Quantum Noise in Conventional Optical Heterodyne Devices

TL;DR

This paper theoretically demonstrates that quantum noise in conventional optical heterodyne devices is similar to that in homodyne devices, challenging previous assumptions and suggesting no fundamental quantum limit exists for heterodyne noise.

Contribution

It reveals that quantum noise in heterodyne devices behaves like that in homodyne devices, contrary to prior beliefs, and shows this is not limited by the uncertainty principle or Caves's theorem.

Findings

Quantum noise in heterodyne devices is similar to homodyne devices.

No fundamental quantum limit constrains heterodyne device noise.

Experimental data supports the theoretical analysis.

Abstract

By invoking the quantum theory of optical coherence, we theoretically show that the quantum noise in conventional optical heterodyne devices, which were previously identified as usual phase-insensitive amplifiers with additional quantum noise, is similar to that in optical homodyne devices, as verified by experimental data. Albeit more study is demanded to understand this result, it is certain that neither the uncertainty principle nor Caves's theorem for quantum noise of linear amplifiers sets a limit to the quantum noise of heterodyne devices.