Quantum Noise in Balanced Differential Measurements in Optics: Implication to the Wave Modes of Quantum Vacuum

TL;DR

This paper presents a theoretical and experimental analysis challenging the reality of wave modes of quantum vacuum in optical quantum noise, proposing that quantum noise arises from quantum state reduction at detection, with implications for cosmology.

Contribution

It introduces a novel differential detection scheme and provides experimental evidence against the physical reality of quantum vacuum wave modes in optical noise.

Findings

Quantum noise explained by state reduction at detection.

Experimental results support non-reality of vacuum wave modes.

Implications for resolving the cosmological constant problem.

Abstract

Experimental tests for assessing the physical reality of the hypothetical wave modes of quantum vacuum with zero-point energy are of fundamental importance for quantum field theories and cosmology. Physical effects like the Casimir effect have alternate description in terms of retarded interaction between charged matter, due to quantum fluctuations of material dipoles. However, there are simple quantum optical configurations where the hypothetical quantum vacuum modes seem to assume an essential real role in the observable quantum noise of optical signals. I present the logical and theoretical basis of a decisive test that relies on the comparisons of balanced homodyne detection with a novel differential scheme of balanced wave-front division detection, when the two real optical beams at the detectors are derived from one coherent beam as input. Both ideal and practical configurations of my experimental test are discussed. Results from the experiments on balanced detection, beam localization of optical beams, and atomic Bose-Einstein condensates are used to reach definite conclusions against the reality of the wave modes of quantum vacuum. It is shown that the entire quantum noise follows consistently from the state reduction of quantum superpositions of particle-number states at the point of detection, where the quantum measurement is completed. This is consistent with the demonstrated applications of squeezed light in interferometry and quantum metrology. This result achieves consistency between quantum noise in quantum optics and observational cosmology based on general relativity, by avoiding the wave modes of quantum vacuum with divergent zero-point energy density. Generalization from the limited sphere of quantum optics to general quantum field theories promises the complete solution to the problem of a divergent cosmological constant.