# Bounds on skew information and local quantum uncertainty for state conversion

## TL;DR

This paper derives fundamental upper bounds linking local quantum uncertainty and skew information during quantum state conversions, revealing inherent limitations in the process.

## Contribution

It introduces new bounds on LQU and skew information for bipartite states under specific quantum channels, highlighting limitations in state conversion.

## Key findings

- Bound on LQU for bipartite channels with commuting Kraus operators.
- Bound on skew information after quantum steering channels.
- Limits on state conversion related to LQU and skew information.

## Abstract

We establish strict upper bounds on local quantum uncertainty (LQU) and skew information associated with state conversion via certain quantum channels. Specifically, we obtain a bound on the achievable LQU for bipartite channels whose Kraus operators commute with nondegenerate von Neumann measurements on the first subsystem, and this LQU bound is expressed in terms of the skew information for the first subsystem. Furthermore, we establish a bound on the skew information of one subsystem obtained from any initial bipartite state subject to any quantum steering channel, and this bound is expressed in terms of the LQU for the initial joint-system state. Our two claims show that state conversion has fundamental limitations relating LQU with skew information.