Relative Entropy and Torsion Coupling

Based on the the geometric realization of entanglement entropy via Ryu-Takayanagi formula, in this work we evaluate the relative entropy for the holographic deformed CFT dual to the torsion gravity coupled to the fermions of nonzero vev in the Einstein-Cartan formulation. We find that the positivity and monotonicity of the relative entropy imposes constraint on the strength of axial-current coupling, fermion mass and equation of state. Our work is the first example to demonstrate the nontrivial constraint on the bulk gravity theory from the quantum information inequalities. Especially, this constraint is beyond the symmetry action principle and should be understood as the unitarity constraint. This talk is based on the work [1] of the authors.