How is phase encoding implemented?

PennyLane Help
1

When encoding classical data into quantum data, the commonly used methods are basis encoding, angle encoding, and amplitude encoding. So, is phase encoding also implemented? If so, how is phase encoding implemented?

2

Hi @zj-lucky, I’ve only heard of phase encoding in the context of photonic circuits, and I don’t think it’s comparable to the other encodings you mentioned. As far as I know this isn’t something applicable to the gate-based circuit model, so I would recommend choosing one of the first three methods you mentioned.

3

Thank you, then may I ask if using the RZ gate for angle encoding is equivalent to phase encoding?

4

Hi, @CatalinaAlbornoz Is my understanding above correct?

5

Hi @zj-lucky,

I suppose you could do something like this, however remember that the RZ gate only adds a global phase, which doesn’t affect the outcome probabilities (learn more here in the Codebook). This is probably why it’s not generally used for encoding data.

Global phase becomes important when you do something like Quantum Phase Estimation (QPE). QPE is one of the most important algorithms in quantum computing. You can learn more in this demo or this Codebook module.