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arXiv · 2408.03064

Measurement-Based Long-Range Entangling Gates in Constant Depth

Elisa Bäumer·Stefan Woerner
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Abstract

The depth of quantum circuits is a critical factor when running them on state-of-the-art quantum devices due to their limited coherence times. Reducing circuit depth decreases noise in near-term quantum computations and reduces overall computation time, thus, also benefiting fault-tolerant quantum computations. Here, we show how to reduce the depth of quantum sub-routines that typically scale linearly with the number of qubits, such as quantum fan-out and long-range CNOT gates, to a constant depth using mid-circuit measurements and feed-forward operations, while only requiring a 1D line topology. We compare our protocols with existing ones to highlight their advantages. Additionally, we verify the feasibility by implementing the measurement-based quantum fan-out gate and long-range CNOT gate on real quantum hardware, demonstrating significant improvements over their unitary implementations.

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Elisa Bäumer, Stefan Woerner. 2024-08-06. Measurement-Based Long-Range Entangling Gates in Constant Depth. https://doi.org/10.1103/physrevresearch.7.023120

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