40 research outputs found
Application of optical single-sideband laser in Raman atom interferometry
A frequency doubled I/Q modulator based optical single-sideband (OSSB) laser
system is demonstrated for atomic physics research, specifically for atom
interferometry where the presence of additional sidebands causes parasitic
transitions. The performance of the OSSB technique and the spectrum after
second harmonic generation are measured and analyzed. The additional sidebands
are removed with better than 20 dB suppression, and the influence of parasitic
transitions upon stimulated Raman transitions at varying spatial positions is
shown to be removed beneath experimental noise. This technique will facilitate
the development of compact atom interferometry based sensors with improved
accuracy and reduced complexity
One-dimensional photonic band gaps in optical lattices
The phenomenon of photonic band gaps in one-dimensional optical lattices is
reviewed using a microscopic approach. Formally equivalent to the transfer
matrix approach in the thermodynamic limit, a microscopic model is required to
study finite-size effects, such as deviations from the Bragg condition.
Microscopic models describing both scalar and vectorial light are proposed, as
well as for two- and three-level atoms. Several analytical results are compared
to experimental data, showing a good agreement
RealFill: Reference-Driven Generation for Authentic Image Completion
Recent advances in generative imagery have brought forth outpainting and
inpainting models that can produce high-quality, plausible image content in
unknown regions, but the content these models hallucinate is necessarily
inauthentic, since the models lack sufficient context about the true scene. In
this work, we propose RealFill, a novel generative approach for image
completion that fills in missing regions of an image with the content that
should have been there. RealFill is a generative inpainting model that is
personalized using only a few reference images of a scene. These reference
images do not have to be aligned with the target image, and can be taken with
drastically varying viewpoints, lighting conditions, camera apertures, or image
styles. Once personalized, RealFill is able to complete a target image with
visually compelling contents that are faithful to the original scene. We
evaluate RealFill on a new image completion benchmark that covers a set of
diverse and challenging scenarios, and find that it outperforms existing
approaches by a large margin. See more results on our project page:
https://realfill.github.ioComment: Project page: https://realfill.github.i
Cold Atom Space Payload Atmospheric Drag Mission (CASPA-ADM)
To gain better understanding of the upper atmospheric dynamics requires more accurate determination of the mass density distribution in the thermosphere. Improved measurements of drag, by means of satellite accelerometery, can be used to more precisely determine this distribution. In addition, atmospheric drag in Low Earth Orbit (LEO) is particularly of interest for climate modelling, weather forecasting and satellite orbit prediction. RAL Space, Teledyne-e2v and the University of Birmingham are developing a Cold Atom Space Payload Atmospheric Drag Mission (CASPA-ADM). The aim of the project, supported by the UK Centre for Earth Observation Instrumentation (CEOI), is to develop a technology demonstrator based on Cold Atom Interferometry (CAI) to take sensitive measurements of atmospheric drag. The underlying CAI technology has been previously flown on the Chinese Space Station, the International Space Station, and in sounding rockets. However, it has not yet been used as the fundamental sensor technology in a free flight space mission. The team is producing a space-suitable accelerometer that can be embedded in small satellites such as 16U CubeSats and are addressing the engineering challenges associated with space qualification and miniaturisation, while keeping the performance level of systems with larger Size, Weight and Power (SWaP)
A Dielectric Metasurface Optical Chip for the Generation of Cold Atoms
Compact and robust cold atom sources are increasingly important for quantum
research, especially for transferring cutting-edge quantum science into
practical applications. In this letter, we report on a novel scheme that
utilizes a metasurface optical chip to replace the conventional bulky optical
elements used to produce a cold atomic ensemble with a single incident laser
beam, which is split by the metasurface into multiple beams of the desired
polarization states. Atom numbers and temperatures (about 35 K)
of relevance to quantum sensing are achieved in a compact and robust fashion.
Our work highlights the substantial progress towards fully integrated cold atom
quantum devices by exploiting metasurface optical chips, which may have great
potential in quantum sensing, quantum computing and other areas
Magneto-optical trapping in a near-suface borehole
Borehole gravity sensing can be used in a number of applications to measure features around a well, including rock-type change mapping and determination of reservoir porosity. Quantum technology gravity sensors, based on atom interferometry, have the ability to offer increased survey speeds and reduced need for calibration. While surface sensors have been demonstrated in real world environments, significant improvements in robustness and reductions to radial size, weight, and power consumption are required for such devices to be deployed in boreholes. To realise the first step towards the deployment of cold atom-based sensors down boreholes, we demonstrate a borehole-deployable magneto-optical trap, the core package of many cold atom-based systems. The enclosure containing the magneto-optical trap itself had an outer radius of (60 ± 0.1) mm at its widest point and a length of (890 ± 5) mm. This system was used to generate atom clouds at 1 m intervals in a 14 cm wide, 50 m deep borehole, to simulate how in-borehole gravity surveys are performed. During the survey, the system generated, on average, clouds of (3.0 ± 0.1) × 105 87Rb atoms with the standard deviation in atom number across the survey observed to be as low as 8.9 × 104
Magneto-optical trapping in a near-surface borehole
Borehole gravity sensing can be used in a number of applications to measure
features around a well including rock-type change mapping and determination of
reservoir porosity. Quantum technology gravity sensors based on atom
interferometry have the ability to offer increased survey speeds and reduced
need for calibration. While surface sensors have been demonstrated in real
world environments, significant improvements in robustness and reductions to
radial size, weight, and power consumption are required for such devices to be
deployed in boreholes. To realise the first step towards the deployment of cold
atom-based sensors down boreholes, we demonstrate a borehole-deployable
magneto-optical trap, the core package of many cold atom-based systems. The
enclosure containing the magneto-optical trap itself had an outer radius of
() mm at its widest point and a length of () mm. This system
was used to generate atom clouds at 1 m intervals in a 14 cm wide, 50 m deep
borehole, to simulate an in-borehole gravity surveys are performed. During the
survey the system generated on average clouds of (3.0
Rb atoms with the standard deviation in atom number across the survey
observed to be as low as