31 research outputs found
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
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
6 W, 1 kHz linewidth, tunable continuous-wave near-infrared laser
A modified Coherent 899-21 titanium sapphire laser is injection locked to
produce 6-6.5 W of single-frequency light at 852 nm. After closed-loop
amplitude control and frequency stabilization to a high-finesse cavity, it
delivers 4-4.5 W with <1 kHz linewidth at the output of a single-mode fiber.
The laser is tunable from about 700-1000 nm; up to 8 W should be possible at
750-810 nm.Comment: Published version with details and references added. 3 page
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
Atom interferometers with scalable enclosed area
Bloch oscillations (i.e., coherent acceleration of matter waves by an optical
lattice) and Bragg diffraction are integrated into light-pulse atom
interferometers with large momentum splitting between the interferometer arms,
and hence enhanced sensitivity. Simultaneous acceleration of both arms in the
same internal states suppresses systematic effects, and simultaneously running
a pair of interferometers suppresses the effect of vibrations. Ramsey-Bord\'e
interferometers using four such Bloch-Bragg-Bloch (BBB) beam splitters exhibit
15% contrast at 24 splitting, the largest so far ( is the
photon momentum); single beam splitters achieve 88. The prospects for
reaching 100s of and applications like gravitational wave sensors are
discussed.Comment: 4 pages, 5 figure