Readout scheme for solid-state nuclear clock

Project Information

CRYSTALCLOCK

Grant agreement ID: 882708

DOI

10.3030/882708

Project closed

EC signature date 25 February 2020

Start date 1 April 2020

End date 31 March 2022

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 186 167,04

EU contribution

€ 186 167,04

Coordinated by

TECHNISCHE UNIVERSITAET WIEN
Austria

Periodic Reporting for period 1 - CRYSTALCLOCK (Readout scheme for solid-state nuclear clock)

Reporting period: 2020-04-01 to 2022-03-31

Summary of the context and overall objectives of the project

Time measurement is a technological and commercial need. And for that, people build clocks. Improvement in time measurement goes hand in hand with technological advancements. That is because the accurately measured time can be related to other measurements, distance, gravitational field, and fundamental constants. The nuclear clock will be the next step in improving the technology for accurate measurements and metrology.

The CRYSTALCLOCK project is developing a readout scheme for the Thorium nuclear clock. The readout scheme is based on nuclear quadrupole resonance spectroscopy, (NQRS). The spectroscopy will decipher the microscopic structure of the Thorium atoms in a host crystal.

While conventional atomic clocks rely on the 3-level interrogation scheme where the clock transition is linked to a fast transition that serves for readout. Thorium nuclear clock provides only two accessible nuclear levels. Integrating Thorium ions into a solid-state ionic crystal introduces additional energy levels that will allow for readout using radiofrequency spectroscopy-nuclear quadrupole resonance.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

We have successfully grown Thorium, Neptunium, and Uranium doped CaF2 crystals. We are developing an SRR-based spectrometer for NQR spectroscopy. The motivation behind the SRR spectrometer is to have a compact device capable of detecting nuclear resonances in quadrupolar nuclei. This will have applications beyond the nuclear clock.

We have not detected the frequency of the NQR transition yet. However, the work is in progress. The COVID pandemic has delayed many tasks. Meanwhile, we have confirmed the project's feasibility by measuring the electric field gradient on Neptunium in Np:CaF2 using Mossbauer spectroscopy. The measured values are consistent with theoretical predictions from density functional theory (DFT) calculations. We expect to see the NQR transition before the end of the year 2022.

The preliminary results of the Thorium Nuclear Clock Project were presented at the international Thorium conference “Thorium Nuclear Clock Project Workshop” in Berlin, on 6th May 2022. During the period of the project, the team also published a review paper in a prestigious journal in order to spread ideas about the nuclear clock. The project has made great progress. The preliminary results are very encouraging and show that a nuclear clock is a viable option for keeping time. The team is continuing to work on the project and is hopeful that the nuclear clock will be ready for use in the near future.


Beeks, K., Sikorsky, T., Schumm, T., Thielking, J., Okhapkin, M. V., & Peik, E. (2021). The thorium-229 low-energy isomer and the nuclear clock. Nature Reviews Physics, 3(4), 238-248.


RAW data for all NQR and related experiments are kept at ZENODO repository: https://zenodo.org/record/3931904#.YqsKd3VBzmE

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

While growing the crystals for the NQR experiment, we have developed a method to heal the fluoride deficiency that is inherently present in synthetic and natural fluoride crystals. Fluoride deficiency is a common problem for vacuum ultraviolet optics. The publication of this fluorination technique is already in preparation.

The SRR spectrometer is a highly versatile and compact spectrometer that can be used for a variety of applications where nuclear quadrupole resonance spectroscopy is used. Some of the potential applications for the SRR spectrometer include landmine detection, drug detection, medicine authentication, and oil drilling. The SRR spectrometer's portability and battery-powered operation make it an ideal tool for use in a variety of settings. We are already in contact with the TU Wien patent office. We will file the patent as soon as the device is fully functional. We are confident that our device will be a valuable addition to the market, and we are committed to protecting our intellectual property.

NQR laboratory

PCB board of the SRR spectrometer

Uranium doped single CaF2 crystal.