Probing Interactions between Ultracold Fermions

Abstract

At ultracold temperatures, the Pauli exclusion principle suppresses collisions between identical fermions. This has motivated the development of atomic clocks using fermionic isotopes. However, by probing an optical clock transition with thousands of lattice-confined, ultracold fermionic Sr atoms, we have observed density-dependent collisional frequency shifts. These collision effects have been measured systematically and are supported by a theoretical description attributing them to inhomogeneities in the probe excitation process that render the atoms distinguishable. This work has also yielded insights for zeroing the clock density shift.

accepted to Science

References in corpus (7)

• Sr lattice clock at 1x10^{-16} fractional uncertainty by remote optical evaluation with a Ca clock
• Quantum State Engineering and Precision Metrology using State-Insensitive Light Traps
• Compact, thermal-noise-limited optical cavity for diode laser stabilization at 1 x 10-15
• Nuclear Spin Effects in Optical Lattice Clocks
• The absolute frequency of the 87Sr optical clock transition
• Spectroscopic insensitivity to cold collisions in a two-state mixture of fermions
• Coherent optical phase transfer over a 32-km fiber with 1-s instability at $10^{-17}$

Cited by in corpus (2)

• Bose-Einstein condensation of alkaline earth atoms: ${}^{40}${Ca}
• Decoherence and Collisional Frequency Shifts of Trapped Bosons and Fermions