16 research outputs found
Large-momentum-transfer atom interferometers with rad-accuracy using Bragg diffraction
Large-momentum-transfer~(LMT) atom interferometers using elastic Bragg
scattering on light waves are among the most precise quantum sensors to date.
To advance their accuracy from the mrad to the rad regime, it is necessary
to understand the rich phenomenology of the Bragg interferometer, which differs
significantly from that of a standard two-mode interferometer. We develop an
analytic model for the interferometer signal and demonstrate its accuracy using
comprehensive numerical simulations. Our analytic treatment allows the
determination of the atomic projection noise limit of an LMT Bragg
interferometer, and provides the means to saturate this limit. It affords
accurate knowledge of the systematic phase errors as well as their suppression
by two orders of magnitude down to a few using appropriate
light pulse parameters.Comment: 7 pages, 5 figures,comments welcome!; Assembled supplemental material
together with mansucrip
Universal atom interferometer simulation of elastic scattering processes
In this article, we introduce a universal simulation framework covering all regimes of matter-wave light-pulse elastic scattering. Applied to atom interferometry as a study case, this simulator solves the atom-light diffraction problem in the elastic case, i.e., when the internal state of the atoms remains unchanged. Taking this perspective, the light-pulse beam splitting is interpreted as a space and time-dependent external potential. In a shift from the usual approach based on a system of momentum-space ordinary differential equations, our position-space treatment is flexible and scales favourably for realistic cases where the light fields have an arbitrary complex spatial behaviour rather than being mere plane waves. Moreover, the solver architecture we developed is effortlessly extended to the problem class of trapped and interacting geometries, which has no simple formulation in the usual framework of momentum-space ordinary differential equations. We check the validity of our model by revisiting several case studies relevant to the precision atom interferometry community. We retrieve analytical solutions when they exist and extend the analysis to more complex parameter ranges in a cross-regime fashion. The flexibility of the approach, the insight it gives, its numerical scalability and accuracy make it an exquisite tool to design, understand and quantitatively analyse metrology-oriented matter-wave interferometry experiments. © 2020, The Author(s)
Precision inertial sensing with quantum gases
Quantum sensors based on light-pulse atom interferometers allow for
high-precision measurements of inertial and electromagnetic forces such as the
accurate determination of fundamental constants as the fine structure constant
or testing foundational laws of modern physics as the equivalence principle.
These schemes unfold their full performance when large interrogation times
and/or large momentum transfer can be implemented. In this article, we
demonstrate how precision interferometry can benefit from the use of
Bose-Einstein condensed sources when the state of the art is challenged. We
contrast systematic and statistical effects induced by Bose-Einstein condensed
sources with thermal sources in three exemplary science cases of Earth- and
space-based sensors.Comment: 13 page
V-Edge: Virtual Edge Computing as an Enabler for Novel Microservices and Cooperative Computing
As we move from 5G to 6G, edge computing is one of the concepts that needs
revisiting. Its core idea is still intriguing: instead of sending all data and
tasks from an end user's device to the cloud, possibly covering thousands of
kilometers and introducing delays that are just owed to limited propagation
speed, edge servers deployed in close proximity to the user, e.g., at some 5G
gNB, serve as proxy for the cloud. Yet this promising idea is hampered by the
limited availability of such edge servers. In this paper, we discuss a way
forward, namely the virtual edge computing (V-Edge) concept. V-Edge bridges the
gap between cloud, edge, and fog by virtualizing all available resources
including the end users' devices and making these resources widely available
using well-defined interfaces. V-Edge also acts as an enabler for novel
microservices as well as cooperative computing solutions. We introduce the
general V-Edge architecture and we characterize some of the key research
challenges to overcome, in order to enable wide-spread and even more powerful
edge services
Genomes of multicellular algal sisters to land plants illuminate signaling network evolution
Zygnematophyceae are the algal sisters of land plants. Here we sequenced four genomes of filamentous Zygnematophyceae, including chromosome-scale assemblies for three strains of Zygnema circumcarinatum. We inferred traits in the ancestor of Zygnematophyceae and land plants that might have ushered in the conquest of land by plants: expanded genes for signaling cascades, environmental response, and multicellular growth. Zygnematophyceae and land plants share all the major enzymes for cell wall synthesis and remodifications, and gene gains shaped this toolkit. Co-expression network analyses uncover gene cohorts that unite environmental signaling with multicellular developmental programs. Our data shed light on a molecular chassis that balances environmental response and growth modulation across more than 600 million years of streptophyte evolution
Influence of environmentally affected hole-transport layers on spatial homogeneity and charge-transport dynamics of organic solar cells
After the efficiency of organic photovoltaic (OPV) cells achieved more than
10%, the control of stability and degradation mechanisms of solar cells became
a prominent task. The improvement of device efficiency due to incorporation of
a hole-transport layer (HTL) in bulk-heterojunction solar cells has been
extensively reported. However, the most widely used HTL material, PEDOT:PSS is
frequently suspected to be the dominating source for devices instability under
environmental conditions. Thereby effects like photooxidation and electrode
corrosion are often reported to shorten device lifetime. However, often in
environmental device studies, the source of degradation, whether being from the
HTL, the active layer or the metal cathode are rather difficult to distinguish,
because the external diffusion of oxygen and water affects all components. In
this study, different HTLs, namely prepared from traditional PEDOT:PSS and also
two types of molybdenum trioxide (MoO3), are exposed to different environments
such as oxygen, light or humidity, prior to device finalization under inert
conditions. This allows investigating any effects within the HTL and from
reactions at its interface to the indium-tin-oxide electrode or the active
layer. The surface and bulk chemistry of the exposed HTL has been monitored and
discussed in context to the observed device physics, dynamic charge transport
and spatial performance homogeneity of the according OPV device. The results
show that merely humidity-exposure of the HTL leads to decreased device
performance for PEDOT:PSS, but also for one type of the tested MoO3. The losses
are related to the amount of absorbed water in the HTL, inducing loss of active
area in terms of interfacial contact. The device with PEDOT:PSS HTL after humid
air exposure showed seriously decreased photocurrent by micro-delamination of
swelling/shrinkage of the hygroscopic layer
Influence of Environmentally Affected Hole-Transport Layers on Spatial Homogeneity and Charge-Transport Dynamics of Organic Solar Cells
After
organic photovoltaic (OPV) cells achieved efficiency of more than
10%, the control of stability and degradation mechanisms of solar
cells became a prominent task. The increase of device efficiency due
to incorporation of a hole-transport layer (HTL) in bulk-heterojunction
solar cells has been extensively reported. However, the most widely
used HTL material, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)
(PEDOT:PSS), is frequently suspected to be the dominating source for
device instability under environmental conditions. Thereby, effects
like photooxidation and electrode corrosion are often reported to
shorten device lifetime. However, often in environmental device studies,
the source of degradation, whether being from the HTL, the active
layer, or the metal cathode is rather difficult to distinguish because
the external diffusion of oxygen and water affects all components.
In this study, different HTLs, namely, those prepared from traditional
PEDOT:PSS and also two types of molybdenum trioxide (MoO<sub>3</sub>) are exposed to different environments, such as oxygen, light, or
humidity, prior to device finalization under inert conditions. This
allows investigating any effects within the HTL and from reactions
at its interface to the indium tin oxide electrode or the active layer.
The surface and bulk chemistry of the exposed HTL has been monitored
and discussed in context to the observed device physics, dynamic charge
transport, and spatial performance homogeneity of the corresponding
OPV device. The results show that merely humidity exposure of the
HTL leads to decreased device performance for PEDOT:PSS, but also
for one type of the tested MoO<sub>3</sub>. The losses are related
to the amount of absorbed water in the HTL, inducing loss of active
area in terms of interfacial contact. The device with PEDOT:PSS HTL
after humid air exposure showed seriously decreased photocurrent by
microdelamination of swelling/shrinkage of the hygroscopic layer.
The colloidal MoO<sub>3</sub> with water-based precursor solution
presents slight decay of solar cell performance, also here caused
by swelling/shrinking reaction, but by a combination of in-plane particle
contact and resistance scaling with particle expansion. However, the
device with quasi-continuous and alcohol-based MoO<sub>3</sub> showed
unharmed stable electrical performance