Benchmarking Open-Access Quantum Hardware Through Many-Body Dynamics in the 1D Tilted-Field Ising Model

. Local magnetization, total magnetization, and connected spin correlations were used to track magnetization memory and finite-speed correlation spreading from the central excitation. The ideal simulation shows clear local and total magnetization evolution, as well as connected-correlation spreading outward from

q_8

, giving a baseline for the intended Hamiltonian dynamics. The IBM hardware results reproduce the broad early-time magnetization trend but show compressed local-magnetization values, reduced separation between qubits, and weaker long-range connected-correlation structure. These differences indicate that the open-access quantum hardware preserves some early-time features of the intended dynamics, while longer-time correlation spreading is increasingly obscured by finite sampling, two-qubit gate errors, readout error, decoherence, and circuit depth. Overall, the study uses this spin-chain system as a direct benchmark for testing how much physically meaningful many-body behavior can still be extracted from noisy open-access quantum hardware.

DOI: 10.21203/rs.3.rs-10012803/v1

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q_8

, and evolved using a second-order Trotterized circuit with timestep

\Delta t=0.1

. The reference case,

h_z=0

, was compared with the tilted-field case,

h_z=h_x=0.35625

, across three interaction regimes:

J=0.90h_x

J=h_x

, and

J=1.40h_x

q_8

q_8

, and evolved using a second-order Trotterized circuit with timestep

\Delta t=0.1

. The reference case,

h_z=0

, was compared with the tilted-field case,

h_z=h_x=0.35625

, across three interaction regimes:

J=0.90h_x

J=h_x

, and

J=1.40h_x

q_8

\%

and 87

\%

reduction in two-qubit gate count and circuit depth, respectively. Through such simulations of the real-time dynamics using Trotterized quantum circuits, we exhibit a crossover from thermalizing dynamics of the system at a weak tilt of the field to a strongly localized behavior at large tilt with short evolution times. We also benchmark our obtained results with respect to those from exact simulations.

U(1)

spin conservation and lattice reflection symmetry, and classically diagonalizes the Hamiltonian in the resulting reduced Hilbert space. This design avoids the variational optimization overhead of VQE, the deep coherent circuits required by QPE, and the symmetry-violating subspaces that arise in SKQD. The ground-state energy error is bounded analytically by

\sqrt{8}\,\|H\|\left(1-\sqrt{α_{D_T}}\right)^{1/2}

, where

α_{D_T}

is the probability weight captured by the

D_T

sampled basis states. This bound connects algorithm performance directly to ground-state sparsity and explains the observed accuracy hierarchy across different phases. Benchmarked on the spin-

1/2

Heisenberg XXZ chain (up to

N=62

qubits on the IBM Heron processor), the algorithm achieves a

3.5\%

energy error in the gapped Neel phase (

Δ=2.0

) and below

0.5\%

at the ferromagnetic boundary (

Δ=-1.0

). The accuracy degrades to

28.7\%

in the strongly quasi-long-range-ordered regime (

Δ=0.5

). Spin-spin correlation functions are reproduced across all regimes, confirming that symmetry-filtered real-time sampling provides a practical and noise-resilient pathway to ground-state properties on near-term quantum hardware.