1.2.3 The Bloch sphere

Course subject(s) Module 1: Working with Single Qubits

Until now, we have seen qubits only in the braket notation. To get a more visual and geometrical understanding of a single qubit, Arjen will introduce the Bloch Sphere. This three dimensional sphere of radius 1, can also help us understand the action of unitary gates and measurement on a single qubit.

Main Takeaways

  • On the Z axis of the Bloch Sphere the eigenstates of the Z basis are found, this also is followed by the X and Y axis.
  • The Born Rule is the underlying reason why any single qubit can be represented on the Bloch Sphere.
  • Unitary gates operations can be represented as rotations on the Bloch Sphere.
  • A measurement on a certain basis projects the qubit state onto one of its eigenstates.
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