12 October 2017
The ANR project CaOC (Cavities for optical clocks) aims at combining ultra-stable laser sources with cavity-assisted non-destructive detection methods to improve the frequency stability of optical lattice clocks. It is part of the Sr clocks project
This project ANR-16-CE30-0003 is funded by ANR since Jan. 2017 for 36 months, and realized at SYRTE, Observatoire de Paris
Objectives
Several noise sources currently limit the frequency stability of optical lattice clocks
- The Dick effect, an aliasing effect between the clock cycle and the frequency noise of the clock laser, is the current limitation to the stability of optical lattice clocks
- The Quantum Projection Noise (QPN) is a fundamental limit for the stability of quantum sensors. For an optical lattice clock probing 104 independent atoms, this limit is around 10-17 at 1 second.
This project aims at overcoming these limits by combining several innovative systems implemented on two optical lattice clocks with strontium atoms:
- a new long ultra-stable optical cavity, used as the clocks’ local oscillator. With a frequency noise lower than the sources currently used, this laser will enable us to reduce the Dick effect, thus closing the gap to the QPN.
- a cavity assisted non-destructive detection of the clocks’ transition probability. The "classical" non-destructivity (the atoms are kept trapped after the detection) will be used to further reduce the Dick effect by reducing the dead time in the clock cycle allowed by the atom recycling. The "quantum" non-destructivity (successive probings of the transition probability exhibit sub-QPN correlations) will be used to show that the QPN can be overcome in optical lattice clocks
Results
A non-destructive detecion has been demonstrated on one of the two Sr clocks available at SYRTE. They rely on the bi-chromatic cavity for trapping and detecting the atoms with an heterodyne system.
It features the following characteristics:
- High signal-to-noise ratio, due to the large finesse of the cavity (16000).
- Insensitivity to technical noise sources (fluctuations of the cavity length, or of the probing laser frequency), thanks to a differential measurement of the atom-induced phase shift in the cavity.
- Homogeneous atom-cavity coupling by simultaneously coupling two adjacent modes of the cavity.
- Detection noise of 4 atoms for a detection in the classical regime.
- Detection noise of 23 atoms for a detection in the quantum regime.
Publications
- A noise-immune cavity-assisted non-destructive detection for an optical lattice clock in the quantum regime
New J. Phys. 19 083002 (2017)
G. Vallet, E. Bookjans, S. Bilicki, U. Eismann, R. Le Targat, J. Lodewyck. - Oral presentation at the BIPM workshop: The Quantum Revolution in Metrology (Sèvres, septembre 2017)
Non-destructive detection for strontium optical lattice clocks : towards a lattice clock in the quantum regime,
G. Vallet, S. Bilicki, E. Bookjans, R. Le Targat, and J. Lodewyck. - poster at Joint European Frequency and Time Forum (EFTF) and International Frequency Control Symposium (IFCS) (Besançon, juillet 2017)
Cavity assisted non-destructive detection for Sr optical lattice clocks,
J. Lodewyck et al.
Job offers
- Post-doc
- Master internship/PhD thesis
Contact
Jérôme Lodewyck
Email: jerome.lodewyck (at) obspm.fr
Tel.: +33 (0) 1 40 51 22 24