It is shown that the Λ quantum beat system, into which a new atomic coherence is introduced, can produce bright two-mode sub-Poissonian light. The Mandel Q parameter is calculated using Scully-Lamb theory. On one hand, when quantum noises of the relative amplitude and relative phase drop to vaccum noise levels, the average mode exhibits sub-Poissonian photon distribution; when quantum noises of the average amplitude and average phase drop to vaccum noise levels, the relative mode exhibits sub-Poissonian photon statistics; the optimum Mandel Q parameter is -0.5. On the other hand, in the above two cases, each of the correlated spontaneous emission laser modes exhibits sub-Poissonian photon statistics with optimum Mandel Q parameter of -0.25.