The quantum analog of a bit is a qubit, and can be envisaged physically in a number of ways: by the direction of photon polarisation (horizontal or vertical), by nuclear spin (a special 2-valued quantum observable), or by the energy level of an atom (ground or excited). The two so-called basis states of a qubit, analogous to the 0 and 1 of an ordinary bit, are denoted by |0> and |1> respectively.
What we don't have in a quantum system is the simple deterministic notion of the qubit being in one basis state or another. Rather, its notion of being or not being is indeterminate: all we can say about the status of a qubit is that it is in both of the states simultaneously, each with a certain 'probability'.
(Should we call this 'To qubee or not qubee'?