arXiv:1107.3169 · Physical Review Letters

Rydberg Spectroscopy in an Optical Lattice: Blackbody Thermometry for Atomic Clocks

Vitalii D Ovsiannikov, Andrei Derevianko, Kurt Gibble

Published Aug 23, 2011• 63 citations

Abstract

We show that optical spectroscopy of Rydberg states can provide accurate in situ thermometry at room temperature. Transitions from a metastable state to Rydberg states with principal quantum numbers of 25-30 have 200 times larger fractional frequency sensitivities to blackbody radiation than the strontium clock transition. We demonstrate that magic-wavelength lattices exist for both strontium and ytterbium transitions between the metastable and Rydberg states. Frequency measurements of Rydberg transitions with 10(-16) accuracy provide 10 mK resolution and yield a blackbody uncertainty for the clock transition of 10(-18).

DOI: 10.1103/physrevlett.107.093003

Related papers

Bestimmung des Einflusses thermischer Strahlung auf eine optische Strontium-Gitteruhr

Thomas Middelmann

Optical clocks have the potential to be 100 times more accurate than current best cesium atomic clocks within a fraction of the averaging time.This corresponds to a fractional uncertainty of the clock frequency on the level of 10 -18 and requires highaccuracy knowledge of systematic frequency shifts, such that they can be avoided or corrected for.In strontium optical lattice clocks an ensemble of ultracold strontium atoms is conned in an optical lattice, to allow for spectroscopy of the reference transition 5s 2 1 S 0 5s5p 3 P 0 in the Lamb-Dicke regime.The by far largest systematic frequency shift of the strontium clock transition is caused by its high sensitivity to blackbody radiation (BBR).The knowledge of the resulting frequency shift limited the achievable clock uncertainty to about 1 × 10 -16 .In this thesis for the rst time an experimental approach was followed, to determine the sensitivity of the strontium clock transition to blackbody radiation.At an environmental temperature of 300 K the resulting frequency shift corresponds to 2.277 8(23) Hz.The achieved uncertainty contributes with 5 × 10 -18 to the fractional systematic uncertainty of the clock frequency.The determination is based on a precision measurement of the dierence of static polarizabilities of the two clock states ∆α dc = α(5s5p 3 P 0 ) -α(5s 2 1 S 0 ) = 4.078 73(11) × 10 -39 Cm 2 /V.For this the dc Stark shift of the clock transition has been measured in the accurately known electric eld of a precision plate capacitor, which has been developed in this work.The attained static polarizability dierence ∆α dc corresponds to the rst term of a power series of the sensitivity to BBR.Higher orders are accumulated as dynamic part of the BBR shift.Which has been modelled using ∆α dc and experimental data for other atomic properties.To interrogate the ultracold atoms in the electric eld a novel transport technique has been developed, which uses the magic wavelength (813 nm) optical lattice to convey the atoms.For this, the interference pattern is translated together with the foci of the far-detuned lattice beams, by simultaneous translation of the lattice optics.In this way ultracold atoms have been transported within 250 ms over 5 cm, or several Rayleigh ranges respectively without signicant atom loss or heating.In the course of this work the rst frequency measurement with the strontium lattice clock of Physikalisch-Technischen Bundesanstalt (PTB) has been performed.The frequency of the 87 Sr clock transition was measured to be 429 228 004 229 872.9(5)Hz.The strontium lattice clock itself contributed with 1.5 × 10 -16 to the overall fractional uncertainty.Furthermore the thermal radiation eld in a cryogenic blackbody environment was modelled and a draft of a corresponding environment of the atoms was designed, which is suitable to be implemented in the strontium lattice clock of PTB.

Jan 1, 20130 citations

Development of an Apparatus for a Strontium Optical Lattice Optical Frequency Standard

Ian R. Hill

Accurate time keeping is critical to the function and advancement of many human endeavours. Atomic clocks based on a microwave transition in atomic Cs have served as primary frequency standards to realise the SI second since their formal adoption in 1967. State-of-the-art, laser cooled, Cs fountains now routinely operate with fractional frequency uncertainties below the 10⁻¹⁵ level in laboratories throughout the world. Over the last decade, efforts to build frequency standards based on optical transitions have come to fruition and potential inaccuracies below the 10⁻¹⁷ level have been demonstrated. Such standards point to the future of time keeping and much development is being pursued to realise the potential of these 'next generation' optical clocks. One such approach, on which this work focusses, relies on a 'magic' wavelength optical lattice trap to provide (almost) Doppler- and recoil-free confinement of atoms during clock interrogation. At this 'magic' wavelength, light induced perturbation of the clock states is equal and so cancels precisely. This thesis describes the design and implementation of an optical lattice frequency standard apparatus based on 88Sr held in a 1D optical lattice. A review of the development of atomic frequency metrology is given from a historical viewpoint and the technology and limitations of current methods discussed. To tackle the blackbody radiation shift, which currently presents the greatest limitation to the Sr lattice clock, imposing at the 10⁻¹⁶ level, a scheme to measure the blackbody radiation shift coefficient at the 10⁻¹⁷ level is developed. Techniques to laser cool and trap atomic strontium are described and the implementation detailed. All laser systems required for clock operation are described including the design and implementation of extended-cavity diode lasers for precision spectroscopy. Details relevant to the eventual operation of the apparatus are discussed.

Jun 1, 20123 citations

Measurement of the differential polarizability of the 698 nm clock transition of strontium for evaluation of optical lattice clocks

Thomas Middelmann, Stephan Falke, Christian Lisdat +1 more

A modification to a successfull technique to measure static differential polarizabilities of ultracold atoms and molecules is presented. Ultracold atoms are trapped in a magic wavelength optical lattice and transported into the field of a precision capacitor. The change of the transition frequency induced by the applied field, which is controlled to better than 10-4, is measured. For atomic clocks, the difference of the static polarizabilies of ground and excited state is closely related to their response to a blackbody radiation field, which is a significant contribution to the uncertainty budget of many atomic clocks.

Conference on Precision Electromagnetic MeasurementsJul 1, 20120 citations

Carrier thermometry of cold ytterbium atoms in an optical lattice clock

Chengyin Han, Min Zhou, Xiaohang Zhang +5 more

The ultracold atomic gas serving as the quantum reference is a key part of an optical lattice clock, and the temperature of atoms in the optical lattice affects the uncertainty and instability of the optical lattice clocks. Since the carrier spectrum of the clock transition in the lattices reflects the thermal dynamics of cold atoms, the temperature of atoms can be extracted from the carrier spectrum in a non-magic wavelength lattice of ytterbium optical clocks. Furthermore, the temperatures obtained from the carrier spectra are in good agreement with the results obtained by the time-of-flight method and thermometry based on the sideband spectrum. In addition, the heating effects caused by the lattice laser are studied on the basis of the sample temperatures.

Scientific ReportsMay 15, 20188 citations

Primary quantum thermometry of mm-wave blackbody radiation via induced state transfer in Rydberg states of cold atoms

Noah Schlossberger, Andrew P. Rotunno, Stephen Eckel +14 more

Rydberg states of alkali-metal atoms are highly sensitive to electromagnetic radiation in the GHz-to-THz regime because their transitions have large electric dipole moments. Consequently, environmental blackbody radiation (BBR) can couple Rydberg states together at µ s timescales. Here, we track the BBR-induced transfer of a prepared Rydberg state to its neighbors and use the evolution of these state populations to characterize the BBR field at the relevant wavelengths, primarily at 130 GHz. We use selective field ionization readout of Rydberg states with principal quantum number n ∼ 30 in Rb 85 and substantiate our ionization signal with a theoretical model. With this detection method, we measure the associated blackbody-radiation-induced time dynamics of these states, reproduce the results with a simple semiclassical population transfer model, and demonstrate that this measurement is temperature sensitive with a statistical sensitivity to the fractional temperature uncertainty of 0.09 Hz − 1 / 2 , corresponding to 26 K Hz − 1 / 2 at room temperature. This represents a calibration-free SI-traceable temperature measurement, for which we calculate a systematic fractional temperature uncertainty of 0.006, corresponding to 2 K at room temperature when used as a primary temperature standard.

arXiv:2410.11694Physical Review ResearchJan 23, 202521 citations

Tackling the blackbody shift in a strontium optical lattice clock

Thomas Middelmann, Christian Lisdat, Stephan Falke +3 more

A major obstacle for optical clocks is the frequency shift due to black body radiation. We discuss how one can tackle this problem in an optical lattice clock; in our case 87-Sr: firstly, by a measurement of the dc Stark shift of the clock transition and, secondly, by interrogating the atoms in a cryogenic environment. Both approaches rely on transporting ultracold atoms over several cm within a probe cycle. We evaluate this approach of mechanically moving the optical lattice and conclude that it is feasible to transport the atoms over 50 mm within 300 ms. With this transport a dc Stark shift measurement will allow to reduce the contribution of the blackbody radiation to the fractional uncertainty below 2 * 10^-17 at room temperature by improving the shift coefficient known only from atomic structure calculations up to now. We propose a cryogenic environment at 77 K that will reduce this contribution to few parts in 10^-18.

arXiv:1009.2017Sep 10, 20102 citations