At first glance, it seems like a utopia, detail-obsessed physicist: Why in the world it needs a clock, in 1000 billion years, just a second wrong? 1000 billion years, which is almost 100 times as long as the universe is old. At least for the time change this coming weekend, a precise clock is rather insignificant.

Nevertheless, for years the stated goal of some scientists to develop such a precise clock. While today’s atomic clocks are based on the physics of the atomic electron shell, is to use the new PM physical effects in the atomic nucleus. In simplified terms, case is a nuclear solid than the airy electron. Therefore, a Kernuhr could less easily by interference factors such as electromagnetic fields or thermal radiation from the clock, and should therefore allow, at least theoretically, a far more accurate measurement of time as an atomic clock of today’s design.

For the science that would be of great importance, starting with the search for dark matter in the universe up to a Test of Einstein’s General theory of relativity. “Generally speaking, the time unit “second” is playing in the International system has a crucial role,” says Jacques Morel, head of the laboratory Photonics, time and frequency at the Swiss Federal Institute of Metrology (Metas). “The more we can realize the second, the more accurate also a lot of other units can be realized.”

Thorium nuclei as a clock for the Kernuhr

As the clock of a Kernuhr be used for atomic nuclei of the isotope Thorium-229, an artificially in special laboratories manufactured Material. As the only nucleus of an atom of Thorium-229 has the property that it can be using a laser from the ground state to an excited energy state called the isomer state. In the case of all other atomic nuclei, the excitation requires the isomer state with higher energy than they can with today’s lasers ready. The vibrations of the light radiated by an excited Thorium in the core after a certain time, should be very stable and the Kernuhr a very constant and fast stroke confer – with more than a quadrillion (1000 million million) hits per second.

The Problem: The exact energy of the isomer state of Thorium-229 was not yet known. Therefore, it was also unclear what frequency or “color” would have to have a Laser exactly to the Thorium core is to stimulate, and to a Thorium-Kernuhr build. Now two teams of researchers have succeeded in a crucial measurement, as they report in the journal “Nature”. Accordingly, the Laser used to excite the Thorium nucleus would emit light having a wavelength of about 149,7 nano-meters, reports a research group led by Benedict Seiferle from the Ludwig-Maximilians-University (LMU) in Munich. This is a wavelength range, the high-energy ultra-violet Laser can achieve. On a similar level to the Japanese Team led by Takahiko Masuda, University of Okayama came.

“In the experiments by Seiferle, and colleagues is the most important result of the more accurate value for the transition energy in the core,” says Ekkehard Peik Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Germany, has developed the concept of a Thorium-clock more than a decade ago, together with his colleague Christian Tamm. “It was in the last twelve years, worldwide, only a precise measurement. The new result is a factor three more precise.” Thus, the search interval for the correct laser is reduced in frequency significantly. The Experiment of Masuda and colleagues, while not directly relevant to the watches. “But it will allow to understand the structure of this unusual atomic nucleus better.”

We hope that in five to six years, a functional Kernuhr developed.Benedict Seiferle, Ludwig-Maximilians-University, Munich, Germany

According to Morel, Metas, the results are “for the development of a Kernuhr certainly an important step”. This does not mean, however, that one could define the second soon. “First, you have to build more of these nuclear clocks, and these clocks can then compare to each other, in order to confirm the measurements.” The will need for many years.

further research on each case. The project “Thorium Nuclear Clock” under the leadership of Thorsten Schumm of the Vienna University of technology, Co-author of both the “Nature”publications, will be funded with an ERC Synergy Grant from the European Research Council in the amount of around CHF 15 million. Also Peik from the PTB is involved in the project, as well as the group around Peter Thirolf, of the LMU Munich, and Is also-ferle is a member of. “The next step is the excitation of the core with a Laser is in any case”, says Seiferle. “We hope that in the next five to six years, a conceptually functional Kernuhr developed.” Whether this Kernuhr will then achieve the predicted accuracy was, however, questionable. “That would not be necessary, however, to the benefits of the core exploit.”

would the high-precision clocks, for example, for the Verification of Einstein’s General theory of relativity. This suggests that masses affect not only the space but also the time. As the time passes near large masses more slowly. However, the gravity on earth compared to super massive Black holes, extremely weak. Watches will only be affected minimally. Therefore, it takes a tremendous accurate timepiece to check Einstein’s theory here.

More Vermessungdes Geoid

Also, you could measure the so-called Geoid of the earth to be more precise: This is the area on which the force of gravity (Gravitation) around the globe is the same. To do this, you would have to walk with a mobile Kernuhr of the earth and its clock rate with a stationary clock compare. The time difference is then a direct measure for the Geoid. Also, for a more precise satellite navigation system, more accurate clocks are essential. Because the more accurate the clocks tick in the satellite and on the ground, the more precisely the runtime of the signals between the satellite and the earth can be measured. The position determination is based.

With a Kernuhr the question could perhaps clarify whether certain constants of nature really are constant. Should change, for example, the strength of the electromagnetic interaction or nuclear power with time, would react to the transition energy from the ground state to the isomer state of Thorium-229 enormously sensitive to it. Consequently, the would be the nucleus of an atom excited emit light at a slightly different frequency. Therefore, the core clocks should tick with the time is minimal, unlike conventional atomic clocks. Similar sensitive the excited core state of Thorium would react, 229 on the existence of certain candidates for the long sought after, but still mysterious cosmic dark matter.

in addition to the core clocks optical atomic clocks are promising candidates for the next Generation of high-precision timepieces. With today’s atomic clocks of cesium atoms by microwave excited used, the clock frequency in the range of several Gigahertz. In optical atomic clocks, the clock frequency is more than 10’000-fold higher. Thus, they allow for an approximately 100-fold higher accuracy. There are different variants with different atoms or ions as a reference, for example, with Strontium atoms or Ytterbium ions. Core watches are likely to once again ticking in about a factor of ten more accurate than optical atomic clocks.

“of Course, we are interested in a closer watch,” says Morel from the Metas. “We continue to monitor developments in this area.” Currently, the optical atomic clock as well as the Kernuhr to basic research. “But if the development is promising, we will probably make steps to the development or application of this technology. Because of these chances, we don’t want to miss.”

Created: 23.10.2019, 23:29 PM