Fault-tolerant compiling of classically hard IQP circuits on hypercubes
<|reference_start|>Fault-tolerant compiling of classically hard IQP circuits on hypercubes: Realizing computationally complex quantum circuits in the presence of noise and imperfections is a challenging task. While fault-tolerant quantum computing provides a route to reducing noise, it requires a large overhead for generic algorithms. Here, we develop and analyze a hardware-efficient, fault-tolerant approach to realizing complex sampling circuits. We co-design the circuits with the appropriate quantum error correcting codes for efficient implementation in a reconfigurable neutral atom array architecture, constituting what we call a fault-tolerant compilation of the sampling algorithm. Specifically, we consider a family of $[[2^D , D, 2]]$ quantum error detecting codes whose transversal and permutation gate set can realize arbitrary degree-$D$ instantaneous quantum polynomial (IQP) circuits. Using native operations of the code and the atom array hardware, we compile a fault-tolerant and fast-scrambling family of such IQP circuits in a hypercube geometry, realized recently in the experiments by Bluvstein et al. [Nature 626, 7997 (2024)]. We develop a theory of second-moment properties of degree-$D$ IQP circuits for analyzing hardness and verification of random sampling by mapping to a statistical mechanics model. We provide evidence that sampling from hypercube IQP circuits is classically hard to simulate and analyze the linear cross-entropy benchmark (XEB) in comparison to the average fidelity. To realize a fully scalable approach, we first show that Bell sampling from degree-$4$ IQP circuits is classically intractable and can be efficiently validated. We further devise new families of $[[O(d^D),D,d]]$ color codes of increasing distance $d$, permitting exponential error suppression for transversal IQP sampling. Our results highlight fault-tolerant compiling as a powerful tool in co-designing algorithms with specific error-correcting codes and realistic hardware.<|reference_end|>
@article{hangleiter2024fault-tolerant,
    title={Fault-tolerant compiling of classically hard IQP circuits on hypercubes},
    author={Dominik Hangleiter, Marcin Kalinowski, Dolev Bluvstein, Madelyn Cain,
  Nishad Maskara, Xun Gao, Aleksander Kubica, Mikhail D. Lukin, Michael J.
  Gullans},
    journal={arXiv preprint arXiv:2404.19005},
    year={2024},
    archivePrefix={arXiv},
    eprint={2404.19005},
    primaryClass={quant-ph cond-mat.quant-gas cond-mat.stat-mech cs.CC physics.atom-ph}
}