No-signaling bounds for quantum cloning and metrology

TL;DR

This paper demonstrates how the no-signaling principle constrains and explains the fundamental limits in quantum cloning and metrology, establishing bounds and equivalences rooted in fundamental physics.

Contribution

It derives tight no-signaling bounds for quantum cloning and metrology tasks, linking fundamental physical principles to optimal quantum information processing limits.

Findings

No-signaling bounds match known optimal fidelities and rates.

Heisenberg limit derived from no-signaling principle for specific quantum metrology scenarios.

Equivalence shown between phase-covariant cloning and phase estimation asymptotically.

Abstract

The impossibility of superluminal communication is a fundamental principle of physics. Here we show that this principle underpins the performance of several fundamental tasks in quantum information processing and quantum metrology. In particular, we derive tight no-signaling bounds for probabilistic cloning and super-replication that coincide with the corresponding optimal achievable fidelities and rates known. In the context of quantum metrology, we derive the Heisenberg limit from the no-signaling principle for certain scenarios including reference frame alignment and maximum likelihood state estimation. We elaborate on the equivalence of assymptotic phase-covariant cloning and phase estimation for different figures of merit.