Recent improvements of Bureau National de Me/spl acute/trologie Syste/spl grave/mes de Re/spl acute/fe/spl acute/rence Temps Espace (BNM-SYRTE) fountains FO1 and FO2 are described. Fractional frequency instabilities of 2.9/spl times/10/sup -14//spl tau//sup -1/2/ for FO1 and 1.6/spl times/10/sup -14//spl tau//sup -1/2/ for FO2 have been demonstrated. A preliminary estimate of the systematic frequency shifts gives an uncertainty of /spl plusmn/7.2/spl times/10/sup -16/ for FO1 and /spl plusmn/6.5/spl times/10/sup -16/ for FO2. Furthermore, we present a direct comparison between the two fountains. When a real-time measurement of the collisional shift is included, we observe a stability of the comparison of 5.0/spl times/10/sup -14//spl tau//sup -1/2/ and a frequency difference of /spl delta/=4/spl times/10/sup -16/, well within the combined uncertainties.
['H. Marion', 'F.P. Dos Santos', 'D. Chambon', 'F. Narbonneau', 'M. Abgrall', 'I. Maksimovic', 'L. Cacciapuotti', 'C. Vian', 'J. Grünert', 'P. Rosenbusch', 'S. Bize', 'G. Santarelli', 'Pascale Laurent', 'A. Clairon', 'M.E. Tobar', 'Andre N. Luiten', 'C. Salomon']
BNM-SYRTE fountains: recent results