  We present an approach to the four laws of black hole thermodynamics by
utilizing the thermodynamics of quantum coherence. Firstly, Hawking effect is
attributed to the decoherence of the two-mode squeezed state in a black hole
spacetime. Then use is made of the relative entropy between undecohered and
decohered squeezed states whose monotonicity gives the zeroth and the second
law, while the first law can be obtained either by the vanishing of the first
derivative of relative entropy or by studying the effective thermal model
generated by the modular Hamiltonian. Futhermore, information-theoretic
arguments give a Planck's form of the third law of black hole thermodynamics.
With this approach we can understand the laboratory analogues of black holes
solely by quantum theory, and find a way to detect the thermodynamics of black
holes produced in colliders.
