88 research outputs found
Nuclear Spin Effects in Optical Lattice Clocks
We present a detailed experimental and theoretical study of the effect of
nuclear spin on the performance of optical lattice clocks. With a state-mixing
theory including spin-orbit and hyperfine interactions, we describe the origin
of the - clock transition and the differential g-factor between
the two clock states for alkaline-earth(-like) atoms, using Sr as an
example. Clock frequency shifts due to magnetic and optical fields are
discussed with an emphasis on those relating to nuclear structure. An
experimental determination of the differential g-factor in Sr is
performed and is in good agreement with theory. The magnitude of the tensor
light shift on the clock states is also explored experimentally. State specific
measurements with controlled nuclear spin polarization are discussed as a
method to reduce the nuclear spin-related systematic effects to below
10 in lattice clocks.Comment: 13 pages, 12 figures, submitted to PR
Optical atomic coherence at the one-second time scale
Highest resolution laser spectroscopy has generally been limited to single
trapped ion systems due to rapid decoherence which plagues neutral atom
ensembles. Here, precision spectroscopy of ultracold neutral atoms confined in
a trapping potential shows superior optical coherence without any deleterious
effects from motional degrees of freedom, revealing optical resonance
linewidths at the hertz level with an excellent signal to noise ratio. The
resonance quality factor of 2.4 x 10^{14} is the highest ever recovered in any
form of coherent spectroscopy. The spectral resolution permits direct
observation of the breaking of nuclear spin degeneracy for the 1S0 and 3P0
optical clock states of 87Sr under a small magnetic bias field. This optical
NMR-like approach allows an accurate measurement of the differential Lande
g-factor between the two states. The optical atomic coherence demonstrated for
collective excitation of a large number of atoms will have a strong impact on
quantum measurement and precision frequency metrology.Comment: in press (2006
Systematic study of the Sr clock transition in an optical lattice
With ultracold Sr confined in a magic wavelength optical lattice, we
present the most precise study (2.8 Hz statistical uncertainty) to-date of the
- optical clock transition with a detailed analysis of
systematic shifts (20 Hz uncertainty) in the absolute frequency measurement of
429 228 004 229 867 Hz. The high resolution permits an investigation of the
optical lattice motional sideband structure. The local oscillator for this
optical atomic clock is a stable diode laser with its Hz-level linewidth
characterized across the optical spectrum using a femtosecond frequency comb.Comment: 4 pages, 4 figures, 1 tabl
Recommended from our members
Contribution of Thermal Noise to Frequency Stability of Rigid Optical Cavity via Hertz-Linewidth Lasers
We perform detailed studies of state-of-the-art laser stabilization to high finesse optical cavities, revealing fundamental mechanical thermal noise-related length fluctuations. We compare the frequency noise of lasers tightly locked to the resonances of a variety of rigid Fabry-Perot cavities of differing lengths and mirror substrate materials. The results are in agreement with the theoretical model proposed in K. Numata, A. Kemery, and J. Camp [Phys. Rev. Lett. 93, 250602 (2004)]. The results presented here on the fundamental limits of FP references will impact planning and construction of next generation ultrastable optical cavities
Coherent optical phase transfer over a 32-km fiber with 1-s instability at
The phase coherence of an ultrastable optical frequency reference is fully
maintained over actively stabilized fiber networks of lengths exceeding 30 km.
For a 7-km link installed in an urban environment, the transfer instability is
at 1-s. The excess phase noise of 0.15 rad, integrated from
8 mHz to 25 MHz, yields a total timing jitter of 0.085 fs. A 32-km link
achieves similar performance. Using frequency combs at each end of the
coherent-transfer fiber link, a heterodyne beat between two independent
ultrastable lasers, separated by 3.5 km and 163 THz, achieves a 1-Hz linewidth.Comment: 4 pages, 4 figure
Recommended from our members
Experimental Implementation of Optical Clockwork without Carrier-Envelope Phase Control
We demonstrate an optical clockwork without camer-envelope phase control using sum-frequency generation between a CW optical parametric oscillator at 3.39 μm and a modelocked Tisapphire laser with dominant spectral peaks at 834 and 670 nm
Recommended from our members
Optical Clockwork without Carrier-Envelope Phase Control
We demonstrate optical clockwork without carrier-envelope phase control using sum-frequency generation between a cw optical parametric oscillator at 3.39 μm and a mode-locked Ti:sapphire laser with dominant spectral peaks at 834 nm and 670 nm
Recommended from our members
Subfemtosecond Timing Jitter between Two Independent, Actively Synchronized, Mode-Locked Lasers
With the implementation of a fast-bandwidth servo, along with improved laser construction and associated better passive stability, we have achieved subfemtosecond relative timing jitter between two independent, actively synchronized, mode-locked Ti:sapphire lasers. Timing jitter of 0.58 fs is obtained with a 160-Hz observation bandwidth over several seconds. Within a 2-MHz observation bandwidth, the timing jitter is 1.75 fs. Excellent repeatability and rapid speed in setting an arbitrary time delay between two pulses are also demonstrated
- …