A Reinterpretation of Antibunching and the Hong–Ou–Mandel Effect Based on Natural Quantum Theory — The True Image of Light’s Continuity and Coherence

Lei Yian

I. Introduction: Is Light Really "Individual Photons"?

In modern quantum optics, there are two experiments regarded as "proving the existence of photons":

Single-photon antibunching;

Hong–Ou–Mandel (HOM) interference (HOM dip).

Their common feature is that the correlation detection signals exhibit non-classical behavior.For example:

g⁽²⁾(0) < 1

is referred to as the hallmark of "non-classical light";in the HOM experiment, when two photons incident on a beam splitter simultaneously, the "coincidence counting being zero" at the output ports is interpreted as "two photons always reflecting or transmitting in pairs."

However, from the perspective of Natural Quantum Theory (NQT),these phenomena do not indicate that "light is discrete particles";on the contrary, they reveal:

Light is a continuous field system with inherent coherence and self-modulation characteristics.

II. Explanations and Dilemmas of Instrumental Quantum Theory

(1) Explanations of the Photon Model

In quantum electrodynamics (QED):

The light field is quantized into Fock states;

The single-photon state |1⟩ is considered a fundamental particle with energy ℏω;

If a source emits "true single photons," its intensity correlation should satisfy:

g⁽²⁾(0) = ⟨a†a†aa⟩ / ⟨a†a⟩² = 0

Experimentally, single-photon sources (such as quantum dots and ion traps) have indeed measured g⁽²⁾(0) < 0.01,which is regarded as direct evidence for photons.

(2) Dilemmas:

Yet this gives rise to several logical problems:

Detector responses are inherently statistical, and signal "intervals" cannot directly reflect the nature of the field;

Fock states cannot propagate in free space, as they lack definite phase and time-domain structures;

The "decoherence" in HOM interference, explained by photon path superposition, introduces paradoxes of non-locality and "virtual identity";

The classical wave model should converge to QED results in the weak-light limit, but QED claims that "g⁽²⁾ < 1 is classically impossible."

In other words, "non-classicality" is merely a mathematical definition relative to the ideal linear Gaussian random field, not a property of physical reality.

III. The Perspective of Natural Quantum Theory: Light Is a Continuous Field, Not Discrete Particles

Within the framework of NQT:

Light is a continuous electromagnetic wave packet, whose energy distribution and coherence characteristics are determined by the physical structure of the source;

The so-called "single-photon source" does not emit discrete particles, but rather ultra-short, spatially localized wave packet pulses in time;

Both "antibunching" and the "HOM effect" are manifestations of the nonlinear time-correlation characteristics of continuous wave packets.

IV. NQT Interpretation of the Antibunching Effect

(1) Physical Process

The radiation of an atom or quantum dot is an energy relaxation process of an excited system.When it emits a wave packet, the system transitions to the ground state and will not emit light again until re-excited.Thus, the detected radiation sequence is temporally anti-correlated.

This means:

g⁽²⁾(0) < 1

is not the "non-classicality" of the light field itself,but the dynamic self-exclusion effect of the emitter.

In other words:

"Antibunching" is a non-stationary behavior of the emitter, not the quantum nature of light.

(2) Continuous Field Calculation

For a random pulse sequence I(t) = ∑ᵢ f(t−tᵢ),if there is exclusion between tᵢ (i.e., no repeated emission within a short time),its second-order correlation function naturally satisfies:

g⁽²⁾(0) < 1

This can be fully derived using classical random processes and field superposition calculations,without introducing the concept of "single-photon states."

V. NQT Interpretation of the Hong–Ou–Mandel Effect

The HOM experiment is the "holy grail" of quantum optics,regarded as demonstrating "two-photon interference."

(1) Key Experimental Points

Two identical single-photon wave packets are incident on a 50:50 beam splitter.If they arrive simultaneously, the "coincidence counting" at the output ports disappears.QED interprets this as "two photons always exit in pairs, either reflected or transmitted."

(2) NQT Reinterpretation

In NQT:

Each "photon" is merely an electromagnetic wave packet with finite duration;

When the two wave packets are perfectly matched in time and phase at the beam splitter,the superimposed field exhibits complete constructive interference on one side and complete destructive interference on the other.

This is exactly the destructive interference of classical waves —only now the wave packets are ultra-short with complex modulation structures, leading to "instantaneous zero coincidence" in the correlation signal.

(3) Continuous Wave Calculation Model

Let the two input fields be:

E₁(t) = E₀ f(t)e^(iωt), E₂(t) = E₀ f(t−τ)e^(i(ωt+ϕ))

The outputs of the beam splitter are:

E_A = (E₁ + E₂)/√2, E_B = (E₁ − E₂)/√2

When τ=0 and ϕ=0, destructive interference occurs at output port B:

I_B = |E_B|² = 0

This directly corresponds to the HOM dip — it can be fully explained by the coherent superposition of waves, without the need for photons.

(4) "Two-Photon Interference" Is a Linguistic Misleading

In the NQT context, there are no "two photons," only two coherent field pulses.The so-called "two-photon interference" is actually the full coherent coupling of two wave packets.If the time or phase is misaligned, the correlation is restored.

This is completely consistent with the physical laws of arbitrary coherent wave superposition.

VI. Why Must QED Claim "Non-Classicality"?

QED’s "non-classicality criterion" originates from mathematics:For any classical random field (with positive-definite intensity distribution),

g⁽²⁾(0) ≥ 1.

If experiments measure g⁽²⁾(0) < 1,it implies that the statistical distribution of the field intensity cannot be represented as a positive-definite probability function.

However, NQT points out:This "non-classicality criterion" is only a constraint on statistical models,not a judgment on physical fields.

Because the electromagnetic field is a deterministic oscillatory system at the microscale,the time correlation of its emission and detection is determined by the dynamic coupling between the source and the detector,and is not constrained by the mathematical requirement of "positive-definite distribution."

VII. The Common Essence of Antibunching and the HOM Effect

Phenomenon	Instrumental Quantum Theory Interpretation	Natural Quantum Theory Interpretation
Single-photon antibunching	Photons cannot exist simultaneously	Temporal exclusion of the emitter
HOM interference	Two-photon path superposition	Coherent superposition of two wave packet fields
g⁽²⁾(0) < 1	Non-classical light field	Non-stationary emission or coherent extinction
Coincidence = 0	Photons are indistinguishable	Destructive interference due to perfect field mode matching

Both phenomena collectively reveal:

The coherence and interference of light do not arise from particle superposition, but from the wave dynamics of the field.

VIII. Conclusion: Reinterpreting the True Meaning of "Quantum Optics"

Antibunching and the HOM effect were once regarded as irrefutable evidence for the photon theory,but NQT shows that:they are actually coherent phenomena of continuous waves,and "photons" are merely discrete energy records of these wave packets during detection.

Light is not discrete particles, but a continuous field.The so-called "single-photon behavior" is just the wave packet dynamics under extreme conditions.

When we reunderstand this,the mysterious veil of quantum optics is lifted —what remains is a clear physical image and a complete causal chain.

Nature is not mysterious; we have merely misinterpreted her frequency spectrum.Antibunching and the HOM effect are not victories of photons, but victories of the continuous field.