# Error-Mitigated Quantum Gates Exceeding Physical Fidelities in a Trapped-Ion System

## TL;DR

This paper demonstrates that quantum error mitigation via probabilistic error cancellation in a trapped-ion system can surpass physical gate fidelities, enabling higher effective fidelity without additional qubits.

## Contribution

It provides experimental evidence that error mitigation techniques can exceed the physical fidelity limits in a trapped-ion quantum system.

## Key findings

- Effective gate fidelities surpass physical fidelities.
- Error rates are significantly reduced through error mitigation.
- Demonstrates potential for high-fidelity quantum computations on near-term devices.

## Abstract

Various quantum applications can be reduced to estimating expectation values, which are inevitably deviated by operational and environmental errors. Although errors can be tackled by quantum error correction, the overheads are far from being affordable for near-term technologies. To alleviate the detrimental effects of errors, quantum error mitigation techniques have been proposed, which require no additional qubit resources. Here, we benchmark the performance of a quantum error mitigation technique based on probabilistic error cancellation in a trapped-ion system. Our results clearly show that effective gate fidelities exceed physical fidelities, i.e. we surpass the break-even point of eliminating gate errors, by programming quantum circuits. The error rates are effectively reduced from $(1.10\pm 0.12)\times10^{-3}$ to $(1.44\pm 5.28)\times10^{-5}$ and from $(0.99\pm 0.06)\times10^{-2}$ to $(0.96\pm 0.10)\times10^{-3}$ for single- and two-qubit gates, respectively. Our demonstration opens up the possibility of implementing high-fidelity computations on a near-term noisy quantum device.