14,704 research outputs found
Lasing in Strong Coupling
An almost ideal thresholdless laser can be realized in the strong-coupling
regime of light-matter interaction, with Poissonian fluctuations of the field
at all pumping powers and all intensities of the field. This ideal scenario is
thwarted by quantum nonlinearities when crossing from the linear to the
stimulated emission regime, resulting in a universal jump in the second order
coherence, which measurement could however be used to establish a standard of
lasing in strong coupling.Comment: 5 pages, 2 figure
How sensitive is a neutrino factory to the angle ?
We consider the impact of non-standard interactions of neutrinos (NSI) on the
determination of neutrino mixing parameters at a neutrino factory using
\pnu{e}\to\pnu{\mu} ``golden channels'' for the measurement of .
We show how a small residual NSI leads to a drastic loss in sensitivity in
, of up to two orders of magnitude. This can be somewhat overcome
if two baselines are combined.Comment: 4 pages, 3 figure
Spontaneous, collective coherence in driven, dissipative cavity arrays
We study an array of dissipative tunnel-coupled cavities, each interacting
with an incoherently pumped two-level emitter. For cavities in the lasing
regime, we find correlations between the light fields of distant cavities,
despite the dissipation and the incoherent nature of the pumping mechanism.
These correlations decay exponentially with distance for arrays in any
dimension but become increasingly long ranged with increasing photon tunneling
between adjacent cavities. The interaction-dominated and the
tunneling-dominated regimes show markedly different scaling of the correlation
length which always remains finite due to the finite photon trapping time. We
propose a series of observables to characterize the spontaneous build-up of
collective coherence in the system.Comment: 9 pages, 4 figures, including supplemental material (with 4 pages, 1
figure). This is a shorter version with some modifications in the
supplemental material (a gap in the proof was closed and calculations
significantly generalized and improved
Strong-coupling of quantum dots in microcavities
We show that strong-coupling (SC) of light and matter as it is realized with
quantum dots (QDs) in microcavities differs substantially from the paradigm of
atoms in optical cavities. The type of pumping used in semiconductors yields
new criteria to achieve SC, with situations where the pump hinders, or on the
contrary, favours it. We analyze one of the seminal experimental observation of
SC of a QD in a pillar microcavity [Reithmaier et al., Nature (2004)] as an
illustration of our main statements.Comment: Substantially revised version. The major change is in the analysis of
one of the seminal experiment of the field, that shows the excellent
quantitative agreement with the theory. Full details, especially all
concerning Fermi statistics (still present in previous versions), are now to
be presented elsewhere. To be published in Phys. Rev. Lett. 101 (2008
An exploration of executive women's experiences of coaching and mentoring: an Interpretative Phenomenological Analysis study
The slow pace of womenâs advancement to senior levels in organisations is an ongoing topical debate. Resolving this issue through appropriate developmental support interventions is the subject of much discussion. An understanding of the use of coaching and mentoring to address this individual, organisational and societal problem is, however, underresearched in a UK context, and more widely.
In the coaching and mentoring literature there is limited research concerning the voice of the coachee/mentee and even less research relating to executive women. This study sought to address this deficiency and explore the experiences of executive women who have been coached and mentored, in order to gain an understanding of the role of these interventions and how they assisted the womenâs development. Qualitative research was conducted using an Interpretative Phenomenological
Analysis (IPA) methodology and involved semi-structured interviews with twelve executive women, all of whom worked at senior levels in UK organisations. The data were subsequently analysed using Smith, Flowers and Larkinâs (2009) interpretive framework.
The findings highlight the positive impact of coaching and mentoring on the careers of the executive women in this study. Mentoring provided early career and psychosocial support, while coaching provided later support and challenge that encouraged the development of skills, authenticity and
identity; aided coping with and adapting to the work environment; and in some cases assisted with broader life decisions. The participantsâ subsequent commitment to coach and mentor others was a further outcome of this research. This study contributes not only to understanding the context of a coaching assignment involving executive women, the âexperienceâ of coaching and mentoring, and the importance of the coaching relationship, but also to the application of such learning to assist
others. The implications of this research expand knowledge and provide new insights to add to the limited literature on coaching and mentoring executive women in the UK
Climbing the Jaynes-Cummings ladder by photon counting
We present a new method to observe direct experimental evidence of
Jaynes--Cummings nonlinearities in a strongly dissipative cavity quantum
electrodynamics system, where large losses compete with the strong light-matter
interaction. This is a highly topical problem, particularly for quantum dots in
microcavities where transitions from higher rungs of the Jaynes--Cummings
ladder remain to be evidenced explicitly. We compare coherent and incoherent
excitations of the system and find that resonant excitation of the detuned
emitter make it possible to unambiguously evidence few photon quantum
nonlinearities in currently available experimental systems.Comment: 4 pages, 4 figures (color online). Updated bb
On q-Deformed Supersymmetric Classical Mechanical Models
Based on the idea of quantum groups and paragrassmann variables, we presenta
generalization of supersymmetric classical mechanics with a deformation
parameter dealing with the case. The
coordinates of the -superspace are a commuting parameter and a
paragrassmann variable , where . The generator and
covariant derivative are obtained, as well as the action for some possible
superfields.Comment: No figures, 14 pages, Latex, revised versio
Finding the Higgs Boson through Supersymmetry
The study of displaced vertices containing two b--jets may provide a double
discovery at the Large Hadron Collider (LHC): we show how it may not only
reveal evidence for supersymmetry, but also provide a way to uncover the Higgs
boson necessary in the formulation of the electroweak theory in a large region
of the parameter space. We quantify this explicitly using the simplest minimal
supergravity model with bilinear breaking of R-parity, which accounts for the
observed pattern of neutrino masses and mixings seen in neutrino oscillation
experiments.Comment: 7 pages, 7 figures. Final version to appear at PRD. Discussion and
results were enlarge
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