Stability theorem of depolarizing channels for the minimal output quantum R\'enyi entropies

Abstract

We show that the stability theorem of the depolarizing channel holds for the output quantum $p$-R\'enyi entropy for $p \ge 2$ or $p=1$, which is an extension of the well known case $p=2$. As an application, we present a protocol in which Bob determines whether Alice prepares a pure quantum state close to a product state. In the protocol, Alice transmits to Bob multiple copies of a pure state through a depolarizing channel, and Bob estimates its output quantum $p$-R\'enyi entropy. By using our stability theorem, we show that Bob can determine whether her preparation is appropriate.