In this Letter, a new fractional entangling transformation(Fr ET) is proposed, which is generated in the entangled state representation by a unitary operator expfiθeabt abTg where aebT is the Bosonic annihilate operator. The operator is actually an entangled one in quantum optics and differs evidently from the separable operator, expfiθeaa t bbTg, of complex fractional Fourier transformation. The additivity property is proved by employing the entangled state representation and quantum mechanical version of the Fr ET. As an application, the Fr ET of a two-mode number state is derived directly by using the quantum version of the Fr ET, which is related to Hermite polynomials.
