A trimodal resonator for three mutually perpendicular magnetic fields

We describe a trimodal resonator for the simultaneous delivery of three per pendicular magnetic fields. The resonator consists of a shielded loop singl e-mode radio frequency (rf) resonator placed inside of a bimodal waveguide microwave resonator. The microwave modes are nondegenerate, tunable over a range of 100 MHz, and have typical Q factors of 150 and 200. The rf mode is tunable over a range of 125 MHz, and has a typical Q of 45. Control of the relative phase between the three fields is demonstrated. The resonator wil l be used to drive three magnetic dipole transitions coherently between Zee man states in the ground state of Rb-87. (C) 1999 American Institute of Phy sics. [S0034-6748(99)00403-7].