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arxiv: 2605.08350 · v1 · submitted 2026-05-08 · 🪐 quant-ph · cond-mat.stat-mech· cond-mat.str-el

Recognition: 2 theorem links

· Lean Theorem

Quantum trajectory simulation of two-dimensional non-equilibrium steady states with a trapped ion quantum processor

Anna Dalmasso , Arash Jafarizadeh , Julian Boesl , Jared Jeyaretnam , Sheng-Hsuan Lin , Andrew G. Green , Frank Pollmann , Michael Knap
show 3 more authors
Juan P. Garrahan Henrik Dreyer Adam Gammon-Smith
Authors on Pith no claims yet

Pith reviewed 2026-05-12 00:47 UTC · model grok-4.3

classification 🪐 quant-ph cond-mat.stat-mechcond-mat.str-el
keywords quantum trajectoriesnon-equilibrium steady statestrapped-ion quantum processoropen quantum systemssquare latticepersistent currenthard-core bosonsfermions
0
0 comments X

The pith

A trapped-ion quantum processor implements quantum trajectories for interacting particles on a driven two-dimensional lattice.

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

The paper establishes that quantum trajectory methods can be run on a quantum computer to model a square lattice of hard-core bosons or fermions with stochastic particle injection at one corner and removal at the opposite corner. This driving produces a non-equilibrium steady state carrying a persistent current. The experiment measures how the choice of particle statistics, the presence of interactions, and an applied magnetic field each change the steady-state densities and currents. Because the system is open and two-dimensional, classical simulation becomes intractable for larger sizes, making the quantum approach a direct route to otherwise inaccessible observables.

Core claim

Using mid-circuit measurements and feedback on a trapped-ion quantum processor, quantum trajectories are realized for a two-dimensional system of hard-core bosons or fermions on a square lattice subject to stochastic driving at a source and drain located at opposite corners. The resulting non-equilibrium steady state exhibits a persistent current, with the particle statistics, interactions, and magnetic field each producing measurable changes in the steady-state observables.

What carries the argument

Quantum trajectory simulation via repeated mid-circuit measurements and conditional feedback on the trapped-ion processor, applied to the open 2D lattice with stochastic in-flow and out-flow at opposite corners.

If this is right

  • A persistent current flows across the lattice as a direct consequence of the corner source-drain driving.
  • Bosonic versus fermionic statistics produce distinguishable steady-state density patterns and current magnitudes.
  • Interactions and magnetic fields further modify the current and local occupation numbers in the steady state.
  • The method provides access to open-system observables that grow exponentially costly for classical trajectory sampling.

Where Pith is reading between the lines

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

  • The same trajectory protocol could be applied to larger lattices once hardware error rates permit, reaching regimes where classical Monte Carlo sampling fails.
  • The corner-driven geometry offers a minimal model for studying non-equilibrium transport in two dimensions that could be compared with other driven lattice constructions.
  • Adding tunable long-range interactions or multiple particle species would allow direct tests of whether the observed effects persist or give way to new steady-state phases.

Load-bearing premise

The quantum processor performs the required mid-circuit measurements and feedback operations with error rates low enough that they do not distort the extracted non-equilibrium steady-state densities and currents.

What would settle it

Exact agreement between the measured steady-state particle densities and currents in the non-interacting limit and the corresponding classical or exact small-system predictions, within experimental error bars, would be required; systematic mismatch beyond those bars would falsify the faithful implementation claim.

Figures

Figures reproduced from arXiv: 2605.08350 by Adam Gammon-Smith, Andrew G. Green, Anna Dalmasso, Arash Jafarizadeh, Frank Pollmann, Henrik Dreyer, Jared Jeyaretnam, Juan P. Garrahan, Julian Boesl, Michael Knap, Sheng-Hsuan Lin.

Figure 1
Figure 1. Figure 1: FIG. 1. (a) The setup consists of a 4 [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Average local densities and currents for hard-core [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4. (a) Final snapshots for the local density and instan [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
read the original abstract

Digital quantum computers offer a promising route for studying complex many-body systems that are otherwise inaccessible by their classical counterparts. Capabilities including mid-circuit measurements and feedback allow for simulating the dynamics of interacting open quantum systems. Using the Quantinuum System Model H1 trapped-ion quantum computer, we experimentally realise quantum trajectories for a two-dimensional system of (interacting) particles-hard-core bosons or fermions-undergoing stochastic driving at a source and drain at opposite corners of a square lattice. We study the non-equilibrium steady state with persistent current resulting from the this in/out flow of particles. The particle statistics, presence of interactions, and introduction of a magnetic field produce measurable effects on the steady state. Our findings highlight the rich physics in this corner driven two-dimensional setup and showcases both the power and current limitations of quantum computers as a platform to study it.

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 on the Quantinuum System Model H1 trapped-ion quantum processor of quantum trajectory simulations for a two-dimensional square lattice of hard-core bosons or fermions subject to stochastic particle driving at opposite corners. Mid-circuit measurements and feedback implement the source and drain, yielding a non-equilibrium steady state diagnosed by persistent current and density profiles; the authors state that particle statistics, interactions, and magnetic fields produce measurable effects on these observables.

Significance. If the error analysis and validation hold, the work provides a concrete demonstration that current trapped-ion hardware can simulate open many-body dynamics in two dimensions via quantum trajectories, a regime where classical sampling is already costly. It also surfaces practical limitations of mid-circuit operations, which could guide hardware improvements for non-equilibrium quantum simulation.

major comments (2)
  1. [Methods] Methods section: The implementation of stochastic driving relies on repeated mid-circuit measurements and conditional feedback, yet no quantitative propagation of measurement infidelity (typically ~0.5 %) or feedback latency into systematic biases on the extracted current and densities is supplied. Because the headline claims rest on differences between bosonic/fermionic and interacting/non-interacting runs, even small number-conservation errors can mimic or mask the reported physical signatures.
  2. [Results] Results section: The manuscript presents no direct comparison of the measured steady-state observables against an exact classical ensemble of trajectories for the same small lattice, which is computationally feasible and would serve as an essential benchmark to confirm that hardware errors have not distorted the claimed statistics- and interaction-induced features.
minor comments (1)
  1. [Abstract] Abstract: The phrase 'resulting from the this in/out flow' contains a typographical error and should read 'resulting from this in/out flow'.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive comments and for recognizing the potential of our work in demonstrating quantum trajectory simulations of 2D open many-body systems on current trapped-ion hardware. We address each major comment below and will revise the manuscript to incorporate the suggested improvements.

read point-by-point responses

  1. Referee: [Methods] Methods section: The implementation of stochastic driving relies on repeated mid-circuit measurements and conditional feedback, yet no quantitative propagation of measurement infidelity (typically ~0.5 %) or feedback latency into systematic biases on the extracted current and densities is supplied. Because the headline claims rest on differences between bosonic/fermionic and interacting/non-interacting runs, even small number-conservation errors can mimic or mask the reported physical signatures.

    Authors: We agree that a quantitative error propagation analysis is necessary to rigorously support the observed differences arising from particle statistics and interactions. In the revised manuscript we will add an explicit section that propagates the reported measurement infidelity (~0.5 %) and feedback latency through the quantum trajectory protocol, providing bounds on the resulting systematic biases in the steady-state current and density profiles. We will show that these biases remain smaller than the measured physical contrasts between the bosonic/fermionic and interacting/non-interacting cases, thereby confirming that the reported signatures are not artifacts of number-conservation errors. revision: yes

  2. Referee: [Results] Results section: The manuscript presents no direct comparison of the measured steady-state observables against an exact classical ensemble of trajectories for the same small lattice, which is computationally feasible and would serve as an essential benchmark to confirm that hardware errors have not distorted the claimed statistics- and interaction-induced features.

    Authors: We concur that an exact classical benchmark is both feasible and highly desirable for the small lattices studied. We have performed the corresponding classical ensemble of quantum trajectories and will include a direct side-by-side comparison in the revised Results section. This benchmark will demonstrate quantitative agreement between the hardware data and the classical reference within the experimental uncertainties, thereby validating that the reported effects of statistics, interactions, and magnetic fields are faithfully reproduced and not distorted by hardware imperfections. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental hardware demonstration with no derivation chain

full rationale

The paper is an experimental realization of quantum trajectories on Quantinuum H1 hardware for a 2D driven lattice model. No theoretical derivations, predictions, or first-principles results are claimed that reduce by construction to fitted inputs, self-definitions, or self-citation chains. All central claims rest on direct hardware measurements of steady-state observables, which are externally falsifiable against the physical device and independent of any internal tautology. This matches the default expectation for non-circular experimental work.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The paper is an experimental demonstration that relies on established quantum mechanics and the known capabilities of the trapped-ion platform rather than new theoretical postulates.

axioms (2)
  • standard math Standard quantum mechanics and the Lindblad master equation govern the open-system evolution under stochastic driving.
    Invoked to justify the quantum-trajectory unraveling used in the simulation.
  • domain assumption The Quantinuum H1 processor can execute the required mid-circuit measurements and feedback with fidelity sufficient for steady-state observables.
    Central to the experimental claim but not independently verified in the abstract.

pith-pipeline@v0.9.0 · 5494 in / 1419 out tokens · 56678 ms · 2026-05-12T00:47:34.743412+00:00 · methodology

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Lean theorems connected to this paper

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matches
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extends
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contradicts
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unclear
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Reference graph

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