IBM Heron’s Quantum Simulations of Floquet Magnetism Use Qedma Error Mitigation

An IBM Heron R3 processor is now probing quantum systems beyond the reach of the most powerful classical computers, thanks to a collaboration between IBM, Qedma, RIKEN, and BlueQubit. Researchers used Qedma’s QESEM software, a quantum error suppression and error mitigation solution, to investigate the intermediate-time dynamics of a Floquet quantum magnet, a periodically driven system exhibiting unique quantum properties. “Hardware improvements alone are not enough,” explains Qedma; advanced error mitigation is becoming equally important, extending the range of circuits executed with quantitative accuracy. By combining quantum experiments with classical benchmarking, the team identified a regime where classical methods fail while error-mitigated quantum measurements remain reliable. QESEM Software Mitigates Errors in Quantum Simulations Recent demonstrations of quantum processors exceeding the capabilities of classical simulations depend on both hardware advancements and sophisticated error mitigation techniques.

The team’s success relies heavily on QESEM, Qedma’s quantum error suppression and error mitigation software, designed to transform current quantum processors into dependable tools for scientific inquiry. The investigation focused on intermediate-time dynamics, a particularly challenging area for both quantum and classical approaches. Utilizing QESEM, the researchers employed two distinct protocols, QESEM-Unbiased and QESEM-Extrapolated, to achieve reliable results. QESEM-Unbiased combines precise device characterization with quasi-probabilistic error mitigation, yielding expectation values unbiased by characterization errors and accompanied by rigorous statistical error bars. QESEM-Extrapolated, a lower-overhead alternative, extends the simulation timeframe beyond that of QESEM-Unbiased through a carefully validated heuristic procedure. By pairing extensive quantum experiments with classical benchmarking, the collaboration identified a critical regime where current classical methods, including tensor networks and sparse Pauli paths, struggle to provide controlled predictions.

The team reports that in contrast, the error-mitigated quantum measurements from the IBM Heron processor continued to reliably probe the quantum system’s behavior. The complete quantum experiment required approximately 16.4 QPU hours, alongside classical post-processing, while the most demanding classical simulations consumed approximately 540,000 Fugaku core-hours. This ability to surpass classical limitations is particularly significant given the inherent challenges of simulating Floquet systems, which exhibit unique properties like long-lived prethermal states and time crystals. These systems rapidly generate both state and operator entanglement, quickly overwhelming the capacity of classical computers. The researchers emphasize that quantum experimental data can be reused to evaluate multiple observables without additional experimental runs, a significant advantage over classical simulations requiring repeated computation for each measurement. Floquet Systems as Benchmark for Quantum Advantage The pursuit of quantum advantage, demonstrating a quantum computer’s ability to solve problems intractable for even the most powerful classical machines, requires more than just increasing qubit counts. Recent collaborative work involving IBM, RIKEN, and BlueQubit, leveraging Qedma’s QESEM software, highlights the critical role of error mitigation in unlocking this potential, particularly when studying complex quantum systems. Researchers focused on Floquet quantum magnets, periodically driven systems exhibiting unique non-equilibrium physics, as a stringent test case for both quantum hardware and classical simulation techniques.

The team implemented a Floquet circuit on an IBM Heron R3 processor, measuring the magnetization of quantum spins across systems containing up to 74 qubits. Two QESEM protocols were employed: QESEM-Unbiased, delivering unbiased expectation values with rigorous statistical error bars, and QESEM-Extrapulated, a lower-overhead method extending simulation time. These protocols are commercially available, enabling current processors to function as reliable scientific instruments. To rigorously assess the quantum results, the team benchmarked against two leading classical methods: Tensor Networks (PEPS-BP) and Sparse Pauli Paths (SPP). Both approaches, while advanced, rely on approximations to manage computational demands. The research team explains that the findings revealed a critical regime where classical simulations lost controlled convergence, diverging from both each other and the quantum experimental data. QESEM-Unbiased and QESEM-Extrapolated Protocols for Dynamics Qedma, a company specializing in quantum error mitigation, is demonstrating the power of its QESEM software suite by pushing the boundaries of what’s computationally feasible with current quantum hardware. Recent collaborative work with IBM, RIKEN, and BlueQubit leveraged an IBM Heron R3 processor to explore the complex dynamics of Floquet quantum magnets, a system chosen for its rapid generation of both state and operator entanglement. This entanglement poses a significant challenge for classical simulations, and Qedma’s approach aims to overcome those limitations.

The team employed two distinct QESEM protocols during their experiments: QESEM-Unbiased and QESEM-Extrapolated. Complementing this is QESEM-Extrapolated, a lower-overhead method designed to extend the duration of accessible simulations using a carefully validated heuristic procedure. This combination allows researchers to probe deeper into the quantum system’s behavior than previously possible. The researchers found that both classical methods began to falter as the complexity of the simulation increased, noting that both methods rely on controlled approximations to remain computationally tractable and that increasing accuracy demands exponentially more computational resources. This suggests that, in this specific regime, the quantum processor, supported by QESEM, is capable of providing insights inaccessible to even the most powerful classical computers. The complete quantum experiment consumed approximately 16.4 QPU hours, a figure that highlights the computational intensity of the research. The classical approaches tackle the simulation from different angles. PEPS-BP directly evolves the quantum state, while SPP propagates the measured observable, expanding it into a sum of Pauli operators. However, both rely on approximations; PEPS-BP is limited by tensor-network bond dimension, and SPP by the number of significant Pauli terms retained. Increasing accuracy in either method demands rapidly escalating computational resources. As the team shows, both classical approaches accurately reproduce the early stages of the dynamics, but their convergence deteriorates as entanglement and operator complexity continue to grow. The scale of the classical computations was substantial. Achieving a bond dimension of 700 for PEPS-BP required a significant amount of computational resources. The largest SPP simulation utilized 65,536 Fugaku cores for eight hours, amounting to approximately 540,000 Fugaku core-hours, to 4 QPU hours and classical post-processing. This comparison highlights the potential for quantum computers to offer a computational advantage for certain problems, even with current hardware limitations.

The team emphasizes that data from a single quantum experiment can be used to evaluate multiple observables, a task requiring repeated classical simulations. The expectation that quantum computers will eclipse classical capabilities isn’t simply about scaling up qubit counts; demonstrating a genuine advantage requires probing regimes inaccessible to even the most powerful supercomputers, while maintaining trustworthy results. This wasn’t merely a test of hardware, but a validation of a combined hardware and software approach to reliable quantum computation. Central to this success was Qedma’s QESEM software, specifically the QESEM-Unbiased and QESEM-Extrapolated protocols. QESEM-Unbiased, the team explains, “combines high-accuracy device characterization with quasi-probabilistic error mitigation to produce expectation values that are unbiased up to characterization errors,” while QESEM-Extrapolated extends the simulation timeframe. Researchers found that while both methods accurately modeled the initial stages of the quantum system’s evolution, their performance deteriorated as entanglement and operator complexity increased. In stark contrast, “the complete quantum experiment consumed approximately 16.4 QPU hours, in addition to classical post-processing.” This disparity highlights a crucial point: the quantum experiment, leveraging error mitigation, continued to yield reliable data where classical simulations faltered. Source: https://www.qedma.com/how-error-mitigated-quantum-computers-are-reaching-beyond-state-of-the-art-classical-simulation/ Stay currentSee today’s quantum computing news on Quantum Zeitgeist for the latest breakthroughs in qubits, hardware, algorithms, and industry deals. Tags: