Single-Qubit Quantum Gates on a Bloch Sphere

Using the Bloch sphere, a cubit can be represented as a unit vector (shown in red) from the origin to the point on the unit sphere with spherical coordinates . A single-qubit quantum gate operating on produces a rotated qubit , represented by the green vector. Check the box for "add gate 2?" to perform a second operation using gate . This produces another qubit , which is represented by the blue vector. You can choose from the gates H, X, Y, Z, S and T as defined in the Details.


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The action of the single-qubit quantum gates can be represented by unitary matrices acting on the qubit
Hadamard gate: ,
Pauli X gate: ,
Pauli Y gate: ,
Pauli Z gate: ,
phase (or gate: ,
gate: .
In general, the operation gives a qubit of the form
with an overall phase factor of no physical significance. Multiplication by removes this factor and reduces the qubit to the canonical form
[1] M. A. Nielsen and I. L. Chuang, Quantum Computation and Quantum Information: 10th Anniversary Edition, Cambridge: Cambridge University Press, 2010.
[2] G. Fano and S. M. Blinder, Twenty-First Century Quantum Mechanics: Hilbert Space to Quantum Computers, Berlin: Springer, 2017.
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