Inconsistent Gate Names

[lazyoracle]

Describe the bug
Naming of gates in C3 is inconsistent with the standard naming convention followed in quantum computing textbooks and community.

Details
What we call X90p (and all similarly named gates for X, Y and Z) is essentially RX(90) as usually referenced elsewhere.

Expected behavior

Current Name	Expected Name
X90p	RX90p
Xp	RXp
X90m	RX90m
Same for Y, Z	Same for Y, Z
CNOT	CRXp
CZ	CRZp
CR	What does this do?
CR90	Seems fine?
iSWAP	Can someone check this?

[fedroy]

I'm not sure that there is really a convention that is agreed upon.
I'm guessing most lab would compile an X in a circuit to be a RX(pi) because ultimately the only difference is a i.
Not sure how you would do it otherwise...

[GlaserN]

I guess this new notation over complicates the notation.
I guess most textbooks would call x90p only to be a X-gate (also qiskit) analogous for being an Y and Z. However It will be useful to seperate between plus and minus gate. And find a unifying notation. However using rx is not really useful as this is mostly used as an pi/2 pulse and not using a notation in degrees, hence not making it more understandable.

For the CZ and CNOT gate I would say the new notation to be very confusing. As text books would only refer to them as such or for CNOT as CX.

[fedroy]

https://qiskit.org/documentation/tutorials/circuits/3_summary_of_quantum_operations.html
This seems relevant.

[lazyoracle]

A renaming and restructuring of how we assign gates and qubits and indices and parameters is due as @nwittler is working on it. That should hopefully adopt OpenQasm specifications which would (ideally) mean we fully comply with Qiskit gate naming scheme. Which in short, is that X, Y, Z refer to Pauli matrix gates and all rotational (and other parametric) gates are specified with a parameter. This also has the added benefit of extra clarity in names reflecting actual gate implementations. If we wish to not take up the Qiskit nomenclature for gates, we would need to discuss, decide and thoroughly document our internal nomenclature that is scalable and flexible. Once that is in place, this discussion of X == RX90p would be moot.

[shaimach]

Whatever scheme we end up with, it should include general parametric gates (more than 2 qubits, more than 1 parameter), as we will certainly have these in the DAQC project.

…

On Fri, 12 Feb 2021, 19:38 Anurag Saha Roy, ***@***.***> wrote: A renaming and restructuring of how we assign gates and qubits and indices and parameters is due as @nwittler <https://github.com/nwittler> is working on it. That should hopefully adopt OpenQasm specifications which would (ideally) mean we fully comply with Qiskit gate naming scheme. Which in short, is that X, Y, Z refer to Pauli matrix gates and all rotational (and other parametric) gates are specified with a parameter. This also has the added benefit of extra clarity in names reflecting actual gate implementations. If we wish to not take up the Qiskit nomenclature for gates, we would need to discuss, decide and thoroughly document our internal nomenclature that is scalable and flexible. Once that is in place, this discussion of X == RX90p would be moot. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#49 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAH3Q4JRWOO7ZMX2OWFRSQDS6VRQBANCNFSM4XK4WZIQ> .

[lazyoracle]

Preview of what gate and qubit naming looks like in OpenQasm and what we hopefully will adopt.

instructions: [
                {"name": "rx", "qubits": [0], "params": [0.4]},
                {"name": "u2", "qubits": [0], "params": [0.4,0.2]},
                {"name": "u3", "qubits": [0], "params": [0.4,0.2,-0.3]},
                {"name": "cx", "qubits": [0,1]},
                {"name": "measure", "qubits": [0], "register": [1], "memory": [0]},
            ]

[lazyoracle]

Related: #57