  Highly entangled excitations such as Majorana fermions of Kitaev quantum spin
liquids have been proposed to be utilized for future quantum science and
technology, and a deeper understanding of such excitations has been strongly
desired. Here we demonstrate that Majorana fermion's mass and associated
topological quantum phase transitions in the Kitaev quantum spin liquids may be
manipulated by using electric fields in sharp contrast to the common belief
that an insulator is inert under weak electric fields due to charge energy
gaps. Using general symmetry analysis with perturbation and exact
diagonalization, we uncover the universal phase diagrams with electric and
magnetic fields. We also provide distinctive experimental signatures to
identify Kitaev quantum spin liquids with electric fields, especially in
connection with the candidate materials such as $\alpha$-RuCl3.
