Summary

Quantum technologies is a fast developing scientific and industrial domain with an expected multi-billion Euro market of technological solutions for industries and citizens. It comprises the field of quantum sensing, in which optical lattice clocks (OLCs) are one of the most precise measurement instruments, and quantum computing and simulation, which require the controlled manipulation of quantum objects such as trapped ultra-cold atoms. This project aims at bringing together the fundamental technologies used in these two domains by developing tailored and controllable potentials for lattice clocks, such as high order modes, tweezers, or conveyor belts, potentials able to take advantage of quantum entanglement, and in order to use them to explore and better evaluate the systematic uncertainty of these clocks.

Objectives

The overall objective is to explore the fundamental limits of the accuracy of OLCs by implementing innovating trapping strategy, to exploit the variability in these trapping strategies, to validate the systematic evaluation of OLCs, and to confront systematic evaluation in different European NMIs by clock comparison through optical fibre links.

The specific project objectives are:

1. To study the systematic effects associated with lattice light-shifts and cold collisions by developing tailored dipole trapping potentials for OLC. In addition, to determine how to mitigate lattice-induced de-coherence in shallow lattices, and to mitigate the collision effects that currently limit the use of bosonic isotopes. OLC configurations will include high order transverse Gaussian beams, and patterned or painted potentials. Sub-10^-18 comparisons of lattice light shifts and cold collision shifts (for 10⁴ to 10⁵ atoms) will also be assessed with these configurations.
2. To demonstrate engineered or movable potentials, for dead-time free clocks and active clocks, using novel techniques (e.g. cold atoms in optical tweezers, hollow core fibres, continuous loading of cold atoms, conveyor belt potentials). Then by using this ability, to control and modify the OLC trap geometry, (i) to explore cold collision effects, and (ii) develop methods for the continuous flux of atoms.
3. To demonstrate fast and low-noise readout of hybrid cavity OLCs in environments where strong light-matter interaction is overlapped with the optical lattice. In addition, to study the effects at fractional resolutions of 10^-18 or lower, associated with synthetic interactions and entangled states.
4. To determine the effect of background gas collisions with atoms trapped in dipole traps at fractional resolutions of 10^-18: This will include (i) the measurement of the atom trapping lifetime and frequency shift using clock comparisons, (ii) the controlled insertion of background gas pressure; and (iii) comparison with theoretical models, i.e. from semi-classical approaches to quantum approaches including the anisotropy of collisions.
5. To demonstrate the improved accuracy of OLCs gained from Objectives 1-4 using agile optical fibre link comparisons between European metrology institutes. To facilitate the take up of the technology and measurement infrastructure developed in the project by the measurement supply chain, research organisations (EMN Quantum), standards developing organisations (BIPM Consultative Committee for Time and Frequency (CCTF), EURAMET TC-TF) and end users (time and frequency, fundamental physics and geodesy sectors).