324 research outputs found
A generalized Ramsey excitation scheme with suppressed light shift
We experimentally investigate a recently proposed optical excitation scheme
[V.I. Yudin et al., Phys. Rev. A 82, 011804(R)(2010)] that is a generalization
of Ramsey's method of separated oscillatory fields and consists of a sequence
of three excitation pulses. The pulse sequence is tailored to produce a
resonance signal which is immune to the light shift and other shifts of the
transition frequency that are correlated with the interaction with the probe
field. We investigate the scheme using a single trapped 171Yb+ ion and excite
the highly forbidden 2S1/2-2F7/2 electric-octupole transition under conditions
where the light shift is much larger than the excitation linewidth, which is in
the Hertz range. The experiments demonstrate a suppression of the light shift
by four orders of magnitude and an immunity against its fluctuations.Comment: 5 pages, 4 figure
High-accuracy optical clock based on the octupole transition in 171Yb+
We experimentally investigate an optical frequency standard based on the 467
nm (642 THz) electric-octupole reference transition 2S1/2(F=0) -> F7/2(F=3) in
a single trapped 171Yb+ ion. The extraordinary features of this transition
result from the long natural lifetime and from the 4f136s2 configuration of the
upper state. The electric quadrupole moment of the 2F7/2 state is measured as
-0.041(5) e(a0)^2, where e is the elementary charge and a0 the Bohr radius. We
also obtain information on the differential scalar and tensorial components of
the static polarizability and of the probe light induced ac Stark shift of the
octupole transition. With a real-time extrapolation scheme that eliminates this
shift, the unperturbed transition frequency is realized with a fractional
uncertainty of 7.1x10^(-17). The frequency is measured as 642 121 496 772
645.15(52) Hz.Comment: 5 pages, 4 figure
Atomic clocks with suppressed blackbody radiation shift
We develop a nonstandard concept of atomic clocks where the blackbody
radiation shift (BBRS) and its temperature fluctuations can be dramatically
suppressed (by one to three orders of magnitude) independent of the
environmental temperature. The suppression is based on the fact that in a
system with two accessible clock transitions (with frequencies v1 and v2) which
are exposed to the same thermal environment, there exists a "synthetic"
frequency v_{syn} (v1-e12 v2) largely immune to the BBRS. As an example, it is
shown that in the case of ion 171Yb+ it is possible to create a clock in which
the BBRS can be suppressed to the fractional level of 10^{-18} in a broad
interval near room temperature (300\pm 15 K). We also propose a realization of
our method with the use of an optical frequency comb generator stabilized to
both frequencies v1 and v2. Here the frequency v_{syn} is generated as one of
the components of the comb spectrum and can be used as an atomic standard.Comment: 5 pages, 2 figure
Berry Phase Generation and Measurement in a Single Trapped Ion
In this work, we propose a new design of an ion trap which can enable us to
generate state specific Berry phase in a single trapped ion. Such a design will
enable us to study the physics at the boundary of abelian and non-abelian
symmetries and can also have significant impact in quantum computation
Improved limits on the coupling of ultralight bosonic dark matter to photons from optical atomic clock comparisons
We present improved constraints on the coupling of ultralight bosonic dark
matter to photons based on long-term measurements of two optical frequency
ratios. In these optical clock comparisons, we relate the frequency of the
electric-octupole (E3)
transition in Yb to that of the electric-quadrupole (E2) transition of the same ion, and
to that of the transition in Sr.
Measurements of the first frequency ratio are
performed via interleaved interrogation of both transitions in a single ion.
The comparison of the single-ion clock based on the E3 transition with a
strontium optical lattice clock yields the second frequency ratio
. By constraining oscillations of the
fine-structure constant with these measurement results, we improve
existing bounds on the scalar coupling of ultralight dark matter to
photons for dark matter masses in the range of about . These results constitute an improvement by
more than an order of magnitude over previous investigations for most of this
range. We also use the repeated measurements of
to improve existing limits on a linear
temporal drift of and its coupling to gravity.Comment: 7 pages, 5 figure
Evaluation of a Sr+ 88 Optical Clock with a Direct Measurement of the Blackbody Radiation Shift and Determination of the Clock Frequency
We report on an evaluation of an optical clock that uses the S21/2→D25/2 transition of a single Sr+88 ion as the reference. In contrast to previous work, we estimate the effective temperature of the blackbody radiation that shifts the reference transition directly during operation from the corresponding frequency shift and the well-characterized sensitivity to thermal radiation. We measure the clock output frequency against an independent Yb+171 ion clock, based on the S21/2(F=0)→F27/2(F=3) electric octupole (E3) transition, and determine the frequency ratio with a total fractional uncertainty of 2.3×10-17. Relying on a previous measurement of the Yb+171 (E3) clock frequency, we find the absolute frequency of the Sr+88 clock transition to be 444 779 044 095 485.277(59) Hz. Our result reduces the uncertainty by a factor of 3 compared with the previously most accurate measurement and may help to resolve so far inconsistent determinations of this value. We also show that for three simultaneously interrogated Sr+88 ions, the increased number causes the expected improvement of the short-term frequency instability of the optical clock without degrading its systematic uncertainty
- …