Benchmarking dynamical-structure-factor protocols in programmable neutral-atom geometries

arXiv:2609.07634 · quant-ph · Submitted 2026-09-07 · Read on arXiv

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Introduction to the show: ident: Quantum Radio. Generated commentary on the latest quantum physics and condensed matter papers.

Kai: I'm Kai, and with me are Mira and Lev, guest researcher.

Mira: Today's paper: "Benchmarking dynamical-structure-factor protocols in programmable neutral-atom geometries".

Kai: The gist: This work benchmarks dynamical-structure-factor protocols in programmable neutral-atom geometries to assess their feasibility for measuring excitation spectra in various Ising-like spin systems,

Mira: First, who's behind it and why it matters.

Paper summary: Kai: So to recap this paper, "Benchmarking dynamical-structure-factor protocols in programmable neutral-atom geometries," is basically about seeing if we can measure that dynamical structure factor using these neutral atom quantum processors instead of just relying on traditional techniques.

Mira: That's the core thesis: the paper argues that you can extract information about excitation spectra and how materials respond dynamically by using suitable dynamical protocols in quantum simulators, even though this is traditionally done with things like inelastic neutron scattering in real materials.

Kai: They test this feasibility by using numerical simulations of a neutral-atom QPU to assess if this approach works for a broader class of Ising-like spin systems than what has been tested so far.

Mira: Specifically, they benchmark the protocol on systems beyond the standard one-dimensional transverse-field Ising chain, checking its performance in chains with dimerized interactions and even in the two-dimensional transverse-field Ising model.

Lev: The point is to see if this quantum simulator approach can provide a practical route for measuring these response functions where classical simulations become increasingly demanding.

Kai: They also look at how the protocol holds up when you throw in messy, realistic experimental conditions, like finite simulation times and pulse modulation, positional disorder, and even laser noise.

Mira: The paper concludes that their findings show that neutral-atom quantum simulators can provide a practical route to probing dynamical response functions in those demanding regimes.

Lev: So the big picture here is moving from theory on how it might work to showing it can actually be implemented and tested in a programmable hardware environment.

Kai: This means they're paving the way toward experimental implementation of measuring these types of dynamical response functions, which is a significant step forward for condensed matter physics research.

Mira: It’s about proving that the theoretical methods translate into something tangible on a quantum hardware platform.

Conclusion: Kai: So looking at the paper, "Benchmarking dynamical-structure-factor protocols in programmable neutral-atom geometries," we see a lot of work being done to make these complex measurements accessible on programmable hardware.

Mira: The authors are showing that they can take a measurement observable like the dynamical structure factor and apply it to many different spin systems using this specific protocol within neutral atom setups.

Kai: It’s not just about measuring one thing; it’s about proving the general applicability of these protocols across various Ising-like models, from 1D chains to 2D models <ref:2609.07634#pg1>.

Mira: The implication is that for experimentalists, this suggests that neutral-atom quantum simulators are a viable tool for exploring excitation spectra in systems where classical methods become too slow or too complex to handle.

Kai: It means we can start thinking about how this technology could actually be used to probe real materials in ways that are currently inaccessible through conventional means.

Mira: Ultimately, it suggests that the path toward experimental implementation is becoming clearer because they’ve demonstrated the protocol works across these challenging geometries and under realistic noise conditions.

Lev: From a hardware side, if you're building a system for this, Lev would say that the challenge isn't just having the atoms; it's managing all those control parameters—the timing of the pulses and keeping things stable enough to get those clean measurements.

Kai: Exactly. So we’ve gone from abstract ideas about what *could* be done to a concrete demonstration of what *can* be done with these neutral-atom systems for structure factor measurement.

Dipartimento di Fisica e Astronomia dell’Universita’ di Bologna · INFN Sezione di Bologna · PASQAL SAS

quant-ph

Submitted: 2026-09-07

Updated: 2026-10-09

License: http://creativecommons.org/licenses/by/4.0/

Importance score: 85/100

The gist: The gist: This work benchmarks dynamical-structure-factor protocols in programmable neutral-atom geometries to assess their feasibility for measuring excitation spectra in various Ising-like spin

Key concepts

Dynamical Structure Factor (DSF): The DSF is a key tool in physics that reveals how a quantum material responds to external stimuli by measuring its excitation spectrum. In this context, it tells scientists about the energy levels and modes of vibration or excitation within the spin system being studied.
Neutral-Atom Quantum Processing Unit (QPU): This setup uses arrays of neutral atoms trapped in optical tweezers as a programmable quantum computer. These atoms act as qubits, allowing researchers to simulate complex quantum systems like spin models by controlling their interactions and states through laser pulses.
Transverse Field Ising Model (TFIM): The TFIM is a fundamental model used to describe how spins interact in the presence of an external magnetic field. The study specifically used this model, varying its geometry from simple 1D chains to more complex 2D arrays, to test the measurement protocol.
Out-of-Time Correlators: These are specific measurements performed on the neutral atom platform that help capture how quantum information evolves over time. They are used as a proxy for measuring the retarded Green's function, which is essential for calculating the DSF.

Terminology

Benchmark — 7× in this paper · explained in 2 episodes
Fidelity — 4× in this paper · explained in 2 episodes
Phase Transition — 4× in this paper · explained in 2 episodes
Robustness — 4× in this paper · explained in 5 episodes
Accuracy — 3× in this paper · explained in 1 episode
Benchmarking — 3× in this paper · explained in 4 episodes
Adiabatic Preparation — 1× in this paper · explained in 1 episode
Calibration — 1× in this paper · explained in 7 episodes
Hilbert Space — 1× in this paper · explained in 2 episodes
Quantization — 1× in this paper · explained in 13 episodes

Summary

The gist: This work benchmarks dynamical-structure-factor protocols in programmable neutral-atom geometries to assess their feasibility for measuring excitation spectra in various Ising-like spin systems, showing that neutral-atom quantum simulators can provide a practical route to probing dynamical response functions where classical simulations become increasingly demanding

Model and Setup

The study utilizes numerical emulations of a neutral-atom quantum processing unit (QPU) to investigate transverse field Ising models (TFIM) in 2D programmable optical tweezer arrays The Hamiltonian governing the many-atom dynamics is decomposed into three terms: HˆQPU = HˆTFIM + Hˆl + Hˆdet (1) The target TFIM Hamiltonian is defined as X i<j Jijσˆ z i σˆ z j + hx(t) X i σˆ x i (2) The interaction term Jij = JR6/r6 ij is a short-range Van der Waals interaction between (i, j) atom pairs separated by a distance rij, where J and R are defined as the nearest-neighbor interaction and distance, respectively

Dynamical Structure Factor Protocol

The protocol for measuring the dynamical structure factor (DSF) involves several steps starting from state preparation to many-atom dynamics The first step is preparing the low-energy state from the initial QPU state g... g⟩ via a standard quasi-adiabatic protocol of duration Tprep = 800 ns, which leads to a low-energy state parametrized by the ratio J/hx [36] Subsequently, out-of-time correlators are measured in the neutral atom platform using equaltime correlators in a Raman spectroscopy scheme following protocols introduced Refs. [18, 19] The retarded Green’s function is expressed as Gret z,z(i, j, t) = −i 2⟨σˆ z i(t)σˆ z j(0) − σˆ z j(0)σˆ z i(t)⟩Ψ0⟩ (5) For zero temperature, the DSF is simply S zz(k, ω) = − 1/π ImGret z,z(k, ω) The time evolution T = 3200 ns after the local rotation is performed under a constant QPU Hamiltonian approximately equal to HˆTFIM in Eq. (2), parametrized by J/hx

Results on Different Models

The protocol was benchmarked across several system types, including 1D chains with dimerized interactions and the two-dimensional transverse-field Ising model (2D TFIM) For the 1D TFIM, results showed that the protocol recovers the analytically predicted magnon bands, and richer spectra can be accessed in the presence of 1D dimerized interactions In the SSH-Ising model (dimerized chain), a good matching with the two-band picture predicted analytically was observed For the 2D TFIM, small cluster studies at N = 4 × 4 and 6 × 6 highlighted the numerical hardness of simulating the protocol numerically

Robustness and Noise Analysis

A numerical study of the impact of noise sources on the protocol for the 1D TFIM system was performed to assess robustness The influence of noise is first visible in the real-space magnetization dynamics, where fluctuations and decoherence progressively distort the ideal evolution After transformation to momentum-frequency space, these imperfections manifest as a broadening and increased background noise in the reconstructed magnon band These results indicate that the protocol is resilient to realistic levels of experimental noise and remains capable of extracting the essential properties of the excitation spectrum

Conclusion and Outlook

The work successfully emulated neutral-atom pulse protocols to extract the DSF for transverse field Ising models in different geometries This proposal thus paves the road for the experimental implementation Looking ahead, it would be interesting to extend our results to other spin Hamiltonians, such as XY or Heisenberg models, which can be engineered in neutral-atoms

Appendix Details

The preparation of the low energy initial state is achieved through a pseudo-adiabatic protocol with duration T = 800 ns The approximation ratio and fidelity rapidly approach unity as the preparation time increases The numerical implementation uses the pulser library [34] and its backends based on state-vector (emu-sv) and matrix product states (emu-mps) Noise sources considered include laser noise, register noise, environmental noise, and SPAM noise The analysis of the 2D system showed that the DSF band is insensitive to changes in the bond dimension in the paramagnetic regime but shows a clear dependence closer to a quantum phase transition The analytical dispersion relation for dimerized systems shows that the spectral weight is expected to concentrate around the inner band edges located at ω± = 2hx ± J − J′ which are separated by the SSH gap 2J − J′ (C5) The DSF computed with the protocol is expected to be way less resolved than the ideal one due to decoherence and finite measurement limitations The use of a symmetric Parzen window does not modify the purely imaginary character of the Fourier transform but only affects the finite-time frequency resolution The paper concludes that this scheme is expected to be robust against typical noise levels of current neutral-atom devices

References

[1] R. P. Feynman, Simulating physics with computers, Int. J. Theor. Phys. 21, 467 (1982)

[2] Y. Manin, Computable and non-computable., Sovetskoye Radio, Moscow 128 (1980)

[3] I. Georgescu, S. Ashhab, and F. Nori, Quantum simulation, Rev. Mod. Phys. 86, 153 (2014)

[4] T. I. Andersen, N. Astrakhantsev, A. H. Karamlou, J. Berndtsson, J.

Improvements for AI systems

textbfReal-time Dynamical Response Extraction for Quantum Materials: The improved system can measure excitation spectra using neutral-atom quantum simulators in regimes where classical simulations are increasingly demanding. This enables probing dynamical response functions in systems with richer DSFs, moving beyond the limitations of traditional methods like inelastic neutron scattering when studying complex spin models like the two-dimensional transverse-field Ising model (2D TFIM).
textbfRobust Protocol Benchmarking and Noise Resilience: The system can be engineered to assess protocol reliability under realistic experimental conditions by analyzing finite simulation times, pulse modulation, positional disorder, and laser noise. This robustness allows for the extraction of essential properties even when facing imperfections like Laser noise, which is quantified in Table I.
textbfEnhanced Spectral Resolution in Larger Systems: The improved system can extract more continuous and well-defined excitation bands in 2D systems by utilizing advanced numerical methods, such as Matrix Product State (MPS) emulation with large bond dimensions (e.g., χ = 512 for 6x6 lattices), overcoming the finite-size effects that limit resolution in smaller clusters.
textbfContext-Aware Excitation Characterization: The system can distinguish between bulk and edge excitations in dimerized systems by analyzing site-resolved response of the system, which reveals localized modes whose frequency is determined by a residual field, such as J, leading to a local two-level splitting ωedge ≃ 2p h 2x + J squared.
textbfModel Versatility for Engineered Hamiltonians: The improved system can be extended to study more complex physical phenomena by extending the protocol to other spin Hamiltonians, such as XY or Heisenberg models, which are engineered in neutral-atoms, allowing for the simulation of diverse quantum systems beyond Ising-like models.

Abstract

The dynamical structure factor is a central observable in condensed-matter physics, providing direct insight into the excitation spectrum and dynamical response of quantum materials. While it is traditionally accessed in real materials through inelastic neutron scattering, recent works have shown that analogous information can be extracted in quantum simulators using suitable dynamical protocols. So far, these approaches have been demonstrated mainly in paradigmatic integrable one-dimensional models. In this work, we use numerical emulations of a neutral-atom quantum processing unit to assess the feasibility of measuring the dynamical structure factor in a broader class of Ising-like spin systems. Beyond the standard one-dimensional transverse-field Ising chain, we benchmark the protocol in chains with dimerized interactions and in the two-dimensional transverse-field Ising model, where spectral properties are difficult to access with classical numerical methods at large scales. We further analyze the robustness of the protocol under realistic experimental conditions, including finite simulation times, pulse modulation, positional disorder, and laser noise. Our results show that neutral-atom quantum simulators can provide a practical route to probing dynamical response functions in regimes where classical simulations become increasingly demanding, paving the way toward experimental implementation.