A Primary Radiation Standard Based on Quantum Nonlinear Optics

TL;DR

This paper introduces a new primary radiation standard based on quantum nonlinear optics, utilizing vacuum fluctuations as a fundamental reference for radiometry, enabling calibration without external sources.

Contribution

It demonstrates that quantum vacuum fluctuations can serve as a primary standard for radiometric measurements across broad wavelengths.

Findings

Spectrum shape is nearly independent of laboratory parameters in spontaneous regime.

In high-gain regime, spectrum shape depends solely on the number of photons.

Quantum efficiency can be determined without external calibration.

Abstract

The spectrum of vacuum fluctuations of the electromagnetic field is determined solely from first physical principles and can be seen as a fundamental property that qualifies as a primary radiation standard. We demonstrate that the amplitude of these quantum fluctuations triggering nonlinear optical processes can be used as a reference for radiometry. In the spontaneous regime of photon pair generation, the shape of the emitted spectrum is nearly independent of laboratory parameters. In the high-gain regime, where spontaneous emission turns to stimulated emission, the shape of the frequency spectrum is uniquely determined by the number of created photons. Both aspects allow us to determine the quantum efficiency of a spectrometer over a broad range of wavelengths without the need of any external calibrated source or detector.