Optical cooling using the dipole force

The term 'laser cooling' is applied to the use of optical means to cool the motional energies of either atoms and molecules, or micromirrors. In the literature, these two strands are kept largely separate; both, however suffer from severe limitations. Laser cooling of atoms and molecules largely relies on the internal level structure of the species being cooled. As a result, only a small number of elements and a tiny number of molecules can be cooled this way. In the case of micromirrors, the problem lies in the engineering of micromirrors that need to satisfy a large number of constraints|these include a high mechanical Q-factor, high reflectivity and very good optical quality, weak coupling to the substrate, etc.|in order to enable efficient cooling. During the course of this thesis, I will draw these two sides of laser cooling closer together by means of a single, generically applicable scattering theory that can be used to explain the interaction between light and matter at a very general level. I use this 'transfer matrix' formalism to explore the use of the retarded dipole-dipole interaction as a means of both enhancing the efficiency of micromirror cooling systems and rendering the laser cooling of atoms and molecules less species selective. In particular, I identify the 'external cavity cooling' mechanism, whereby the use of an optical memory in the form of a resonant element (such as a cavity), outside which the object to be cooled sits, can potentially lead to the construction of fully integrated optomechanical systems and even two-dimensional arrays of translationally cold atoms, molecules or even micromirrors. The concept of an optical memory is a very general one, and use it to link together mechanisms that would otherwise appear disparate, including the cavity cooling of atoms and cooling mechanisms based on the non-adiabatic following of atomic populations. A fully vectorial three-dimensional scattering theory including the effects of such a memory is also presented and used to explore several different experimentally-realisable cooling configurations

Reducing the expense of ear wax

Ear wax is one of the commonest presenting complaints both in Ear Nose and Throat surgery and in General Practice. The commonest treatment by far given for this condition is Arachis oil (Cerumol®). Results from various studies however show that this appears not to be the most effective treatment and that cheaper options exist which may drastically reduce the costs incurred by the Health Department in this respect. We hereby outline the advantages of the use of 0.9% saline drops in the treatment of ear wax.peer-reviewe

Selectable linear or quadratic coupling in an optomechanical system

There has been much interest recently in the analysis of optomechanical systems incorporating dielectric nanoor microspheres inside a cavity field.We analyze here the situation when one of the mirrors of the cavity itself is also allowed to move.We reveal that the interplay between the two oscillators yields a cross-coupling that results in, e.g., appreciable cooling and squeezing of the motion of the sphere, despite its nominal quadratic coupling.We also discuss a simple modification that would allow this cross-coupling to be removed at will, thereby yielding a purely quadratic coupling for the sphere.A.X. thanks the Royal Commission for the Exhibition of 1851 for financial support. M.P. is supported by the UK EPSRC through a Career Acceleration Fellowship and the “New Directions for EPSRC Research Leaders” initiative (EP/G004759/1). Parts of the calculations were carried out using computational facilities funded by the European Regional Development Fund, Project ERDF-080.peer-reviewe

The rise of the quantum machines

Technological devices are getting ever smaller, but as they approach the scale at which quantum physics matters, our understanding of how they interact with their environment evaporates. The authors of this article explain how a better understanding of quantum thermodynamics could kick-start a new industrial revolution on the tiniest scale.peer-reviewe

The impact of the general data protection regulation on the financial services’ industry of small European states

This paper is based on the unpublished Thesis by Magri, A. (2018). An Evaluation of the Impact of GDPR on the Local Financial Services Industry. Banking and Finance, Department of Banking and Finance, Faculty of Economics, Management and Accountancy, University of Malta, supervised by Dr. Simon GrimaPurpose: With this paper we evaluate the impact and implications of the European Union (EU) General Data Protection Regulation (GDPR) on the Financial Services Industry in small European States; specifically Malta, Slovenia, Luxembourg, Lithuania, Latvia, Estonia and Cyprus. That is, countries within the EU having less than 3 million population. Design/methodology/approach: We collected our primary data by carrying out scheduled semi-structured interviews (using WhatsApp®, Messenger® and Skype®) with 63 participants who are working directly or indirectly with GDPR in financial services between November 2018 and April 2019. The interview was structured using two impact themes, ‘Trust, Standardisation and Reputation’ and ‘Training and ‘Resources’, with 18 statements under each theme to which participants were required to answer using a 5-point Likert-scale ranging from “Strongly Disagree” to “Strongly Agree”. To answer the research questions, the empirical data collected was subjected to statistical analysis using SPSS (Version 21) namely descriptive statistics and box plots and later MANOVA, while the qualitative data was analysed using the thematic approach. Findings: We found that overall, participants feel that although GDPR has increased the work load and costs, it has helped to improve the trust, standardisation and reputation of the institutions they represent. However, this comes with some repercussions from the data subjects who are not conversant with the regulation and are apprehensive by the consents required. Originality/value: Although, all States might be represented in the decision process, the larger States usually take over and sometimes dictate the final decision. The concept of proportionality in regulations is not clean and is not effectively managed, at the disadvantage of the smaller States. Therefore, this paper is important since it voices the cries of smaller States and allows for an understanding of the impact and implications of new regulations to smaller jurisdictions, in this case within the EU.peer-reviewe

Heat transport in harmonic oscillator systems with thermal baths : application to optomechanical arrays

We investigate the transport of phonons between N harmonic oscillators in contact with independent thermal baths and coupled to a common oscillator, and derive an expression for the steady state heat flow between the oscillators in the weak coupling limit.We apply these results to an optomechanical array consisting of a pair of mechanical resonators coupled to a single quantized electromagnetic field mode by radiation pressure as well as to thermal baths with different temperatures. In the weak coupling limit this system is shown to be equivalent to two mutually-coupled harmonic oscillators in contact with an effective common thermal bath in addition to their independent baths. The steady state occupation numbers and heat flows are derived and discussed in various regimes of interest.This work was supported by the COST Action MP1209 ‘Thermodynamics in the Quantum Regime’, and the Danish Council for Independent Research (Sapere Aude program).peer-reviewe

Out-of-equilibrium thermodynamics of quantum optomechanical systems

Weaddress the out-of-equilibrium thermodynamics of an isolated quantum system consisting of a cavity optomechanical device. Weexplore the dynamical response of the system when driven out of equilibrium by a sudden quench of the coupling parameter and compute analytically the full distribution of the work generated by the process.Weconsider linear and quadratic optomechanical coupling, where the cavity field is parametrically coupled to either the position or the square of the position of a mechanical oscillator, respectively. In the former case we find that the average work generated by the quench is zero, whilst the latter leads to a non-zero average value. Through fluctuations theorems we access the most relevant thermodynamical figures of merit, such as the free energy difference and the amount of irreversible work generated.Wethus provide a full characterization of the out-of-equilibrium thermodynamics in the quantum regime for nonlinearly coupled bosonic modes. Our study is the first due step towards the construction and full quantum analysis of an optomechanical machine working fully out of equilibrium.We are grateful to M Aspelmeyer for discussions and encouragements. This work was supported by the UK EPSRC (EP/L005026/1 and EP/J009776/1), the John Templeton Foundation (grant ID 43467), the EU Collaborative Project TherMiQ (Grant Agreement 618074), and the Royal Commission for the Exhibition of 1851. Part of this work was supported by COST Action MP1209 ‘Thermodynamics in the quantum regime’.peer-reviewe

Dynamical symmetries and crossovers in a three-spin system with collective dissipation

We consider the non-equilibrium dynamics of a simple system consisting of interacting spin-1/2 particles subjected to a collective damping. The model is close to situations that can be engineered in hybrid electro/opto-mechanical settings. Making use of large-deviation theory, we find a Gallavotti–Cohen symmetry in the dynamics of the system as well as evidence for the coexistence of two dynamical phases with different activity levels.Weshow that additional damping processes smooth out this behavior. Our analytical results are backed up by Monte Carlo simulations that reveal the nature of the trajectories contributing to the different dynamical phases.This work has been supported by the Royal Commission for the Exhibition of 1851, the UKEPSRC (EP/G004579/1, EP/J009776/1, EP/K029371/1 and EP/L005026/1), the John Templeton Foundation (Grant ID 43467), ERC Grant ESCQUMA(Grant Agreement 335266), and the EU Collaborative Project TherMiQ (Grant Agreement 618074). Part of this work was supported by the COST Action MP1209 ‘Thermodynamics in the quantum regime’.peer-reviewe

Efficient optomechanical cooling in one-dimensional interferometers

We present a scattering model which enables us to describe the mechanical force, including the velocity dependent component, exerted by light on polarizable massive objects in a general one-dimensional optical system. We show that the light field in an interferometer can be very sensitive to the velocity of a moving scatterer. We construct a new efficient cooling scheme, ‘external cavity cooling’, in which the scatterer, that can be an atom or a moving micromirror, is spatially separated from the cavity.This work was supported by the UK EPSRC (EP/E039839/1 and EP/E058949/1), by the CMMC collaboration within the EuroQUAM programme of the ESF, and by the National Office for Research and Technology (ERC HU 09 OPTOMECH) of Hungary.peer-reviewe

Cooling atoms, particles and polarisable objects using dissipative dipole forces

Optical cooling methods are generally applicable to a very restricted range of species. As a means of overcoming this problem, we explore the effect of the retarded interaction of any polarisable particle (an atom, a molecule or even a micromirror) with itself, similarly to cavity-mediated cooling. We use the transfer matrix method, extended to allow us to handle moving scatterers, to explore the most general configuration of a mobile particle interacting with any 1D combination of fixed optical elements. Remarkably, this model allows a solution in closed form for the force acting on the particle, without any a priori restriction on the nature of the particle.peer-reviewe