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Probing interactions between ultracold fermions



G K. Campbell, M M. Boyd, J W. Thomsen, M J. Martin, S Blatt, M D. Swallows, Travis L. Nicholson, Tara Fortier, Christopher W. Oates, Scott Diddams, Nathan D. Lemke, Pascal Naidon, Paul S. Julienne, Jun Ye, Andrew Ludlow


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 providing a fundamental understanding of fermionic interactions including the effect of the measurement process. This work has also yielded insights for zeroing the clock density shift.


fermions, optical lattice, strontium, ultracold collisions, atomic clock


Campbell, G. , Boyd, M. , Thomsen, J. , Martin, M. , Blatt, S. , Swallows, M. , Nicholson, T. , Fortier, T. , Oates, C. , Diddams, S. , Lemke, N. , Naidon, P. , Julienne, P. , Ye, J. and Ludlow, A. (2009), Probing interactions between ultracold fermions, Science, [online], (Accessed April 21, 2024)
Created April 16, 2009, Updated October 12, 2021