Refactor cirq - squin emit and lowering (#520)

Closes #497 

I had to cut down support for some cirq features in lowering, but I
don't think they were used heavily. For example, we no longer have
`CZPowGate` with arbitrary exponents or arbitrary controlled operations.

Also, one more significant breaking change is that `func.Invoke`
statements are no longer emitted as `CircuitOperation`, but are added to
the circuit flat-out. I think this matches user expectations and
otherwise would have been really odd given our new approach with stdlib
functions.

Finally, noise still needs to be done, but that is pending #495, which
should be merged first, I think.

**Edit**: Noise is also done now, but I also had to cut support for
`AmplitudeDampingChannel`, since we can't really represent this with the
current statements in the noise dialect (I think). However, I haven't
seen this used anywhere so far, so I'd suggest we wait for someone to
actually require that feature.

Author: david-pl

src/bloqade/cirq_utils/emit/__init__.py

@@ -1,3 +1,3 @@
 # NOTE: just to register methods
-from . import op as op, noise as noise, qubit as qubit
+from . import op as op, noise as noise, qubit as qubit, clifford as clifford
 from .base import emit_circuit as emit_circuit

src/bloqade/cirq_utils/emit/base.py

@@ -43,16 +43,15 @@ def emit_circuit(
 
     ```python
     from bloqade import squin
+    from bloqade.cirq_utils import emit_circuit
 
     @squin.kernel
     def main():
         q = squin.qubit.new(2)
-        h = squin.op.h()
-        squin.qubit.apply(h, q[0])
-        cx = squin.op.cx()
-        squin.qubit.apply(cx, q)
+        squin.h(q[0])
+        squin.cx(q[0], q[1])
 
-    circuit = squin.cirq.emit_circuit(main)
+    circuit = emit_circuit(main)
 
     print(circuit)
     ```
@@ -62,30 +61,25 @@ def main():
 
     ```python
     from bloqade import squin
+    from bloqade.cirq_utils import emit_circuit
     from kirin.dialects import ilist
     from typing import Literal
     import cirq
 
     @squin.kernel
     def entangle(q: ilist.IList[squin.qubit.Qubit, Literal[2]]):
-        h = squin.op.h()
-        squin.qubit.apply(h, q[0])
-        cx = squin.op.cx()
-        squin.qubit.apply(cx, q)
-        return cx
+        squin.h(q[0])
+        squin.cx(q[0], q[1])
 
     @squin.kernel
     def main():
         q = squin.qubit.new(2)
-        cx = entangle(q)
-        q2 = squin.qubit.new(3)
-        squin.qubit.apply(cx, [q[1], q2[2]])
-
+        entangle(q)
 
     # custom list of qubits on grid
     qubits = [cirq.GridQubit(i, i+1) for i in range(5)]
 
-    circuit = squin.cirq.emit_circuit(main, circuit_qubits=qubits)
+    circuit = emit_circuit(main, circuit_qubits=qubits)
     print(circuit)
 
     ```
@@ -115,7 +109,7 @@ def main():
             f"The method from which you're trying to emit a circuit takes {len(mt.args)} as input, but you passed in {len(args)} via the `args` keyword!"
         )
 
-    emitter = EmitCirq(qubits=qubits)
+    emitter = EmitCirq(qubits=circuit_qubits)
 
     return emitter.run(mt, args=args)
 
@@ -137,7 +131,7 @@ class EmitCirq(EmitABC[EmitCirqFrame, cirq.Circuit]):
     dialects: ir.DialectGroup = field(default_factory=_default_kernel)
     void = cirq.Circuit()
     qubits: Sequence[cirq.Qid] | None = None
-    _cached_circuit_operations: dict[int, cirq.CircuitOperation] = field(
+    _cached_invokes: dict[int, cirq.FrozenCircuit] = field(
         init=False, default_factory=dict
     )
 
@@ -184,7 +178,7 @@ def emit_block(self, frame: EmitCirqFrame, block: ir.Block) -> cirq.Circuit:
 
 
 @func.dialect.register(key="emit.cirq")
-class FuncEmit(MethodTable):
+class __FuncEmit(MethodTable):
 
     @impl(func.Function)
     def emit_func(self, emit: EmitCirq, frame: EmitCirqFrame, stmt: func.Function):
@@ -193,12 +187,22 @@ def emit_func(self, emit: EmitCirq, frame: EmitCirqFrame, stmt: func.Function):
 
     @impl(func.Invoke)
     def emit_invoke(self, emit: EmitCirq, frame: EmitCirqFrame, stmt: func.Invoke):
-        stmt_hash = hash((stmt.callee, stmt.inputs))
-        if (
-            cached_circuit_op := emit._cached_circuit_operations.get(stmt_hash)
-        ) is not None:
+        try:
+            stmt_hash = hash(
+                (stmt.callee, tuple(frame.get(input) for input in stmt.inputs))
+            )
+        except (TypeError, interp.InterpreterError):
+            # NOTE: avoid unhashable types and missing keys, just don't cache them
+            stmt_hash = None
+
+        if stmt_hash is not None:
+            cached_circuit = emit._cached_invokes.get(stmt_hash)
+        else:
+            cached_circuit = None
+
+        if cached_circuit is not None:
             # NOTE: cache hit
-            frame.circuit.append(cached_circuit_op)
+            frame.circuit.append(cached_circuit.all_operations())
             return ()
 
         ret = stmt.result
@@ -230,9 +234,8 @@ def emit_invoke(self, emit: EmitCirq, frame: EmitCirqFrame, stmt: func.Invoke):
             if return_stmt is not None:
                 frame.entries[ret] = sub_frame.get(return_stmt.value)
 
-        circuit_op = cirq.CircuitOperation(
-            sub_circuit.freeze(), use_repetition_ids=False
-        )
-        emit._cached_circuit_operations[stmt_hash] = circuit_op
-        frame.circuit.append(circuit_op)
+        if stmt_hash is not None:
+            emit._cached_invokes[stmt_hash] = sub_circuit.freeze()
+
+        frame.circuit.append(sub_circuit.all_operations())
         return ()

src/bloqade/cirq_utils/emit/clifford.py

@@ -0,0 +1,90 @@
+import math
+
+import cirq
+from kirin.interp import MethodTable, impl
+
+from bloqade.squin import clifford
+
+from .base import EmitCirq, EmitCirqFrame
+
+
+@clifford.dialect.register(key="emit.cirq")
+class __EmitCirqCliffordMethods(MethodTable):
+
+    @impl(clifford.stmts.X)
+    @impl(clifford.stmts.Y)
+    @impl(clifford.stmts.Z)
+    @impl(clifford.stmts.H)
+    def hermitian(
+        self, emit: EmitCirq, frame: EmitCirqFrame, stmt: clifford.stmts.SingleQubitGate
+    ):
+        qubits = frame.get(stmt.qubits)
+        cirq_op = getattr(cirq, stmt.name.upper())
+        frame.circuit.append(cirq_op.on_each(qubits))
+        return ()
+
+    @impl(clifford.stmts.S)
+    @impl(clifford.stmts.T)
+    def unitary(
+        self,
+        emit: EmitCirq,
+        frame: EmitCirqFrame,
+        stmt: clifford.stmts.SingleQubitNonHermitianGate,
+    ):
+        qubits = frame.get(stmt.qubits)
+        cirq_op = getattr(cirq, stmt.name.upper())
+        if stmt.adjoint:
+            cirq_op = cirq_op ** (-1)
+
+        frame.circuit.append(cirq_op.on_each(qubits))
+        return ()
+
+    @impl(clifford.stmts.SqrtX)
+    @impl(clifford.stmts.SqrtY)
+    def sqrt(
+        self,
+        emit: EmitCirq,
+        frame: EmitCirqFrame,
+        stmt: clifford.stmts.SqrtX | clifford.stmts.SqrtY,
+    ):
+        qubits = frame.get(stmt.qubits)
+
+        exponent = 0.5
+        if stmt.adjoint:
+            exponent *= -1
+
+        if isinstance(stmt, clifford.stmts.SqrtX):
+            cirq_op = cirq.XPowGate(exponent=exponent)
+        else:
+            cirq_op = cirq.YPowGate(exponent=exponent)
+
+        frame.circuit.append(cirq_op.on_each(qubits))
+        return ()
+
+    @impl(clifford.stmts.CX)
+    @impl(clifford.stmts.CY)
+    @impl(clifford.stmts.CZ)
+    def control(
+        self, emit: EmitCirq, frame: EmitCirqFrame, stmt: clifford.stmts.ControlledGate
+    ):
+        controls = frame.get(stmt.controls)
+        targets = frame.get(stmt.targets)
+        cirq_op = getattr(cirq, stmt.name.upper())
+        cirq_qubits = [(ctrl, target) for ctrl, target in zip(controls, targets)]
+        frame.circuit.append(cirq_op.on_each(cirq_qubits))
+        return ()
+
+    @impl(clifford.stmts.Rx)
+    @impl(clifford.stmts.Ry)
+    @impl(clifford.stmts.Rz)
+    def rot(
+        self, emit: EmitCirq, frame: EmitCirqFrame, stmt: clifford.stmts.RotationGate
+    ):
+        qubits = frame.get(stmt.qubits)
+
+        turns = frame.get(stmt.angle)
+        angle = turns * 2 * math.pi
+        cirq_op = getattr(cirq, stmt.name.title())(rads=angle)
+
+        frame.circuit.append(cirq_op.on_each(qubits))
+        return ()

src/bloqade/cirq_utils/emit/noise.py

@@ -1,36 +1,53 @@
 import cirq
-from kirin.emit import EmitError
 from kirin.interp import MethodTable, impl
 
 from bloqade.squin import noise
 
 from .base import EmitCirq, EmitCirqFrame
-from .runtime import (
-    KronRuntime,
-    BasicOpRuntime,
-    OperatorRuntimeABC,
-    PauliStringRuntime,
-)
 
 
 @noise.dialect.register(key="emit.cirq")
-class EmitCirqNoiseMethods(MethodTable):
+class __EmitCirqNoiseMethods(MethodTable):
+
+    two_qubit_paulis = (
+        "IX",
+        "IY",
+        "IZ",
+        "XI",
+        "XX",
+        "XY",
+        "XZ",
+        "YI",
+        "YX",
+        "YY",
+        "YZ",
+        "ZI",
+        "ZX",
+        "ZY",
+        "ZZ",
+    )
 
     @impl(noise.stmts.Depolarize)
     def depolarize(
         self, interp: EmitCirq, frame: EmitCirqFrame, stmt: noise.stmts.Depolarize
     ):
         p = frame.get(stmt.p)
-        gate = cirq.depolarize(p, n_qubits=1)
-        return (BasicOpRuntime(gate=gate),)
+        qubits = frame.get(stmt.qubits)
+        cirfq_op = cirq.depolarize(p, n_qubits=1).on_each(qubits)
+        frame.circuit.append(cirfq_op)
+        return ()
 
     @impl(noise.stmts.Depolarize2)
     def depolarize2(
         self, interp: EmitCirq, frame: EmitCirqFrame, stmt: noise.stmts.Depolarize2
     ):
         p = frame.get(stmt.p)
-        gate = cirq.depolarize(p, n_qubits=2)
-        return (BasicOpRuntime(gate=gate),)
+        controls = frame.get(stmt.controls)
+        targets = frame.get(stmt.targets)
+        cirq_qubits = [(ctrl, target) for ctrl, target in zip(controls, targets)]
+        cirq_op = cirq.depolarize(p, n_qubits=2).on_each(cirq_qubits)
+        frame.circuit.append(cirq_op)
+        return ()
 
     @impl(noise.stmts.SingleQubitPauliChannel)
     def single_qubit_pauli_channel(
@@ -39,9 +56,15 @@ def single_qubit_pauli_channel(
         frame: EmitCirqFrame,
         stmt: noise.stmts.SingleQubitPauliChannel,
     ):
-        ps = frame.get(stmt.params)
-        gate = cirq.asymmetric_depolarize(*ps)
-        return (BasicOpRuntime(gate=gate),)
+        px = frame.get(stmt.px)
+        py = frame.get(stmt.py)
+        pz = frame.get(stmt.pz)
+        qubits = frame.get(stmt.qubits)
+
+        cirq_op = cirq.asymmetric_depolarize(px, py, pz).on_each(qubits)
+        frame.circuit.append(cirq_op)
+
+        return ()
 
     @impl(noise.stmts.TwoQubitPauliChannel)
     def two_qubit_pauli_channel(
@@ -50,33 +73,18 @@ def two_qubit_pauli_channel(
         frame: EmitCirqFrame,
         stmt: noise.stmts.TwoQubitPauliChannel,
     ):
-        ps = frame.get(stmt.params)
-        paulis = ("I", "X", "Y", "Z")
-        pauli_combinations = [
-            pauli1 + pauli2
-            for pauli1 in paulis
-            for pauli2 in paulis
-            if not (pauli1 == pauli2 == "I")
-        ]
-        error_probabilities = {key: p for (key, p) in zip(pauli_combinations, ps)}
-        gate = cirq.asymmetric_depolarize(error_probabilities=error_probabilities)
-        return (BasicOpRuntime(gate),)
-
-    @staticmethod
-    def _op_to_key(operator: OperatorRuntimeABC) -> str:
-        match operator:
-            case KronRuntime():
-                key_lhs = EmitCirqNoiseMethods._op_to_key(operator.lhs)
-                key_rhs = EmitCirqNoiseMethods._op_to_key(operator.rhs)
-                return key_lhs + key_rhs
+        ps = frame.get(stmt.probabilities)
+        error_probabilities = {
+            key: p for (key, p) in zip(self.two_qubit_paulis, ps) if p != 0
+        }
 
-            case BasicOpRuntime():
-                return str(operator.gate)
+        controls = frame.get(stmt.controls)
+        targets = frame.get(stmt.targets)
+        cirq_qubits = [(ctrl, target) for ctrl, target in zip(controls, targets)]
 
-            case PauliStringRuntime():
-                return operator.string
+        cirq_op = cirq.asymmetric_depolarize(
+            error_probabilities=error_probabilities
+        ).on_each(cirq_qubits)
+        frame.circuit.append(cirq_op)
 
-            case _:
-                raise EmitError(
-                    f"Unexpected operator runtime in StochasticUnitaryChannel of type {type(operator).__name__} encountered!"
-                )
+        return ()

src/bloqade/cirq_utils/emit/qubit.py

@@ -14,11 +14,13 @@ def new(self, emit: EmitCirq, frame: EmitCirqFrame, stmt: qubit.New):
         n_qubits = frame.get(stmt.n_qubits)
 
         if frame.qubits is not None:
-            cirq_qubits = [frame.qubits[i + frame.qubit_index] for i in range(n_qubits)]
+            cirq_qubits = tuple(
+                frame.qubits[i + frame.qubit_index] for i in range(n_qubits)
+            )
         else:
-            cirq_qubits = [
+            cirq_qubits = tuple(
                 cirq.LineQubit(i + frame.qubit_index) for i in range(n_qubits)
-            ]
+            )
 
         frame.qubit_index += n_qubits
         return (cirq_qubits,)