Visualizing two qubits

Abstract:I propose a simple visualization for pure two-qubit states, constructed from three components: two Bloch balls for the marginal qubits (the mixed states obtained by ignoring the other qubit, respectively) and an entanglement component consisting of a rotoreflection and a contraction. I prove that this picture accurately captures the local and global structure of the relevant state space without gaps or degeneracies: the underlying parametrization is a global diffeomorphism onto the state space. Finally, I use this picture to visualize conditional states, the entanglement degree(s) of freedom, and single qubit rotations.

Quantum Physics (quant-ph); Physics Education (physics.ed-ph)

arXiv:2610.08897 [quant-ph]

(or arXiv:2610.08897v1 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2610.08897 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

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