A solid state light-matter interface at the single photon level

Coherent and reversible mapping of quantum information between light and matter is an important experimental challenge in quantum information science. In particular, it is a decisive milestone for the implementation of quantum networks and quantum repeaters. So far, quantum interfaces between light and atoms have been demonstrated with atomic gases, and with single trapped atoms in cavities. Here we demonstrate the coherent and reversible mapping of a light field with less than one photon per pulse onto an ensemble of 10 millions atoms naturally trapped in a solid. This is achieved by coherently absorbing the light field in a suitably prepared solid state atomic medium. The state of the light is mapped onto collective atomic excitations on an optical transition and stored for a pre-programmed time up of to 1 mu s before being released in a well defined spatio-temporal mode as a result of a collective interference. The coherence of the process is verified by performing an interference experiment with two stored weak pulses with a variable phase relation. Visibilities of more than 95% are obtained, which demonstrates the high coherence of the mapping process at the single photon level. In addition, we show experimentally that our interface allows one to store and retrieve light fields in multiple temporal modes. Our results represent the first observation of collective enhancement at the single photon level in a solid and open the way to multimode solid state quantum memories as a promising alternative to atomic gases.Comment: 5 pages, 5 figures, version submitted on June 27 200

The Circadian Response of Intrinsically Photosensitive Retinal Ganglion Cells

Intrinsically photosensitive retinal ganglion cells (ipRGC) signal environmental light level to the central circadian clock and contribute to the pupil light reflex. It is unknown if ipRGC activity is subject to extrinsic (central) or intrinsic (retinal) network-mediated circadian modulation during light entrainment and phase shifting. Eleven younger persons (18–30 years) with no ophthalmological, medical or sleep disorders participated. The activity of the inner (ipRGC) and outer retina (cone photoreceptors) was assessed hourly using the pupil light reflex during a 24 h period of constant environmental illumination (10 lux). Exogenous circadian cues of activity, sleep, posture, caffeine, ambient temperature, caloric intake and ambient illumination were controlled. Dim-light melatonin onset (DLMO) was determined from salivary melatonin assay at hourly intervals, and participant melatonin onset values were set to 14 h to adjust clock time to circadian time. Here we demonstrate in humans that the ipRGC controlled post-illumination pupil response has a circadian rhythm independent of external light cues. This circadian variation precedes melatonin onset and the minimum ipRGC driven pupil response occurs post melatonin onset. Outer retinal photoreceptor contributions to the inner retinal ipRGC driven post-illumination pupil response also show circadian variation whereas direct outer retinal cone inputs to the pupil light reflex do not, indicating that intrinsically photosensitive (melanopsin) retinal ganglion cells mediate this circadian variation

Comparing Notes: Recording and Criticism

This chapter charts the ways in which recording has changed the nature of music criticism. It both provides an overview of the history of recording and music criticism, from the advent of Edison’s Phonograph to the present day, and examines the issues arising from this new technology and the consequent transformation of critical thought and practice

Wider Still and Wider: British Music Criticism since the Second World War

This chapter provides the first historical examination of music criticism in Britain since the Second World War. In the process, it also challenges the simplistic prevailing view of this being a period of decline from a golden age in music criticism

The Gender Paradox: Criticism of Women and Women as Critics

In May 2014 a storm erupted in the British classical music world when five established male critics fat-shamed Irish mezzo-soprano Tara Erraught, who was performing Octavian in Der Rosenkavalier at Covent Garden. Instead of focusing upon Erraught’s technique or interpretation, the critics ridiculed her physique. Writing in the Financial Times Andrew Clark referred to Erraught as ‘a chubby bundle of puppy-fat’; Michael Church in The Independent and Rupert Christiansen in The Telegraph both described her as ‘dumpy’; Andrew Clements in The Guardian called her ‘stocky’; and Richard Morrison in The Times characterised her as ‘unbelievable, unsightly and unappealing’. Although these sexist comments drew widespread condemnation, they are symptomatic of a centuries-old tendency for empowered male critics to fail to produce objective assessments of female musicians

Critiquing the Canon: The Role of Criticism in Canon Formation

Music critics wield great power. Their writing influences public opinion and contributes to how audiences receive works. They focus attention upon specific works and musicians, thus justifying these as most worthy of public recognition and debate. They help works to achieve repeat performances, and thereby to establish their places within the performing canon. In the age of recorded sound, they influence sales and affect charts. Although some claim that with the recent rise of ubiquitous digital critical commentary (much of it amateur) professional critics have lost their traditional authority, online criticism continues to exercise considerable sway. In a very real way, critics have been – and continue to be – the gatekeepers of the canon. As Roy Shuker has observed, ‘popular music critics … function as significant gatekeepers and as arbiters of taste’