State coherent information

Coherent information of a bipartite Quantum state

import Quantum_entropy

def coh_info_of_state [quantum_state ρ] : ℝ := 
quantum_entropy(pTr_1 ρ) - quantum_entropy ρ

theorem coh_info_of_state_eq_neg_cond_quantum_entropy {quantum_state ρ} :
  coh_info_of_state ρ = - cond_quantum_entropy ρ := 
by simp

• “The negative of the Conditional quantum entropy.

• An information quantity in its own right.

• measures quantum correlations, much like the mutual information does in the classical case.

• The State coherent information of an ebit is equal to one.”

References:

• Wilde2011;