Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two-Qubit Bloch Sphere   Three unit spheres were used to represent the two-qubit pure states. The
three spheres are named the base sphere, entanglement sphere, and fiber sphere.
The base sphere and entanglement sphere represent the reduced density matrix of
the base qubit and the non-local entanglement measure, concurrence, while the
fiber sphere represents the fiber qubit via a simple rotation under a local
single-qubit unitary operation; however, in an entangled bipartite state, the
fiber sphere has no information on the reduced density matrix of the fiber
qubit. When the bipartite state becomes separable, the base and fiber spheres
seamlessly become the single-qubit Bloch spheres of each qubit. Since either
qubit can be chosen as the base qubit, two alternative sets of these three
spheres are available, where each set fully represents the bipartite pure
state, and each set has information of the reduced density matrix of its base
qubit. Comparing this model to the two Bloch balls representing the reduced
density matrices of the two qubits, each Bloch ball corresponds to two unit
spheres in our model, namely, the base and entanglement spheres. The
concurrence-coherence complementarity is explicitly shown on the entanglement
sphere via a single angle.

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The categories of this paper are: solv-int
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The categories of this paper are: adap-org
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
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The categories of this paper are: mtrl-th
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The categories of this paper are: chem-ph
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: econ
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The categories of this paper are: math
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The categories of this paper are: q-bio
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph