New strategy to transform the quality of careers education, advice and guidance for young people

This paper, based on David's experience of having been directly involved in careers work for young people over 35 years, offers some personal suggestions about what should be included in the forthcoming strategy for careers education and guidance. The aim of this strategy should be to ensure that the careers support that young people experience provides them with the help that they need to progress successfully through learning and into work. It should prepare them for lives and careers where they will have to navigate a complex and challenging landscape of education, training and employment

The irreducible photon

In recent years it has become evident that the primary concept of the photon has multiple interpretations, with widely differing secondary connotations. Despite the all-pervasive nature of this concept in science, some of the ancillary properties with which the photon is attributed in certain areas of application sit uneasily alongside those invoked in other areas. Certainly the range of applications extends far beyond what was envisaged in the original conception, now entering subjects extending from elementary particle physics and cosmology through to spectroscopy, statistical mechanics and photochemistry. Addressing this diverse context invites the question: What is there, that it is possible to assert as incontrovertibly true about the photon? Which properties are non-controversial, if others are the subject of debate? This paper describes an attempt to answer these questions, establishing as far as possible an irreducible core of what can rightly be asserted about the photon, and setting aside some of what often is, but should never be so asserted. Some of the more bewildering difficulties and differences of interpretation owe their origin to careless descriptions, highlighting a need to guard semantic precision; although simplifications are frequently and naturally expedient for didactic purposes, they carry the risk of becoming indelible. Focusing on such issues, the aim is to identify how much or how little about the photon can be regarded as truly non-controversial

Chiral separation and twin-beam photonics

It is well-known that, in a homogeneous fluid medium, most optical means that afford discrimination between molecules of opposite handedness are intrinsically weak effects. The reason is simple: the wide variety of origins for differential response commonly feature real or virtual electronic transitions that break a parity condition. Despite being electric dipole allowed, they manifest the chirality of the material in which they occur by breaking a selection rule that would otherwise preclude the simultaneous involvement of magnetic dipole or electric quadrupole forms of coupling. Although the latter are typically weaker than electric dipole effects by several orders of magnitude, it is the involvement of these weak forms of interaction that are responsible for chiral sensitivity. There have been a number of attempts to cleverly exploit novel optical configurations to enhance the relative magnitude – and hence potentially the efficiency – of chiral discrimination. The prospect of success in any such venture is enticing, because of the huge impact that such an advance might be expected to have in the health, food and medical sectors. Some of these proposals have utilized mirror reflection, and others surface plasmon coupling, or optical binding methods. Several recent works in the literature have drawn attention to a further possibility: the deployment of optical beam interference as a means to achieve chiral separations of sizeable extent. In this paper the underlying theory is fully developed to identify the true scope and limitations of such an approach

Optical control of excited-state lifetimes

Electronic excitation of particles in fluorescent materials can now be controlled using laser-assisted energy-transfer techniques

Photon-based and classical descriptions in nanophotonics: a review

The centrality of the photon concept in modern physics is strongly evident in wide spheres of photonics and nanophotonics. Despite the resilience and persistence of earlier classical representations, there are numerous optical features and phenomena that only truly photon-based descriptions of theory can properly address. It is crucial to cast theory in terms of observables, and in this respect the quantum theory of light engages most directly and pragmatically with experiment. No other theory adequately reconciles the discreteness in energy of optical quanta, with their characteristic quantum mechanical delocalization in space. Examples of the distinctiveness of a photonic representation are to be found in nonclassical optical correlations; intensity fluctuations and phase; polarization, spin, and information content; measures of optical chirality; near-field interactions; and plasmonics. Increasingly, links between these fundamental properties and features are proving significant in the context of nanoscale interactions. Yet, even as new technologies are being built on the framework of modern photonics, a number of difficult questions surrounding the nature of the photon still remain. Both in its flourishing applications and in matters of fundamental entity, the photon is still a subject very much at the heart of current research

Energy harvesting: a review of the interplay between structure and mechanism

The science of energy harvesting has recently undergone radical change, with the advent of new materials exploiting mechanisms fundamentally different from those of traditional solar cells. Utilizing principles that are in many cases acquired from breakthroughs in molecular photobiology, the introduction of a range of new synthetic polymers, multichromophore arrays and nanoparticle-based materials heralds a marked resurgence of interest, a shift of focus and heightened expectations in the science of light-harvesting. The interplay between structure and mechanism significantly impinges upon issues extending from fundamental theory to the principles of energy-harvesting materials design. Understanding and exploiting the principles allows materials to be engineered that can harness absorbed energy with heightened efficiency. Two of the key areas of application are dendrimers and rare-earth doped solids