  We propose a method of joint interrogation in a single atom interferometer
which overcomes the dead time between consecutive measurements in standard cold
atomic fountains. The joint operation enables for a faster averaging of the
Dick effect associated with the local oscillator noise in clocks and with
vibration noise in cold atom inertial sensors. Such an operation allows
achieving the lowest stability limit due to atom shot noise. We demonstrate a
multiple joint operation in which up to five clouds of atoms are interrogated
simultaneously in a single setup. The essential feature of multiple joint
operation, demonstrated here for a micro-wave Ramsey interrogation, can be
generalized to go beyond the current stability limit associated with dead times
in present-day cold atom interferometer inertial sensors.
