Strong Kantorovich duality for quantum optimal transport with generic cost and optimal couplings on quantum bits

TL;DR

This paper establishes Kantorovich duality for a quantum optimal transport problem involving quantum channels, providing explicit solutions for quantum bits and proving the triangle inequality for quantum Wasserstein divergences.

Contribution

It extends Kantorovich duality to a non-quadratic quantum transport setting with quantum channels, specifically for quantum bits and certain cost operators.

Findings

Derived optimal solutions for primal and dual problems in quantum bits

Proved the triangle inequality for quantum Wasserstein divergences

Established Kantorovich duality for a non-quadratic quantum transport problem

Abstract

We prove Kantorovich duality for a linearized version of a recently proposed non-quadratic quantum optimal transport problem, where quantum channels realize the transport. As an application, we determine optimal solutions of both the primal and the dual problem using this duality in the case of quantum bits and distinguished cost operators, with certain restrictions on the states involved. Finally, keeping the same restrictions regarding the states involved, we use this information on optimal solutions to give an analytical proof of the triangle inequality even for the square of the induced quantum Wasserstein divergences.