95 research outputs found
Stabilisation of an optical transition energy via nuclear Zeno dynamics in quantum dot-cavity systems
We investigate the effect of nuclear spins on the phase shift and
polarisation rotation of photons scattered off a quantum dot-cavity system. We
show that as the phase shift depends strongly on the resonance energy of an
electronic transition in the quantum dot, it can provide a sensitive probe of
the quantum state of nuclear spins that broaden this transition energy. By
including the electron-nuclear spin coupling at a Hamiltonian level within an
extended input-output formalism, we show how a photon scattering event acts as
a nuclear spin measurement, which when rapidly applied leads to an inhibition
of the nuclear spin dynamics via the quantum Zeno effect, and a corresponding
stabilisation of the optical resonance. We show how such an effect manifests in
the intensity autocorrelation of scattered photons, whose
long-time bunching behaviour changes from quadratic decay for low photon
scattering rates (weak laser intensities), to ever slower exponential decay for
increasing laser intensities as optical measurements impede the nuclear spin
evolution.Comment: 8 pages, 3 figure
Synthesis and cryogenic spectroscopy of narrow-diameter single-wall carbon nanotubes
AbstractWe report chemical vapor deposition and cryogenic photoluminescence studies of narrow-diameter single-wall carbon nanotubes. Our systematic study of synthesis parameters identifies means to control the average length, diameter, and areal density of carbon nanotubes grown on silica substrates. Using synthesis conditions that favor the growth of carbon nanotubes with sub-nanometer diameters, we fabricate samples with spatially isolated suspended nanotubes ideally suited for optical studies. Photoluminescence spectroscopy of individual nanotubes reveals two classes: spectrally broad and narrow single-peak emission at the temperature of liquid helium. The latter class with spectral line widths down to the resolution limit of our spectrometer of 40 μeV indicates that exciton coherence in carbon nanotubes can be substantially improved by controlling the growth conditions and utilized in sources of indistinguishable single photons
Quantum modulation of a coherent state wavepacket with a single electron spin
The interaction of quantum objects lies at the heart of fundamental quantum
physics and is key to a wide range of quantum information technologies.
Photon-quantum-emitter interactions are among the most widely studied.
Two-qubit interactions are generally simplified into two quantum objects in
static well-defined states . In this work we explore a fundamentally new
dynamic type of spin-photon interaction. We demonstrate modulation of a
coherent narrowband wavepacket with another truly quantum object, a quantum dot
with ground state spin degree of freedom. What results is a quantum modulation
of the wavepacket phase (either 0 or {\pi} but no values in between), a new
quantum state of light that cannot be described classically.Comment: Supplementary Information available on reques
On the monotone stability approach to BSDEs with jumps: Extensions, concrete criteria and examples
We show a concise extension of the monotone stability approach to backward
stochastic differential equations (BSDEs) that are jointly driven by a Brownian
motion and a random measure for jumps, which could be of infinite activity with
a non-deterministic and time inhomogeneous compensator. The BSDE generator
function can be non convex and needs not to satisfy global Lipschitz conditions
in the jump integrand. We contribute concrete criteria, that are easy to
verify, for results on existence and uniqueness of bounded solutions to BSDEs
with jumps, and on comparison and a-priori -bounds. Several
examples and counter examples are discussed to shed light on the scope and
applicability of different assumptions, and we provide an overview of major
applications in finance and optimal control.Comment: 28 pages. Added DOI
https://link.springer.com/chapter/10.1007%2F978-3-030-22285-7_1 for final
publication, corrected typo (missing gamma) in example 4.1
Determination of the LOQ in real-time PCR by receiver operating characteristic curve analysis: application to qPCR assays for Fusarium verticillioides and F. proliferatum
Real-time PCR (qPCR) is the principal technique for the quantification of pathogen biomass in host tissue, yet no generic methods exist for the determination of the limit of quantification (LOQ) and the limit of detection (LOD) in qPCR. We suggest using the Youden index in the context of the receiver operating characteristic (ROC) curve analysis for this purpose. The LOQ was defined as the amount of target DNA that maximizes the sum of sensitivity and specificity. The LOD was defined as the lowest amount of target DNA that was amplified with a false-negative rate below a given threshold. We applied this concept to qPCR assays for Fusarium verticillioides and Fusarium proliferatum DNA in maize kernels. Spiked matrix and field samples characterized by melting curve analysis of PCR products were used as the source of true positives and true negatives. On the basis of the analysis of sensitivity and specificity of the assays, we estimated the LOQ values as 0.11Â pg of DNA for spiked matrix and 0.62Â pg of DNA for field samples for F. verticillioides. The LOQ values for F. proliferatum were 0.03Â pg for spiked matrix and 0.24Â pg for field samples. The mean LOQ values correspond to approximately eight genomes for F. verticillioides and three genomes for F. proliferatum. We demonstrated that the ROC analysis concept, developed for qualitative diagnostics, can be used for the determination of performance parameters of quantitative PCR
Electron transfer dynamics in semiconductor–chromophore–polyoxometalate catalyst photoanodes
Pottery production and trade in the Banda zone, Indonesia: the Kei tradition in its spatial and historical context
This paper provides the first comprehensive description of pottery production in the Kei islands of eastern Indonesia, based on field data collected mainly in 1981 and on Museum collections in the UK and The Netherlands. The account is situated in what we know of the dynamics of trading systems that existed in the Moluccan islands between 1500 and 2000. Kei pottery is widely thought to be the successor of a tradition established in the Banda islands that was extinguished with the 1621 Dutch massacre of Bandanese, but re-established at several sites in the Kei islands by Bandanese migrants after this date. These claims are critically examined using ethnographic and archaeological data, and an attempt made to compare the production and trading patterns of pottery in the ‘Banda zone’ before and after 1621
A survey of time consistency of dynamic risk measures and dynamic performance measures in discrete time: LM-measure perspective
A new existence result for second-order BSDEs with quadratic growth and their applications
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