Bloch sphere

The Bloch sphere is a geometrical representation used in quantum computing to visualize the state of a single qubit. It maps the complex probabilities of a qubit onto a three-dimensional unit sphere, making abstract quantum states easier to understand.

On the Bloch sphere, the north and south poles represent the classical bit values of 0 and 1, also known as the computational basis states. Any other point on the surface of the sphere represents a quantum superposition of those two states.

No, the Bloch sphere is strictly limited to visualizing the state of a single, isolated qubit. Entangled multi-qubit systems require complex mathematical spaces and cannot be accurately depicted using a single Bloch sphere.

The representation is named after the Swiss physicist Felix Bloch, who made foundational contributions to the understanding of quantum mechanics and nuclear magnetic resonance. It serves as a fundamental educational tool in modern quantum information science.