Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The most accurate optical single-ion clock worldwide

10.02.2016

Atomic clock experts from the Physikalisch-Technische Bundesanstalt (PTB) are the first research group in the world to have built an optical single-ion clock which attains an accuracy which had only been predicted theoretically so far. Their optical ytterbium clock achieved a relative systematic measurement uncertainty of 3 E-18. The results have been published in the current issue of the scientific journal "Physical Review Letters".

Atomic clock experts from the Physikalisch-Technische Bundesanstalt (PTB) are the first research group in the world to have built an optical single-ion clock which attains an accuracy which had only been predicted theoretically so far.


Radio-frequency trap of PTB's optical ytterbium single-ion clock. (Photo: PTB)


Schematic representation: Measuring the influence of thermal ambient radiation on the frequency of the trapped ion: the "clock laser" (blue beam) excites the trapped ion (yellow) with a special pulse sequence. The resonance frequency of the ion is influenced by infrared radiation (here by an infrared laser, red beam). This can be measured by means of the clock laser. (Fig.: PTB)

As early as 1981, Hans Dehmelt, who was to be awarded a Nobel prize later, had already developed the basic notions of how to use an ion kept in a high-frequency trap to build a clock which could attain the – then unbelievably low – relative measurement uncertainty in the range of 1E-18.

Ever since, an increasing number of research groups worldwide have been trying to achieve this with optical atomic clocks (either based on single trapped ions or on many neutral atoms). The PTB scientists are the first to have reached the finishing line using a single-ion clock. Their optical ytterbium clock achieved a relative systematic measurement uncertainty of 3 E-18. The results have been published in the current issue of the scientific journal "Physical Review Letters".

The definition and realization of the SI unit of time, the second, is currently based on cesium atomic clocks. Their "pendulum" consists of atoms which are excited into resonance by microwave radiation (1E10 Hz). It is regarded as certain that a future redefinition of the SI second will be based on an optical atomic clock. These have a considerably higher excitation frequency (1E14 to 1E15 Hz), which makes them much more stable and more accurate than cesium clocks.

The accuracy now achieved with the ytterbium clock is approximately a hundred times better than that of the best cesium clocks. To develop their clock, the researchers from PTB exploited particular physical properties of Yb+. This ion has two reference transitions which can be used for an optical clock.

One of these transitions is based on the excitation into the so-called "F state" which, due to its extremely long natural lifetime (approx. 6 years), provides exceptionally narrow resonance. In addition, due to the particular electronic structure of the F state, the shifts of the resonance frequency caused by electric and magnetic fields are exceptionally small.

The other reference transition (into the D3/2 state) exhibits higher frequency shifts and is therefore used as a sensitive "sensor" to optimize and control the operating conditions. Another advantage is that the wavelengths of the lasers required to prepare and excite Yb+ are in a range in which reliable and affordable semiconductor lasers can be used.

The decisive factor for the last leap in accuracy was the combination of two measures: firstly, a special procedure was conceived for the excitation of the reference transition. With this procedure, the "light shift" of the resonance frequency caused by the exciting laser is measured separately.

This information is then used to immunize the excitation of the reference transition against the light shift and its possible variation. Secondly, the frequency shift caused by the thermal infrared radiation of the environment (which is relatively small for the F state of Yb+ anyway) was determined with a measurement uncertainty of only 3 %. For this purpose, the frequency shift caused by laser light and its intensity distribution at the ion's location were measured at four different wavelengths in the infrared range.

Another particular property of the F state of Yb+ is the strong dependence of the state energy on the value of the fine-structure constant (the elementary fundamental constant of electromagnetic interaction) and on the anisotropy effects in the interaction between electrons and certain potential forms of the so-called dark matter which plays an important part in the present cosmologic standard model. Comparisons between Yb+ clocks and other highly accurate optical clocks are currently probably the most promising way of verifying theories from this area of "new physics" in the lab.
(es/ptb)

Contact:
Dr. Christian Tamm, Senior Scientist, Department 4.4, Subject Area "Optical frequency standards", phone: +49 (0)531 5924415, e-mail: christian.tamm@ptb.de

Scientific publication:
N. Huntemann, C. Sanner, B. Lipphardt, Chr. Tamm, E. Peik: Single ion atomic clock with 3 E-18 uncertainty. Phys. Rev. Lett. 116, 063001 (2016)

Weitere Informationen:

http://www.ptb.de/cms/en/presseaktuelles/journalisten/press-releases/press-relea...

Dipl.-Journ. Erika Schow | idw - Informationsdienst Wissenschaft

More articles from Earth Sciences:

nachricht From volcano's slope, NASA instrument looks sky high and to the future
27.04.2017 | NASA/Goddard Space Flight Center

nachricht Penn researchers quantify the changes that lightning inspires in rock
27.04.2017 | University of Pennsylvania

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Bare bones: Making bones transparent

27.04.2017 | Life Sciences

Study offers new theoretical approach to describing non-equilibrium phase transitions

27.04.2017 | Physics and Astronomy

From volcano's slope, NASA instrument looks sky high and to the future

27.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>