Heriot-Watt University, Long life to Quantum Correlations! Wednesday 23 March – PGC Auditorium – 2:30pm Professor Sir Roger Penrose, FRS – University of Oxford, Can we see through the Big Bang into another world? Wednesday 13 April – DB114 – 2:30pm Professor Serge Reynaud – University of Paris, Quantum Vacuum and the Casimir Effect Thursday 5 May - PGC Auditorium – 2:30 pm Professor Claude Cohen-Tannoudji, Nobel Laureate – Ecole Normale Superieur, Paris, Using light for manipulating atoms Wednesday 1 June – DB114 – 2:30pm Professor Renate Loll – University of Utrecht, The Netherlands, Searching for the Quantum Origins of Space and Time Wednesday 12 October – DB114 – 2:30pm Life Sciences Interface Professor Nick Hastie, FRS – Director of the Institute of Genetics, Edinburgh University, Cancer, Development and Adult Tissue Maintenance Wednesday 19 October– DB114 – 2:30pm Professor Anna Sanpera, Universitat Autonoma de Barcelona, Spain, Watch Out: Cold Atoms at Work Wednesday 26 October – DB114 – 2:30pm Dr Daniele Faccio, EPS, Heriot-Watt University, Optics in Non-Stationary Media: from Hawking Radiation to the Dynamical Casimir Effect Wednesday 2 November– DB114 – 2:30pm : Science & Art Films by Mr Peter McLeish, Film Director (USA), The Hundred-Year Hunt For The Red Sprite (42 minutes) & Lightning`s Angels (6 minutes) Wednesday 16 November – Postgraduate Centre Auditorium – 2:30pm Professor Serge Haroche, Laboratoire Kastler-Brossel, Paris, Juggling with atoms and photons in a cavity Wednesday 23 November – Postgraduate Centre Auditorium – 2:30pm Professor Anton Zeilinger, University of Vienna, Quantum Games, Quantum Information, and the Foundations of Quantum Physics Wednesday 30 November – DB114 – 2:30pm Physics & Society Professor Gerard De Groot, School of History, St Andrews University, Atoms for War and Peace
Previous Colloquia: 2009-2010
Wed 29 September - PG Centre Auditorium – 5:30pm Professor Klaus von Klitzing, Nobel Laureate – Max Planck Institute, Stuttgart, Germany: Thirty Years of the Quantum Hall Effect Wed 20 October – DB114 – 2:30pm Professor Ben Murdin – University of Surrey: Applications of atomic physics in solid state electronics Wed 3 November - DB114 – 2:30pm Dr Antony Valentini – Imperial College: Beyond the Quantum Wed 17 November - PG Centre Auditorium – 3:30pm Professor Gerard ‘t Hooft, Nobel Laureate – University of Utrecht, The Netherlands: Black Holes in Elementary Particles Wed 8 December - PG Centre Auditorium – 2:00pm Professor Albert Fert, Nobel Laureate – Thales Group, France: The world of spintronics: electrons, spins, computers and telephones
31 March Professor Sir David Wallace, FRS – Director Isaac Newton Institute, Cambridge: Five Millennia of Mathematics and its Applications Hosts: Karen Schmid (Petroleum) & Eitan Abraham Thu 18 March Professor Sir Richard Friend, FRS – University of Cambridge: Charge Separation from Excitons in Organic Semiconductors 3 March Dr Stephen Sweeney – University of Surrey: The Best of Both Worlds – Physics with a Commercial Spin 24 February Professor Ray Bishop – University of Manchester: Magnetic Order and Dimerisation in Low-Dimensional Antiferromagnets 10 February Professor Sir Michael Berry, FRS – University of Bristol: Conical diffraction: imaging Hamilton's diabolical point 3 February Dr Pavel Ostrovsky – University of Karlsruhe: Interaction-induced Criticality in Topological Insulators Host: Misha Titov
27 January Professor Jeremy O’Brien – Bristol University: Photonic quantum logic in waveguide circuits Host: Robert Hadfield