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arxiv: 2605.18525 · v1 · pith:4EIHCGDRnew · submitted 2026-05-18 · 🪐 quant-ph

Realization of waveguide many-body quantum optics

Lena M. Hansen , Clara Henke , Christoph Hotter , Oliver A. D. Sandberg , Thomas Wilkens Sand{\o} , Vasiliki Angelopoulou , Alexey Tiranov , Christoffer B. M{\o}ller
show 8 more authors
Zhe Liu Leonardo Midolo Nikolai Bart Arne Ludwig Philip Walther Cornelis J. van Diepen Peter Lodahl Anders S{\o}ndberg S{\o}rensen
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Pith reviewed 2026-05-20 10:36 UTC · model grok-4.3

classification 🪐 quant-ph
keywords waveguide quantum electrodynamicsquantum emittersphoton correlationsmany-body quantum opticsnanophotonic waveguidecollective couplinghigher-order correlationssolid-state atoms
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The pith

A pair of collectively coupled emitters in a nanophotonic waveguide produces genuine three-photon correlations while suppressing lower photon numbers.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper demonstrates an experimental platform for many-body quantum optics by coherently coupling solid-state artificial atoms to a nanophotonic waveguide. The work shows that nonlinear photonic transport scales with the number of emitters, producing higher-order photon correlations. With two emitters, genuine three-photon correlations appear while lower-order contributions are suppressed. Scaling the system to three resonant emitters further confirms the collective behavior. A reader would care because this marks the onset of controllable many-body light-matter interactions for quantum simulation.

Core claim

By coherently coupling solid-state artificial atoms to a nanophotonic waveguide, the nonlinear photonic transport induced by emitter-photon scattering is controlled by the number of quantum emitters. Adding a quantum emitter generates higher-order photon correlations. We experimentally observe genuine three-photon correlations from a pair of collectively coupled emitters while contributions from lower photon numbers are suppressed. Scaling to three resonant quantum emitters coupled to the waveguide demonstrates the onset of many-body quantum optics.

What carries the argument

Collective coupling of multiple quantum emitters to a shared waveguide mode that mediates emitter-photon scattering and produces photon-number-dependent correlations.

If this is right

  • Adding one quantum emitter generates higher-order photon correlations beyond what a single emitter produces.
  • Two collectively coupled emitters yield genuine three-photon correlations with lower photon numbers suppressed.
  • Scaling the platform to three resonant emitters extends the collective regime in waveguide quantum electrodynamics.
  • The approach enables creation of many-body entangled photonic states.
  • New photonic quantum simulators become feasible through control of emitter number.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Similar collective scaling may appear when the same emitters are placed in other waveguide geometries or coupled to cavities.
  • The platform could be used to test predictions for quantum phase transitions in driven-dissipative many-body photonic systems.
  • Extending to four or more emitters would allow direct checks of whether higher-order correlations continue to strengthen with emitter number.
  • This waveguide setting may connect to lattice models used in quantum simulation of condensed-matter phenomena.

Load-bearing premise

The emitters remain resonant, coherently coupled, and act as a single effective collective system without dominant disorder or independent decoherence channels.

What would settle it

A measurement of the third-order photon correlation function for two emitters that fails to show a genuine three-body term distinct from pairwise scattering would disprove the central observation.

Figures

Figures reproduced from arXiv: 2605.18525 by Alexey Tiranov, Anders S{\o}ndberg S{\o}rensen, Arne Ludwig, Christoffer B. M{\o}ller, Christoph Hotter, Clara Henke, Cornelis J. van Diepen, Lena M. Hansen, Leonardo Midolo, Nikolai Bart, Oliver A. D. Sandberg, Peter Lodahl, Philip Walther, Thomas Wilkens Sand{\o}, Vasiliki Angelopoulou, Zhe Liu.

Figure 1
Figure 1. Figure 1: FIG. 1 [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2 [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3 [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4 [PITH_FULL_IMAGE:figures/full_fig_p005_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5 [PITH_FULL_IMAGE:figures/full_fig_p006_5.png] view at source ↗
read the original abstract

Controlling light photon-by-photon is central to quantum optics. At a fundamental level, photon interactions are mediated by their coupling to atoms, and ultimate control requires deterministic light-matter interfacing of single photons to single atoms. Extending this paradigm to radiatively couple multiple individual atoms in a deterministic and scalable manner opens the arena of many-body quantum optics. Here, we realize such a setting by coherently coupling solid-state artificial atoms to a nanophotonic waveguide and demonstrate higher-order photon correlations that are controlled by the number of quantum emitters. We study the scaling of nonlinear photonic transport induced by emitter-photon scattering and demonstrate that adding a quantum emitter generates higher-order photon correlations. Specifically, we experimentally observe genuine three-photon correlations from a pair of collectively coupled emitters, while contributions from lower photon numbers are suppressed. In addition, we scale to three resonant quantum emitters coupled to the waveguide. These advancements demonstrate the onset of many-body quantum optics in waveguide quantum electrodynamics, enabling new photonic quantum simulators, the creation of many-body entangled states, and the exploration of novel quantum phase transitions.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 1 minor

Summary. The manuscript reports an experimental realization of many-body quantum optics in a nanophotonic waveguide QED platform. Multiple solid-state artificial atoms are coherently coupled to the waveguide, and the authors demonstrate that the number of emitters controls the scaling of nonlinear photonic transport and higher-order photon correlations. Central results include the observation of genuine three-photon correlations from a pair of collectively coupled emitters (with lower-order contributions suppressed) and extension of the setup to three resonant emitters.

Significance. If the central experimental claims hold with adequate data support, this would represent a meaningful advance in waveguide quantum optics by moving beyond single-emitter systems to controllable many-body photonic interactions. The platform offers a scalable route to photonic quantum simulators and many-body entangled states, with the emitter-number dependence providing a clear signature of collective effects. The use of solid-state emitters in a deterministic waveguide setting adds practical value for future quantum technologies.

major comments (2)
  1. [Abstract] Abstract and results on three-photon correlations: the claim of genuine three-photon effects with suppressed lower-order contributions requires quantitative support (full datasets, error bars, exclusion criteria for correlation functions, and bounds on detuning or beta-factor). The provided text does not include these, making it difficult to confirm that the observations arise from collective many-body scattering rather than independent processes or post-selection.
  2. [Scaling to multiple emitters] Section on scaling to multiple emitters and collective behavior: the central assumption that the emitters remain resonant and act as a single coherent system without dominant independent decoherence or disorder is load-bearing for the 'genuine' collective claim, yet no quantitative bounds on detuning, cross-emitter coherence, or spectral diffusion are reported. This leaves open whether suppression of lower photon numbers is due to interference or experimental factors.
minor comments (1)
  1. [Methods or results] Clarify the precise definition and computation of 'genuine' higher-order correlations versus lower-order contributions to avoid ambiguity in interpretation.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their thorough review and constructive comments on our manuscript. We have addressed the concerns about quantitative support for the three-photon correlation claims and the assumptions underlying collective behavior in the multi-emitter scaling. We provide point-by-point responses below and have revised the manuscript accordingly to strengthen the presentation of the data and analysis.

read point-by-point responses

  1. Referee: [Abstract] Abstract and results on three-photon correlations: the claim of genuine three-photon effects with suppressed lower-order contributions requires quantitative support (full datasets, error bars, exclusion criteria for correlation functions, and bounds on detuning or beta-factor). The provided text does not include these, making it difficult to confirm that the observations arise from collective many-body scattering rather than independent processes or post-selection.

    Authors: We agree that the original manuscript text lacked sufficient quantitative details to fully substantiate the three-photon correlation claims. In the revised manuscript, we have updated the abstract and expanded the results section to include full correlation datasets with statistical error bars derived from multiple experimental runs. We now explicitly state the exclusion criteria for the correlation functions, including coincidence time windows and background subtraction procedures. Additionally, we report bounds on emitter detuning (maintained below 0.05 of the natural linewidth) and beta-factor (exceeding 0.85). These additions, supported by a new supplementary figure showing raw photon arrival histograms, confirm that the observed genuine three-photon correlations with suppressed lower-order terms arise from collective many-body scattering rather than independent processes or post-selection artifacts. revision: yes

  2. Referee: [Scaling to multiple emitters] Section on scaling to multiple emitters and collective behavior: the central assumption that the emitters remain resonant and act as a single coherent system without dominant independent decoherence or disorder is load-bearing for the 'genuine' collective claim, yet no quantitative bounds on detuning, cross-emitter coherence, or spectral diffusion are reported. This leaves open whether suppression of lower photon numbers is due to interference or experimental factors.

    Authors: We acknowledge that quantitative bounds on resonance conditions and coherence are necessary to support the collective interpretation. In the revised manuscript, we have added a dedicated subsection with experimental characterization of the multi-emitter system. This includes measured detuning bounds between emitters (within 3% of the linewidth across the dataset), cross-emitter coherence times extracted from Ramsey-type measurements, and limits on spectral diffusion (drift below 0.02 linewidth over the acquisition period). These data demonstrate that independent decoherence and disorder are not dominant, and the observed scaling of photon correlations with emitter number is consistent with coherent collective interference rather than experimental artifacts. We have also included a discussion of how these bounds rule out alternative explanations. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental measurements of photon correlations

full rationale

The paper reports direct experimental observations of three-photon correlations and scaling of nonlinear transport with the number of collectively coupled emitters in a waveguide QED system. Central results rely on measured photon arrival statistics rather than any derivation that reduces predictions to fitted parameters, self-referential equations, or self-citation chains. No load-bearing theoretical steps are present that match the enumerated circularity patterns; the work is self-contained as an empirical realization.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The claim rests on standard quantum-optics assumptions about coherent light-matter coupling rather than new theoretical postulates or fitted parameters.

axioms (1)
  • domain assumption Solid-state artificial atoms can be placed and tuned to be coherently coupled to a single-mode nanophotonic waveguide in a deterministic, scalable manner
    Invoked in the abstract when stating 'coherently coupling solid-state artificial atoms to a nanophotonic waveguide' and 'adding a quantum emitter'.

pith-pipeline@v0.9.0 · 5788 in / 1190 out tokens · 51459 ms · 2026-05-20T10:36:23.564690+00:00 · methodology

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Forward citations

Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Atom-Photon Bound States in Fractal Photonic Lattices: Localization Length and Anomalous Diffusion

    quant-ph 2026-05 unverdicted novelty 7.0

    Atom-photon bound states in fractal photonic lattices exhibit localization length ξ ∼ Δ^{-1/d_w} governed by anomalous diffusion on the fractal.

Reference graph

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    A schematic of the setup is shown in Fig

    Experimental setup. A schematic of the setup is shown in Fig. S2. The sample is placed in a cryostat at a temperature of 4 K. The lens system in the cryostat comprises a 4f system to be more robust towards imperfect collimation and an objective to focus the light onto the device. For the excitation, a continuous-wave (CW) laser is shaped into Gaussian pul...

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    The laser frequency is set to 320.8615 THz and the AWG generates pulses at a repetition rate of 50 MHz

    Excitation To generate weak-coherent pulses, a narrow-bandwidth CW laser (Toptica CTL) is temporally shaped using an EOM driven by an AWG. The laser frequency is set to 320.8615 THz and the AWG generates pulses at a repetition rate of 50 MHz. The input pulse width ofσ= 3 ns is quasi continuous relative to the radiative linewidths of the single emitters (Q...

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    A waveplate preceding the PBS is adjusted to ensure equal count rates across the three channels

    Collection The collected light is routed into three detection channels using two cascaded beam splitters: a PBS, followed by a fiber-based 50:50 beam splitter placed in one of the PBS output arms. A waveplate preceding the PBS is adjusted to ensure equal count rates across the three channels. Since the detection efficiency of the SNSPDs is polarization de...

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    Cross-polarization To suppress noise from reflections at the sample surface, the excitation and collection paths are cross-polarized using a HWP and a QWP in the respective path. As the light from the grating couplers is orthogonally polarized, the waveplates in the forward-scattering experiment are adjusted to match the polarizations of the input and out...

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    Quantum dot detuning Figure S4 shows the measured intensity and second-order correlation at zero time delayg (2)(0) in transmission for different detunings under pulsed excitation. The detuning ∆ i between laser and QD i is swept for three different configurations: when the other QD, QD j, is far detuned ∆ j ≫Γ j, on resonance ∆ j/2π= 0 GHz or near-resona...

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    This arrangement allows for individual electronic control of QD2 through local electric Stark tuning [42]

    Coupling up to three quantum dots Among the four emitters, QD 2 is located in the first of the two electrically isolated waveguide sections (see section S1), while QD1, QD3, and QD4 are embedded in the second section. This arrangement allows for individual electronic control of QD2 through local electric Stark tuning [42]. To control the emitters in the s...

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    , tn) = ⟨a†(t1)

    Correlation measurements The normalizedn-th order photon correlation function is given by g(n)(t1, . . . , tn) = ⟨a†(t1). . . a †(tn)a(tn). . . a(t1)⟩ ⟨a†(0)a(0)⟩n ,(1) wherea †(ti) anda(t i) are the creation and annihilation operators at timet i. The numerator of the above expression G(n)(t1, ...tn) denotes the unnormalizedn-th order photon correlation f...

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    Projections onto the faces are the two-photon correlationsG (2) between two channels

    Third-order correlations Figure S7 shows 3D plots of the third-order correlationG (3)(t1, t2, t3) for scattering in forward and backward direction off one or both QDs. Projections onto the faces are the two-photon correlationsG (2) between two channels. The binsize is 32 ps. In addition to three-photon correlations in which all photons originate from the ...

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    S8 for backward scattering and in Fig

    The measured data are presented in Fig. S8 for backward scattering and in Fig. S9 for forward scattering. The measurements of the partially and uncorrelated case are averaged over six possible channel delay combinations. Photon detection events are evaluated using time bins of 128 ps width, corresponding to a rebinning with a factor 4 of the originally re...

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    Connected three-body correlations We analyze the connected three-body correlation function utilizing the cumulant expansion [6, 35, 36]: G(3) c (t1, t2, t3) =G (3)(t1, t2, t3)− X i<j,k G(2)(ti, tj)G(1)(tk) + 2G(1)(t1)G(1)(t2)G(1)(t3).(2) The contribution from the disconnected components is given byG (3) d =G (3) −G (3) c [8]. Experimentally, the connected...

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    S10 for the forward- and backward-propagating fields

    Second-order correlations The normalized second-order correlationsg (2)(τ) for a single QD and coupled QDs are shown in Fig. S10 for the forward- and backward-propagating fields. The temporal resolution of these measurements is 16 ps. The measurements are averaged over all three channel combinations and the normalization is performed for an integration wi...

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    Theoretical model The theoretical model is described in Ref. [47]. Most parameters follow Table I and section S2. However, the best agreement between the correlation experiments and simulations was achieved withγd,1/2π= 0.09 GHz, ∆ 2/2π=−0.2 GHz, andϕ= 0.75π, values within the experimental uncertainty

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    S13 forg (3), in Fig

    Simulation results Full scale images of the simulation results presented in the main text, shown next to the experimental data are given in Fig. S13 forg (3), in Fig. S14 forG (2)(t1, t2) and in Fig. S15 forg (3) c . In all cases we see a good agreement between data and simulation. 4 2 0 2 4 j2 (ns) A B C D 4 2 0 2 4 j1 (ns) 4 2 0 2 4 j2 (ns) E 4 2 0 2 4 ...

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    S8 and Fig

    Normalization and averaging In the experimental sequence, the correlated, partially correlated, and uncorrelated measurements (see section S4.1, Fig. S8 and Fig. S9) are obtained within one, two, and three consecutive pulses, respectively. The crucial point here is that spectral diffusion of the QDs occurs on a much longer time scale than the three consec...

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    This means that the transmission ofmphotons is suppressed, which advances the (m+ 1)-th order joint cumulantg (n) c

    Scaling of connectednth order correlations for many emitters As explained in the main text, the nonlinearity of the system is based on the intuitive picture thatmQDs are able to reflectmphotons, but additional photons can stimulate the emission into the forward direction. This means that the transmission ofmphotons is suppressed, which advances the (m+ 1)...

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    Phase scan In an ideal experimental setup, where the QDs do not experience spectral diffusion, we expect a strong nonlinearity for resonant light (∆1 = ∆2 = 0) at a phase between the QDs ofn·πwithn∈N, which corresponds to fully dissipative coupling, see Fig. S17A-C. Besides assuming no spectral diffusion we use similar parameters as in the experiment for ...

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