Improving an atomic clock on a chip via spin-squeezing

Atom sensors are highly sensitive devices used in time and frequency standards, as well as inertial sensing and precision measurements of electromagnetic fields. Nowadays, they are developed to the extent that they can be limited by their quantum nature, i.e., the standard quantum limit (SQL). This limit arises from the individual and uncorrelated behaviour of the used atoms. However, it has been demonstrated that one can overcome this limit via the generation of quantum correlations and entanglement between the atoms.

Proof of principle entanglement generation can be accomplished via different protocols, but this has very seldom been done in metrology-grade devices. In this thesis, we use a cavity quantum electrodynamics (cQED) platform to create a type of quantum correlated state named spin squeezed. We use as a platform a trapped-atom clock on a chip (TACC) to generate these entangled states.

This metrology-grade device allows us to study the dynamics due to spin interactions in the long time scale, on the order of a second. The stability of the apparatus is confirmed by a fractional frequency Allan deviation of 6×10⁻¹³ at 1 s, a performance beating commercially available compact atom clocks.

quantum metrology, atom chip, entranglement, atomic clock, spin-squeezed states, cavity quantum electrodynamics

Full document (EN) : HAL-04597522