Complete Entropic Inequalities for Quantum Markov Chains

Cheeger inequalities for transient Markov chains

We construct upper and lower bounds for Cheeger-type constants for transient Markov chains. We first treat the situation where there is a detailed balance condition and obtain bounds that rely exclusively on the first and second eigenvalues of the substochastic transition matrix. Secondly, we consider general substochastic transition matrices and develop bounds in this broader setting. The effi...

Some Inequalities for Reversible Markov Chains

Nash Inequalities for Finite Markov Chains

This paper develops bounds on the rate of decay of powers of Markov kernels on finite state spaces. These are combined with eigenvalue estimates to give good bounds on the rate of convergence to stationarity for finite Markov chains whose underlying graph has moderate volume growth. Roughly, for such chains, order (diameter) 2 steps are necessary and suffice to reach stationarity. We consider l...

Approximate quantum Markov chains

This chapter reviews the concept of a Markov chain for random variables and then introduces a generalization to quantummechanical systems. We discuss the subtle differences between classical and quantumMarkov chains and point out difficulties that show up in the quantum case. Unlike the classical case that has been analyzed and understood well in the past, certain aspects of quantumMarkov chain...

Quantum Markov Chains

A new approach to quantum Markov chains is presented. We first define a transition operation matrix (TOM) as a matrix whose entries are completely positive maps whose column sums form a quantum operation. A quantum Markov chain is defined to be a pair (G, E) where G is a directed graph and E = [Eij ] is a TOM whose entry Eij labels the edge from vertex j to vertex i. We think of the vertices of...