183 research outputs found
Laser cooling with a single laser beam and a planar diffractor
A planar triplet of diffraction gratings is used to transform a single laser
beam into a four-beam tetrahedral magneto-optical trap. This `flat' pyramid
diffractor geometry is ideal for future microfabrication. We demonstrate the
technique by trapping and subsequently sub-Doppler cooling 87Rb atoms to
30microKelvin.Comment: 3 pages, 4 figure
Extinction by Miscalculation:
Species at Risk Act, Sakinaw sockeye, Cultus sockeye, fisheries management, extinction.
A Digital Alkali Spin Maser
Self-oscillating atomic magnetometers, in which the precession of atomic
spins in a magnetic field is driven by resonant modulation, offer high
sensitivity and dynamic range. Phase-coherent feedback from the detected signal
to the applied modulation creates a resonant spin maser system, highly
responsive to changes in the background magnetic field. Here we show a system
in which the phase condition for resonant precession is met by digital signal
processing integrated into the maser feedback loop. This system uses a modest
chip-scale laser and mass-produced dual-pass caesium vapour cell and operates
in a 50 microtesla field, making it a suitable technology for portable
measurements of the geophysical magnetic field. We demonstrate a Cramer-Rao
lower bound-limited resolution of 50 fT at 1 s sampling cadence, and a sensor
bandwidth of 10 kHz. This device also represents an important class of atomic
system in which low-latency digital processing forms an integral part of a
coherently-driven quantum system.Comment: 12 pages, 5 figure
Apoptose regulierende Proteine und deren klinische Bedeutung beim Mantelzell-Lymphom : eine immunhistochemische Untersuchung
Immunhistochemische Studie über die prognostische Aussagekraft von fünf verschiedenen apoptose-assoziierten Proteine bei 93 Patienten mit einem Mantelzell-Lymphom
Single-laser, one beam, tetrahedral magneto-optical trap
We have realised a 4-beam pyramidal magneto-optical trap ideally suited for
future microfabrication. Three mirrors split and steer a single incoming beam
into a tripod of reflected beams, allowing trapping in the four-beam overlap
volume. We discuss the influence of mirror angle on cooling and trapping,
finding optimum efficiency in a tetrahedral configuration. We demonstrate the
technique using an ex-vacuo mirror system to illustrate the previously
inaccessible supra-plane pyramid MOT configuration. Unlike standard pyramidal
MOTs both the pyramid apex and its mirror angle are non-critical and our MOT
offers improved molasses free from atomic shadows in the laser beams. The MOT
scheme naturally extends to a 2-beam refractive version with high optical
access. For quantum gas experiments, the mirror system could also be used for a
stable 3D tetrahedral optical lattice.Comment: 8 pages, 6 figures, 2 movie
Orientational effects on the amplitude and phase of polarimeter signals in double resonance atomic magnetometry
Double resonance optically pumped magnetometry can be used to measure static magnetic fields with high sensitivity by detecting a resonant atomic spin response to a small oscillating field perturbation. Determination of the resonant frequency yields a scalar measurement of static field (B_0) magnitude. We present calculations and experimental data showing that the on-resonance polarimeter signal of light transmitted through an atomic vapour in arbitrarily oriented may be modelled by considering the evolution of alignment terms in atomic polarisation. We observe that the amplitude and phase of the magnetometer signal are highly dependent upon B_0 orientation, and present precise measurements of the distribution of these parameters over the full 4 pi solid angle
Utilising diffractive optics towards a compact, cold atom clock
Laser cooled atomic samples have resulted in profound advances in precision metrology [1], however the technology is typically complex and bulky. In recent publications we described a micro-fabricated optical element, that greatly facilitates miniaturisation of ultra-cold atom technology [2], [3], [4], [5]. Portable devices should be feasible with accuracy vastly exceeding that of equivalent room-temperature technology, with a minimal footprint. These laser cooled samples are ideal for atomic clocks. Here we will discuss the implementation of our micro-fabricated diffractive optics towards building a robust, compact cold atom clock
A feed-forward measurement scheme for periodic noise suppression in atomic magnetometry
We present an unshielded, double-resonance magnetometer in which we have implemented a feed-forward measurement scheme in order to suppress periodic magnetic noise arising from, and correlated with, the mains electricity alternating current line. The technique described here uses a single sensor to track ambient periodic noise and feed forward to suppress it in a subsequent measurement. This feed forward technique has shown significant noise suppression of electrical mains-noise features of up to 22 dB under the fundamental peak at 50 Hz, 3 dB at the first harmonic (100 Hz), and 21 dB at the second harmonic (150 Hz). This technique is software based, requires no additional hardware, and is easy to implement in an existing magnetometer
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