Such scattering processes are found to limit the achievable coherence times to less than 12 s (corresponding to a quality factor of 1 x 10(16)), significantly shorter than the predicted 145(40) s lifetime of Sr-87's excited clock state. We investigate the effects of stimulated scattering of optical lattice photons on atomic coherence times in a state-of-the art Sr-87 optical lattice clock. The ability to resolve sub-10(-18)-level frequency shifts in such short timescales will affect a wide range of applications for clocks in quantum sensing and fundamental physics. Synchronous interrogation enables each clock to average at a rate of 3.5 x 10(-17) / root tau, dominated by quantum projection noise, and reach an instability of 6.6 x 10(-19) over an hour-long measurement. Through an anti-synchronous comparison, the fractional instability of both clocks is assessed to be 4.8 x 10(-17) / root tau for an averaging time tau (in seconds). Here we utilize such a local oscillator with two strontium (Sr) optical lattice clocks to achieve an advance in clock stability. A new class of ultrastable lasers based on cryogenic silicon reference cavities has recently demonstrated the longest optical coherence times to date. Advances in laser stabilization have thus enabled rapid progress in clock precision. Optical atomic clocks require local oscillators with exceptional optical coherence owing to the challenge of performing spectros-copy on their ultranarrow-linewidth clock transitions. That deeply affects their interaction properties, and allows a Fermi gas of these atoms to be cooled quickly to the quantum degenerate regime. This, along with the introduction of a new spin polarizing method, enables the operation of a three-dimensional optical lattice clock in the band insulating regime.Ultracold alkaline-earth fermionic atoms with large number of nuclear spin states possess SU(N) symmetry. We also demonstrate record speed for preparing degenerate Fermi seas enabled by the SU(N)-symmetric interactions, reachingT/T-F = 0.22 with 10 nuclear spin states in 0.6 s working with a laser-cooled sample. Accounting for these effects, we demonstrate thermometry accurate to 1% of the Fermi energy. In the deeply degenerate regime, we show through precise measurements of density fluctuations and expansion dynamics that the largeNof spin states under SU(N) symmetry leads to pronounced interaction effects in a system with a nominally negligible interaction parameter. Here, we study an SU(N)-symmetric Fermi liquid of(87)Sr atoms, whereNcan be tuned to be as large as 10. In real materials SU(N) symmetry is an idealization, but this symmetry is pristinely realized in fully controllable ultracold alkaline-earth atomic gases.

Many-body quantum systems can exhibit a striking degree of symmetry unparallelled in their classical counterparts.

John goban