227 research outputs found
Atom interferometry in an optical cavity
We propose and demonstrate a new scheme for atom interferometry, using light
pulses inside an optical cavity as matter wave beamsplitters. The cavity
provides power enhancement, spatial filtering, and a precise beam geometry,
enabling new techniques such as low power beamsplitters (), large momentum transfer beamsplitters with modest power, or new
self-aligned interferometer geometries utilizing the transverse modes of the
optical cavity. As a first demonstration, we obtain Ramsey-Raman fringes with
contrast and measure the acceleration due to gravity, , to
resolution in a Mach-Zehnder geometry.
We use cesium atoms in the compact mode volume (
waist) of the cavity and show trapping of atoms in higher transverse
modes. This work paves the way toward compact, high sensitivity, multi-axis
interferometry.Comment: 5 pages, 6 figure
Atom Interferometry with up to 24-Photon-Momentum-Transfer Beam Splitters
We present up to 24-photon Bragg diffraction as a beam splitter in
light-pulse atom interferometers to achieve the largest splitting in momentum
space so far. Relative to the 2-photon processes used in the most sensitive
present interferometers, these large momentum transfer beam splitters increase
the phase shift 12-fold for Mach-Zehnder (MZ-) and 144-fold for Ramsey-Borde
(RB-) geometries. We achieve a high visibility of the interference fringes (up
to 52% for MZ or 36% for RB) and long pulse separation times that are possible
only in atomic fountain setups. As the atom's internal state is not changed,
important systematic effects can cancel.Comment: New introduction. 4 pages, 4 figure
Extended cavity diode lasers with tracked resonances
We present a painless, almost-free upgrade to present extended cavity diode
lasers (ECDLs), which improves the long term mode-hop free performance by
stabilizing the resonance of the internal cavity to the external cavity. This
stabilization is based on the observation that the frequency or amplitude noise
of the ECDL is lowest at the optimum laser diode temperature or injection
current. Thus, keeping the diode current at the level where the noise is lowest
ensures mode-hop free operation within one of the stable regions of the mode
chart, even if these should drift due to external influences. This method can
be applied directly to existing laser systems without modifying the optical
setup. We demonstrate the method in two ECDLs stabilized to vapor cells at 852
nm and 895 nm wavelength. We achieve long term mode-hop free operation and low
noise at low power consumption, even with an inexpensive non-antireflection
coated diode.Comment: 5 pages, 6 figure
Nanosecond electro-optical switching with a repetition rate above 20MHz
We describe an electro-optical switch based on a commercial electro-optic
modulator (modified for high-speed operation) and a 340V pulser having a rise
time of 2.2ns (at 250V). It can produce arbitrary pulse patterns with an
average repetition rate beyond 20MHz. It uses a grounded-grid triode driven by
transmitting power transistors. We discuss variations that enable analog
operation, use the step-recovery effect in bipolar transistors, or offer other
combinations of output voltage, size, and cost.Comment: 3 pages, 3 figures. Minor change
The implementation of Malay language education policy and the linguistic landscape in Malaysia
This ethnographic research uses the applied linguistic landscape of Ben-Rafael (2009) to examine the choices of language practice (Spolsky, 2009) reflected through 459 Romanised names of the company on an island in Malaysia named Labuan. One of the outcomes of this study shows Malaysians are basically bilingual and about half of the names of the company are bilingual. However, the use of Malay language in naming the companies on the island is low though the Malay language is the national language of the country and the Malaysian government has implemented the Malay language education policy since independence in 1957. There are only 13% of company names presented in pure Malay language comparing to those in pure English (45%) and in code-mixing of Malay language and English or other languages (42%). Besides a low percentage of using the Malay language in the company names, incorrect uses of the language were identified. The study suggests the Malaysian government specifically the local government considers the company name written in both Malay language and English instead of merely in the Malay language when it comes to approving the application of new company licenses
Noise-Immune Conjugate Large-Area Atom Interferometers
We present a pair of simultaneous conjugate Ramsey-Borde atom interferometers
(SCI) using large (20\hbar k)-momentum transfer (LMT) beam splitters, where
\hbar k is the photon momentum. Simultaneous operation allows for common-mode
rejection of vibrational noise. This allows us to surpass the enclosed
space-time area of previous interferometers with a splitting of 20\hbar k by a
factor of 2,500. Among applications, we demonstrate a 3.4 ppb resolution in the
fine structure constant and discuss tests of fundamental laws of physics.Comment: 4 pages revtex, 5 figure
Atom Interferometry tests of the isotropy of post-Newtonian gravity
We present a test of the local Lorentz invariance of post-Newtonian gravity
by monitoring Earth's gravity with a Mach-Zehnder atom interferometer that
features a resolution of about 8*10^(-9)g/Hz^(1/2), the highest reported thus
far. Expressed within the standard model extension (SME) or Nordtvedt's
anisotropic universe model, the analysis limits four coefficients describing
anisotropic gravity at the ppb level and three others, for the first time, at
the 10ppm level. Using the SME we explicitly demonstrate how the experiment
actually compares the isotropy of gravity and electromagnetism.Comment: Added outlook, corrected typos; to appear in PRL. 4 pages, 3 figure
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