Quantum Error Mitigation: A Review

Due to the interaction with the environment and imperfections of controls, quantum devices are accompanied with errors, whose accumulation could lead to a meaningless computing result. The realization of a full-fledged quantum computer relies on quantum error correction, which however, introduces a huge overhead that makes it challenging for near-term quantum devices. In the noisy intermediate-scale quantum era, quantum error mitigation methods instead of quantum error correction are introduced for suppressing errors. Using a mild cost under reasonable assumptions, quantum error mitigation could enhance the result to achieve a desired computational accuracy, and its feasibility has been demonstrated extensively in theories and experiments. This article aims to introduce and summarize the latest developments in quantum error mitigation, and to comment on potential future directions.