Spin clocks: Probing fundamental symmetries in nature.

The detection of the free precession of co-located ³He/¹²⁹Xe nuclear spins (clock comparison) is used as ultra-sensitive probe for non-magnetic spin interactions, since the magnetic dipole interaction (Zeeman-term) drops out in the weighted frequency difference, i.e., Δω = ω_He- γ_He/γ_Xe·ω_Xe of the respective Larmor frequencies. Recent results are reported on searches for (i) short-range P- and T-violating interactions between nucleons, and (ii) Lorentz violating signatures by monitoring the Larmor frequencies as the laboratory reference frame rotates with respect to distant stars (sidereal modulation). Finally, a new experimental initiative to search for an electric dipole moment of ¹²⁹Xe (CP-violation) is discussed, which strongly benefits from the long spin-coherence times obtained, reaching [ABSTRACT FROM AUTHOR]