BarrierOp and Circuit._add_conditional_barrier (#988)

* Add new `BarrierOp`

Remove `OpType::Barrier` from `MetaOp`

* Add Circuit::add_conditional_gate

unsigned and UnitID constructors

* Add tests to confirm DAG is wired suitably for conditional barrier gates

* Add tests and case handling for conditional barrier over different circumstances

* add `_add_conditonal_barrier` method to Circuit class

* bump

* black format

* Update test_Circ.cpp

* Update add_op.cpp

* bump

* Update add_op.cpp

* Expose BarrierOp to python

* Make `barr` signature accurately reflect internal UnitID, add test

* reformat tests

* Update main.cpp

* Update qasm.py

* Update circuit.pyi

* Update test_Circ.cpp

* requested changes from review

* fix types

* Update basic_circ_manip.cpp

* Update basic_circ_manip.cpp

* Update qasm_test.py

* Update qasm_test.py

* Update circuit.pyi

* Add symbolic substituion test for barrier op

* Update  serialization/deserialization for MetaOp/BarrierOp

* add MetaOp::is_equal

* Add back data type

* Update add_op.cpp

* bump

* bump

* bump

* update with requested changes

pytket/binders/circuit/Circuit/add_op.cpp

@@ -173,6 +173,28 @@ void init_circuit_add_op(py::class_<Circuit, std::shared_ptr<Circuit>> &c) {
           "\n\n:param data: additional data stored in the barrier"
           "\n:return: the new :py:class:`Circuit`",
           py::arg("qubits"), py::arg("bits") = no_bits, py::arg("data") = "")
+      .def(
+          "add_conditional_barrier",
+          [](Circuit *circ, const std::vector<unsigned> &barrier_qubits,
+             const std::vector<unsigned> &barrier_bits,
+             const std::vector<unsigned> &condition_bits, unsigned value,
+             const std::string &_data) {
+            circ->add_conditional_barrier(
+                barrier_qubits, barrier_bits, condition_bits, value, _data);
+            return circ;
+          },
+          "Append a Conditional Barrier on the given barrier qubits and "
+          "barrier bits, conditioned on the given condition bits."
+          "\n\n:param barrier_qubits: Qubit in Barrier operation."
+          "\n:param barrier_bits: Bit in Barrier operation."
+          "\n:param condition_bits: Bit covering classical control condition "
+          "of barrier operation."
+          "\n:param value: Value that classical condition must have to "
+          "hold (little-endian)."
+          "\n:param data: Additional data stored in Barrier operation."
+          "\n:return: the new :py:class:`Circuit`",
+          py::arg("barrier_qubits"), py::arg("barrier_bits"),
+          py::arg("condition_bits"), py::arg("value"), py::arg("data") = "")
       .def(
           "add_circbox",
           [](Circuit *circ, const CircBox &box,
@@ -415,6 +437,26 @@ void init_circuit_add_op(py::class_<Circuit, std::shared_ptr<Circuit>> &c) {
           "\n\n:param data: additional data stored in the barrier"
           "\n:return: the new :py:class:`Circuit`",
           py::arg("units"), py::arg("data") = "")
+      .def(
+          "add_conditional_barrier",
+          [](Circuit *circ, const unit_vector_t &barrier_args,
+             const bit_vector_t &condition_bits, unsigned value,
+             const std::string &_data) {
+            circ->add_conditional_barrier(
+                barrier_args, condition_bits, value, _data);
+            return circ;
+          },
+          "Append a Conditional Barrier on the given barrier qubits and "
+          "barrier bits, conditioned on the given condition bits."
+          "\n\n:param barrier_args: Qubit and Bit in Barrier operation."
+          "\n:param condition_bits: Bit covering classical control "
+          " condition of barrier operation."
+          "\n:param value: Value that classical condition must have to "
+          "hold (little-endian)."
+          "\n:param data: Additional data stored in Barrier operation."
+          "\n:return: the new :py:class:`Circuit`",
+          py::arg("barrier_args"), py::arg("condition_bits"), py::arg("value"),
+          py::arg("data") = "")
       .def(
           "add_circbox",
           [](Circuit *circ, const CircBox &box, const unit_vector_t &args,

pytket/binders/circuit/main.cpp

@@ -27,6 +27,7 @@
 #include "tket/Gate/Gate.hpp"
 #include "tket/Gate/OpPtrFunctions.hpp"
 #include "tket/Gate/SymTable.hpp"
+#include "tket/Ops/BarrierOp.hpp"
 #include "tket/Ops/MetaOp.hpp"
 #include "tket/Ops/Op.hpp"
 #include "tket/Utils/Constants.hpp"
@@ -615,7 +616,7 @@ PYBIND11_MODULE(circuit, m) {
           ":return: set of symbolic parameters for the command");
 
   py::class_<MetaOp, std::shared_ptr<MetaOp>, Op>(
-      m, "MetaOp", "Meta operation, for example used as barrier")
+      m, "MetaOp", "Meta operation, such as input or output vertices.")
       .def(
           py::init<OpType, op_signature_t, const std::string &>(),
           "Construct MetaOp with optype, signature and additional data string"
@@ -625,6 +626,17 @@ PYBIND11_MODULE(circuit, m) {
           py::arg("type"), py::arg("signature"), py::arg("data"))
       .def_property_readonly("data", &MetaOp::get_data, "Get data from MetaOp");
 
+  py::class_<BarrierOp, std::shared_ptr<BarrierOp>, Op>(
+      m, "BarrierOp", "Barrier operations.")
+      .def(
+          py::init<op_signature_t, const std::string &>(),
+          "Construct BarrierOp with signature and additional data string"
+          "\n:param signature: signature for the op"
+          "\n:param data: additional string stored in the op",
+          py::arg("signature"), py::arg("data"))
+      .def_property_readonly(
+          "data", &BarrierOp::get_data, "Get data from BarrierOp");
+
   auto pyCircuit = py::class_<Circuit, std::shared_ptr<Circuit>>(
       m, "Circuit", py::dynamic_attr(),
       "Encapsulates a quantum circuit using a DAG representation.\n\n>>> "

pytket/binders/include/add_gate.hpp

@@ -27,9 +27,12 @@ static Circuit *add_gate_method(
     Circuit *circ, const Op_ptr &op, const std::vector<ID> &args,
     const py::kwargs &kwargs) {
   if (op->get_desc().is_meta()) {
+    throw CircuitInvalidity("Cannot add metaop to a circuit.");
+  }
+  if (op->get_desc().is_barrier()) {
     throw CircuitInvalidity(
-        "Cannot add metaop. Please use `add_barrier` to add a "
-        "barrier.");
+        "Please use `add_barrier` to add a "
+        "barrier to a circuit.");
   }
   static const std::set<std::string> allowed_kwargs = {
       "opgroup", "condition", "condition_bits", "condition_value"};

pytket/conanfile.py

@@ -32,7 +32,7 @@ def package(self):
         cmake.install()
 
     def requirements(self):
-        self.requires("tket/1.2.39@tket/stable")
+        self.requires("tket/1.2.40@tket/stable")
         self.requires("tklog/0.3.3@tket/stable")
         self.requires("tkrng/0.3.3@tket/stable")
         self.requires("tkassert/0.3.3@tket/stable")

pytket/docs/changelog.rst

@@ -6,7 +6,8 @@ Unreleased
 
 Minor new features:
 
-* Add ``apply_clifford_basis_change_tensor``.
+* ``Circuit.add_conditional_barrier``
+* Add ``apply_clifford_basis_change_tensor`` method
 
 Fixes:
 

pytket/pytket/_tket/circuit.pyi

@@ -8,6 +8,11 @@ import pytket._tket.pauli
 import pytket._tket.unit_id
 import sympy
 
+class BarrierOp(Op):
+    def __init__(self, signature: List[EdgeType], data: str) -> None: ...
+    @property
+    def data(self) -> str: ...
+
 class BasisOrder:
     __members__: ClassVar[dict] = ...  # read-only
     __entries: ClassVar[dict] = ...
@@ -348,6 +353,10 @@ class Circuit:
     def add_classicalexpbox_bit(self, expression: object, target: List[pytket._tket.unit_id.Bit], **kwargs: Any) -> Circuit: ...
     def add_classicalexpbox_register(self, expression: object, target: List[pytket._tket.unit_id.Bit], **kwargs: Any) -> Circuit: ...
     @overload
+    def add_conditional_barrier(self, barrier_qubits: List[int], barrier_bits: List[int], condition_bits: List[int], value: int, data: str = ...) -> Circuit: ...
+    @overload
+    def add_conditional_barrier(self, barrier_args: List[pytket._tket.unit_id.UnitID], condition_bits: List[pytket._tket.unit_id.Bit], value: int, data: str = ...) -> Circuit: ...
+    @overload
     def add_conjugation_box(self, box: ConjugationBox, args: List[pytket._tket.unit_id.UnitID], **kwargs: Any) -> Circuit: ...
     @overload
     def add_conjugation_box(self, box: ConjugationBox, args: List[int], **kwargs: Any) -> Circuit: ...

pytket/pytket/backends/backend.py

@@ -109,7 +109,6 @@ def valid_circuit(self, circuit: Circuit) -> bool:
     def _check_all_circuits(
         self, circuits: Iterable[Circuit], nomeasure_warn: Optional[bool] = None
     ) -> bool:
-
         if nomeasure_warn is None:
             nomeasure_warn = not (
                 self._supports_state
@@ -267,7 +266,6 @@ def process_circuits(
         valid_check: bool = True,
         **kwargs: KwargTypes,
     ) -> List[ResultHandle]:
-
         """
         Submit circuits to the backend for running. The results will be stored
         in the backend's result cache to be retrieved by the corresponding

pytket/pytket/circuit/decompose_classical.py

@@ -342,7 +342,7 @@ def _decompose_expressions(circ: Circuit) -> Tuple[Circuit, bool]:
             modified = True
             continue
         if optype == OpType.Barrier:
-            # add_gate doesn't work for metaops like barrier
+            # add_gate doesn't work for metaops
             newcirc.add_barrier(args)
         else:
             newcirc.add_gate(op, args, **kwargs)

pytket/pytket/qasm/qasm.py

@@ -54,7 +54,7 @@
     MultiBitOp,
     WASMOp,
     CustomGate,
-    MetaOp,
+    BarrierOp,
 )
 from pytket._tket.unit_id import _TEMP_BIT_NAME
 from pytket.circuit import (
@@ -362,9 +362,19 @@ def meas(self, tree: List[Token]) -> Iterable[CommandDict]:
 
     def barr(self, tree: List[Arg]) -> Iterable[CommandDict]:
         args = [q for qs in self.unroll_all_args(tree[0]) for q in qs]
+        signature: List[str] = []
+        for arg in args:
+            if arg[0] in self.c_registers:
+                signature.append("C")
+            elif arg[0] in self.q_registers:
+                signature.append("Q")
+            else:
+                raise QASMParseError(
+                    "UnitID " + str(arg) + " in Barrier arguments is not declared."
+                )
         yield {
             "args": args,
-            "op": {"signature": ["Q"] * len(args), "type": "Barrier"},
+            "op": {"signature": signature, "type": "Barrier"},
         }
 
     def reset(self, tree: List[Token]) -> Iterable[CommandDict]:
@@ -379,7 +389,6 @@ def mixedcall(self, tree: List) -> Iterator[CommandDict]:
 
         optoken = next(child_iter)
         opstr = optoken.value
-
         next_tree = next(child_iter)
         try:
             args = next(child_iter)
@@ -1321,7 +1330,7 @@ def circuit_to_qasm_io(
                     param = -2 + param
             params = [param]  # type: ignore
         elif optype == OpType.Barrier and header == "hqslib1_dev":
-            assert isinstance(op, MetaOp)
+            assert isinstance(op, BarrierOp)
             if op.data == "":
                 opstr = _tk_to_qasm_noparams[optype]
             else:

pytket/tests/classical_test.py

@@ -494,7 +494,6 @@ def qubit_register(
     index=strategies.integers(min_value=0, max_value=32),
 )
 def test_registers(reg: Union[BitRegister, QubitRegister], index: int) -> None:
-
     unit_type = Qubit if type(reg) is QubitRegister else Bit
     if index < reg.size:
         assert reg[index] == unit_type(reg.name, index)

pytket/tests/qasm_test.py

@@ -216,13 +216,29 @@ def test_conditional_gates() -> None:
     circ.Measure(0, 0)
     circ.Measure(1, 1)
     circ.Z(0, condition_bits=[0, 1], condition_value=2)
+    circ.add_conditional_barrier([0, 1], [], [0, 1], 1)
     circ.Measure(0, 0, condition_bits=[0, 1], condition_value=1)
     qasm_out = str(curr_file_path / "qasm_test_files/testout5.qasm")
     circuit_to_qasm(circ, qasm_out)
     c2 = circuit_from_qasm(qasm_out)
     assert circ == c2
 
 
+def test_named_conditional_barrier() -> None:
+    circ = Circuit(2, 2)
+    circ.add_bit(Bit("test", 3))
+    circ.Z(0, condition_bits=[0, 1], condition_value=2)
+    circ.add_conditional_barrier(
+        [Qubit("q", 0), Bit("test", 3)],
+        [Bit("c", 0), Bit("c", 1)],
+        0,
+        data="cond_barrier",
+    )
+    qs_str: str = circuit_to_qasm_str(circ)
+    c_from_qs: Circuit = circuit_from_qasm_str(qs_str)
+    assert qs_str == circuit_to_qasm_str(c_from_qs)
+
+
 def test_hqs_conditional() -> None:
     c = Circuit(1)
     a = c.add_c_register("a", 8)
@@ -273,7 +289,6 @@ def test_barrier() -> None:
     c.H(0)
     c.H(2)
     c.add_barrier([0], [0], "comment")
-
     result = """OPENQASM 2.0;\ninclude "hqslib1_dev.inc";\n\nqreg q[3];
 creg c[3];\nh q[0];\nh q[2];\ncomment q[0],c[0];\n"""
     assert result == circuit_to_qasm_str(c, header="hqslib1_dev")
@@ -773,6 +788,7 @@ def test_rxxyyzz_conversion() -> None:
     test_extended_qasm()
     test_register_commands()
     test_conditional_gates()
+    test_named_conditional_barrier()
     test_hqs_conditional()
     test_hqs_conditional_params()
     test_barrier()

tket/CMakeLists.txt

@@ -111,6 +111,7 @@ target_sources(tket
         src/Clifford/ChoiMixTableau.cpp
         src/Clifford/SymplecticTableau.cpp
         src/Clifford/UnitaryTableau.cpp
+        src/Ops/BarrierOp.cpp
         src/Ops/FlowOp.cpp
         src/Ops/MetaOp.cpp
         src/Ops/Op.cpp
@@ -278,6 +279,7 @@ target_sources(tket
         include/tket/Clifford/SymplecticTableau.hpp
         include/tket/Clifford/UnitaryTableau.hpp
         include/tket/Ops/ClassicalOps.hpp
+        include/tket/Ops/BarrierOp.hpp
         include/tket/Ops/FlowOp.hpp
         include/tket/Ops/MetaOp.hpp
         include/tket/Ops/Op.hpp

tket/conanfile.py

@@ -23,7 +23,7 @@
 
 class TketConan(ConanFile):
     name = "tket"
-    version = "1.2.39"
+    version = "1.2.40"
     package_type = "library"
     license = "Apache 2"
     homepage = "https://github.com/CQCL/tket"

tket/include/tket/Circuit/Circuit.hpp

@@ -836,9 +836,9 @@ class Circuit {
   Vertex add_op(
       OpType type, const std::vector<Expr> &params, const std::vector<ID> &args,
       std::optional<std::string> opgroup = std::nullopt) {
-    if (is_metaop_type(type)) {
+    if (is_metaop_type(type) || is_barrier_type(type)) {
       throw CircuitInvalidity(
-          "Cannot add metaop. Please use `add_barrier` to add a "
+          "Cannot add metaop or barrier. Please use `add_barrier` to add a "
           "barrier.");
     }
     return add_op(get_op_ptr(type, params, args.size()), args, opgroup);
@@ -904,6 +904,11 @@ class Circuit {
     if (is_metaop_type(type)) {
       throw CircuitInvalidity("Cannot add a conditional metaop.");
     }
+    if (is_barrier_type(type)) {
+      throw CircuitInvalidity(
+          "Please use 'add_conditional_barrier' to add a conditional barrier "
+          "gate.");
+    }
     Op_ptr cond = std::make_shared<Conditional>(
         get_op_ptr(type, params, (unsigned)args.size()), (unsigned)bits.size(),
         value);
@@ -918,6 +923,18 @@ class Circuit {
 
   Vertex add_barrier(const unit_vector_t &args, const std::string &_data = "");
 
+  Vertex add_conditional_barrier(
+      const std::vector<unsigned> &barrier_qubits,
+      const std::vector<unsigned> &barrier_bits,
+      const std::vector<unsigned> &condition_bits, unsigned value,
+      const std::string &_data,
+      std::optional<std::string> opgroup = std::nullopt);
+
+  Vertex add_conditional_barrier(
+      const unit_vector_t &barrier_args, const bit_vector_t &condition_bits,
+      unsigned value, const std::string &_data,
+      std::optional<std::string> opgroup = std::nullopt);
+
   /**
    * Add a postfix to a classical register name if the register exists
    * Example: tket_c results in tket_c_2 if tket_c and tket_c_1 both exist

tket/include/tket/Gate/OpPtrFunctions.hpp

@@ -25,8 +25,8 @@ namespace tket {
  *
  * @param chosen_type operation type
  * @param param operation parameter
- * @param n_qubits number of qubits (only necessary for gates and metaops
- *                 with variable quantum arity)
+ * @param n_qubits number of qubits (only necessary for gates, barrier
+ *  and metaops with variable quantum arity)
  */
 Op_ptr get_op_ptr(OpType chosen_type, const Expr &param, unsigned n_qubits = 0);
 
@@ -35,8 +35,8 @@ Op_ptr get_op_ptr(OpType chosen_type, const Expr &param, unsigned n_qubits = 0);
  *
  * @param chosen_type operation type
  * @param params operation parameters
- * @param n_qubits number of qubits (only necessary for gates and metaops
- *                 with variable quantum arity)
+ * @param n_qubits number of qubits (only necessary for gates, barrier
+ *  and metaops with variable quantum arity)
  */
 Op_ptr get_op_ptr(
     OpType chosen_type, const std::vector<Expr> &params = {},

tket/include/tket/OpType/OpDesc.hpp

@@ -61,9 +61,12 @@ class OpDesc {
   /** Number of classical bits written to */
   OptUInt n_classical() const;
 
-  /** Whether the 'operation' is actually an input or output or barrier */
+  /** Whether the 'operation' is actually an input or output */
   bool is_meta() const;
 
+  /** Whether the operation is a Barrier */
+  bool is_barrier() const;
+
   /** Whether the operation is a box of some kind */
   bool is_box() const;
 
@@ -111,6 +114,7 @@ class OpDesc {
   const OpType type_;
   const OpTypeInfo info_;
   const bool is_meta_;
+  const bool is_barrier_;
   const bool is_box_;
   const bool is_gate_;
   const bool is_flowop_;

tket/include/tket/OpType/OpTypeFunctions.hpp

@@ -48,9 +48,12 @@ const OpTypeSet &all_controlled_gate_types();
 /** Set of all classical gates */
 const OpTypeSet &all_classical_types();
 
-/** Test for initial, final and barrier "ops" */
+/** Test for initial and final "ops" */
 bool is_metaop_type(OpType optype);
 
+/** Test for Barrier "ops" */
+bool is_barrier_type(OpType optype);
+
 /** Test for input or creation quantum "ops" */
 bool is_initial_q_type(OpType optype);