Data re-uploading for a universal quantum classifier

Understand

A single qubit provides sufficient computational capabilities to construct a universal quantum classifier when assisted with a classical subroutine.

• This fact may be surprising since a single qubit only offers a simple superposition of two states and single-qubit gates only make a rotation in the Bloch sphere.
• The key ingredient to circumvent these limitations is to allow for multiple data re-uploading.
• A quantum circuit can then be organized as a series of data re-uploading and single-qubit processing units.