Support multi moment gauge compiling

[babacry]

Support multi moment gauge transformation, where target moments will be gauged with new moments, e.g.,

        q₀: ... ───LG0───╭───────────╮────RG0───...
                         │           │
        q₁: ... ───LG1───┤  moments  ├────RG1───...
                         │   to be   │
        q₂: ... ───LG2───┤ gauged on ├────RG2───...
                         │           │
        q₃: ... ───LG3───╰───────────╯────RG3───...

• A common MultiMomentGaugeTransformer class is defined.
• Implemented the CPhase multi moment gauge CPhaseGaugeTransformerMM.
• A moment is a target moment if it contains at least one target op (CZPowGate) and all its operations are supported by this transformer.
• A couple of single qubit gates are supported for CPhaseGaugeTransformerMM, e.g., Pauli Gates, ZPowGate etc. If these gates are detected, gauge will be calculated accordingly. Users can tweak their desired gates by instantiate their own transformer by transformer = CPhaseGaugeTransformerMM(supported_gates=ops.Gateset(g1,g2,g3)). By default _SUPPORTED_GATESET are used.

Example:

  Input:
                  ┌──┐
    0: ───@────────@─────H───Rz(-0.255π)───────────@───────@───────
          │        │                               │       │
    1: ───@^0.2────┼@──────────────────────────────@^0.1───@───────
                   ││
    2: ───@────────@┼────────@─────────────@───────@───────@───────
          │         │        │             │       │       │
    3: ───@─────────@────────@^0.2─────────@^0.2───@───────@^0.2───
                  └──┘
    Output:
                       ┌──┐
    0: ───Y───@─────────@─────PhXZ(a=0,x=1,z=0)───H───X───Rz(0.255π)────────────@───────@────────PhXZ(a=0,x=1,z=1.1)───
              │         │                                                       │       │
    1: ───I───@^-0.2────┼@────Z^0.2───────────────────Y─────────────────────────@^0.1───@────────PhXZ(a=0,x=1,z=0.1)───
                        ││
    2: ───X───@─────────@┼────PhXZ(a=0,x=1,z=1)───────X───@────────────@────────@───────@────────PhXZ(a=0,x=1,z=0)─────
              │          │                                │            │        │       │
    3: ───Z───@──────────@────I───────────────────────I───@^-0.2───────@^-0.2───@───────@^-0.2───Z^-0.4────────────────
                       └──┘

Usage

case 1: default setup, any moment with CZPowGate and optionally with _SUPPORTED_GATES will be gauged (see example above),

cphase_transformer = CPhaseGaugeTransformerMM()
output_circuit = cphase_transformer(input_circuit)

case 2: Only CZPowGate-only moments will be gauged (see test_gauge_on_czpow_only_moments test case),

cphase_transformer = CPhaseGaugeTransformerMM(supported_gates=cirq.Gateset())
output_circuit = cphase_transformer(input_circuit)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

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[babacry]

Hey @eliottrosenberg @NoureldinYosri , here is multi moment gauge compiling!! After evaluating multiple strategies, this approach proves to be optimal regarding both execution speed and future extensibility.

Note gauges could be automatically added to circuits with default setup, wonder if the default setup is suitable for most use cases? (see Example section and Usage section in the description above)

[eliottrosenberg]

LGTM! Great work, @babacry!

[NoureldinYosri]

@babacry is there a way to reuse code you wrote before in _PauliAndZPow ?

[NoureldinYosri]

why is this needed?

[NoureldinYosri]

there are two issues here, default values get initialized once so all instances of the class the don't explicitly pass a rng object will share the same rng. and an rng as a class property means that the class has an internal mutable state which is undesirable.

please prefer to pass the an rng_or_seed to the functions that need it instead of having an internal state

[NoureldinYosri]

didn't you implement the logic for pulling gates somewhere else? or is this specific to these gates?

[NoureldinYosri]

lets make both MultiMomentGaugeTransformer and CPhaseGaugeTransformerMM be @attrs.frozen

then here we can do

    supported_gates = attrs.field(default=_SUPPORTED_GATESET)
    target = attrs.field(default=_TARGET_GATESET, init=False, repr=False, eq=False, hash=False)