Quantum noise

Definition:
Quantum noise refers to unwanted disturbances that affect quantum systems and can lead to errors in quantum computations and communications. Unlike classical noise, which typically introduces random errors into a signal, quantum noise can degrade or destroy the quantum properties—such as superposition and entanglement—that are essential for quantum technologies.

Scientific context:
Quantum noise arises from various sources, including thermal fluctuations, electromagnetic interference, imperfect quantum gates, and interactions with the environment. These disturbances cause decoherence, the loss of quantum coherence in qubits, and limit the performance and scalability of quantum computers. Quantum noise is a fundamental obstacle to realizing fault-tolerant quantum systems.

Example in Practice:
Different types of quantum noise affect qubits in specific ways:

• Phase noise alters the relative phase between quantum states.

• Amplitude noise changes the probability distribution of measurement outcomes.

• Depolarizing noise can randomize a qubit’s state completely.

Such noise can cause quantum algorithms to fail or generate incorrect results. To address this, researchers use quantum error correction codes, develop noise-resilient algorithms (like QAOA), and improve qubit isolation and control in experimental setups.

Did you know?
Even minimal quantum noise can render an entire quantum computation useless if not properly managed. That’s why quantum error correction is considered one of the cornerstones for scalable quantum computing.

References

QuEra (n.d.). Noise. https://www.quera.com/glossary/noise