Generalized constraints on quantum amplification

TL;DR

This paper generalizes quantum noise constraints for linear amplifiers to include signals with non-c-number commutators, such as fermion currents, extending previous results limited to bosonic fields.

Contribution

It introduces a broader set of quantum constraints on amplification noise, applicable to both bosonic and fermionic signals, enhancing understanding of quantum limits in diverse systems.

Findings

Derived noise constraints for fermionic signals

Extended quantum amplification limits beyond bosonic systems

Provided theoretical framework for non-c-number commutators

Abstract

We derive quantum constraints on the minimal amount of noise added in linear amplification involving input or output signals whose component operators do not necessarily have c-number commutators, as is the case for fermion currents. This is a generalization of constraints derived for the amplification of bosonic fields whose components posses c-number commutators.