Welcome to NuQuant – AG von der Wense

Welcome to the homepage of the NuQuant project headed by Lars von der Wense. The goal of the NuQuant project is the development of novel laser technologies for nuclear quantum optics and the quantum optical control of the first nuclear excited state of thorium-229.

Since the development of the laser in 1960, laser spectroscopy of the atomic shell has led to significant technological advances, including, but not limited to, various quantum technologies. In contrast, laser spectroscopy of the atomic nucleus has to this day not been accomplished, although it is expected that the transfer of quantum optics to the field of atomic nuclei will also entail numerous technological and fundamental-physical advances. Expectations include the development of a nuclear optical clock, which could surpass the accuracy of existing optical atomic clocks and has potential applications in metrology, geodesy, satellite-based navigation and data transmission, as well as the development of a nucleus-based qubit for quantum computing and a nuclear-based laser.

Until a few years ago, laser spectroscopy of a nuclear transition seemed to be a technology of the distant future. In recent years, however, science has made considerable progress that now brings laser spectroscopy of the atomic nucleus within reach. These include, in particular, the  direct detection of the first excited nuclear state of thorium-229 in 2016. The first excited nuclear state of thorium-229 plays a special role for the laser spectroscopy of atomic nuclei, as it has the lowest excitation energy of all atomic nuclei, at about 8.3 eV. This energy corresponds to a wavelength of about 150 nm, accessible with modern laser technology. Further milestones in this context are the first measurement of the lifetime and an improved accuracy  of the energy of this excitation state.

Based on these new findings, 'NuQuant' aims to excite the thorium-229 nucleus by laser spectroscopy. For this purpose, a novel cw laser system at a wavelength of 150 nm is to be developed, which will then be used for spectroscopy. After successful excitation, the experiment will be further developed into a nuclear clock based on internal conversion (IC). This will transfer existing quantum technological tools to the atomic nucleus domain to open up the exciting new field of nuclear quantum optics.

Selected literature related to the field:

E. Peik, C. Tamm, Nuclear laser spectroscopy of the 3.5 eV transition in 229Th, Eur. Phys. Lett. 61, 181 (2003).

C.J. Campbell et al., Single-ion nuclear clock for metrology at the 19th decimal place, Phys. Rev. Lett. 108, 120802 (2012).

L. von der Wense et al., Direct detection of the 229Th nuclear clock transition, Nature 533, 47-51 (2016).

B. Seiferle, L. von der Wense, P.G. Thirolf, Lifetime measurement of the 229Th nuclear isomer, Phys. Rev. Lett. 118, 042501 (2017).

J. Thielking et al., Laser spectroscopic characterization of the nuclear-clock isomer 229mTh, Nature 556, 321-325 (2018).

B. Seiferle et al., Energy of the 229Th nuclear clock transition, Nature 573, 243- 246 (2019).

L. von der Wense, B. Seiferle, The 229Th isomer: prospects for a nuclear optical clock, Eur. Phys. J. A 56, 277 (2020).

L. von der Wense, C. Zhang, Concepts for direct frequency-comb spectroscopy of 229mTh and an internal-conversion-based solid-state nuclear clock, Eur. Phys. J. D 74, 146 (2020).

S. Kraemer et al., Observation of the radiative decay of the 229Th nuclear clock isomer, Nature 617, 706-710 (2023).