Noisy Circuits in PennyLane

Noisy Circuits in PennyLane

This PennyLane tutorial introduces how to model and simulate noisy quantum circuits, an essential skill for understanding how algorithms behave on imperfect near-term hardware and for developing error-mitigation strategies. It explains the language of open quantum systems used to describe noise: quantum channels that act on density matrices, including familiar examples such as bit-flip, phase-flip, depolarizing, and amplitude-damping channels. Using PennyLane's mixed-state (density-matrix) simulator, the tutorial shows how to insert these noise channels into a circuit, simulate the resulting non-unitary dynamics, and observe how the measurement statistics degrade compared to the ideal noiseless case. Crucially, because PennyLane is differentiable, it then demonstrates a distinctive capability: differentiating through the noisy simulation to optimize circuit parameters in the presence of noise, or even to fit the parameters of a noise model to match observed data. By treating noise as a first-class, differentiable part of the computation, the tutorial gives a hands-on introduction to realistic device modeling and noise-aware optimization in PennyLane.

Run it

pip install -r requirements.txt
python demo.py

Source and license

Imported from demonstrations_v2/tutorial_noisy_circuits/demo.py in PennyLaneAI/demos at c52c0abeb5122218aa96b38eea848864cce7323f, under the Apache License 2.0. Original authors: Xanadu and the PennyLane community. The upstream LICENSE is included alongside this example.