  When a one-atom maser is operated in the standard way -- excited, resonant
two-level atoms traverse the resonator at random times -- the emerging atoms
are entangled with the cavity field. As a consequence, the results of
measurements on different atoms tend to be correlated. We show that truly
non-classical correlations can be found between two successive atoms by
studying the properties of the reduced state of such an atom pair. In
particular, we calculate its degree of separability and find parameter ranges
in which it is markedly less than unity.
