Add CZSWAP gate and optimize stim.PauliString.{after,before}

doc/gates.md

@@ -26,6 +26,7 @@
     - [CXSWAP](#CXSWAP)
     - [CY](#CY)
     - [CZ](#CZ)
+    - [CZSWAP](#CZSWAP)
     - [ISWAP](#ISWAP)
     - [ISWAP_DAG](#ISWAP_DAG)
     - [SQRT_XX](#SQRT_XX)
@@ -36,6 +37,7 @@
     - [SQRT_ZZ_DAG](#SQRT_ZZ_DAG)
     - [SWAP](#SWAP)
     - [SWAPCX](#SWAPCX)
+    - [SWAPCZ](#SWAPCZ)
     - [XCX](#XCX)
     - [XCY](#XCY)
     - [XCZ](#XCZ)
@@ -1103,6 +1105,51 @@ Decomposition (into H, S, CX, M, R):
     H 1
 
 
+<a name="CZSWAP"></a>
+### The 'CZSWAP' Gate
+
+Alternate name: <a name="SWAPCZ"></a>`SWAPCZ`
+
+A combination CZ-and-SWAP gate.
+This gate is kak-equivalent to the iswap gate.
+
+Parens Arguments:
+
+    This instruction takes no parens arguments.
+
+Targets:
+
+    Qubit pairs to operate on.
+
+Example:
+
+    CZSWAP 5 6
+    CZSWAP 42 43
+    CZSWAP 5 6 42 43
+
+Stabilizer Generators:
+
+    X_ -> ZX
+    Z_ -> _Z
+    _X -> XZ
+    _Z -> Z_
+
+Unitary Matrix (little endian):
+
+    [+1  ,     ,     ,     ]
+    [    ,     , +1  ,     ]
+    [    , +1  ,     ,     ]
+    [    ,     ,     , -1  ]
+
+Decomposition (into H, S, CX, M, R):
+
+    # The following circuit is equivalent (up to global phase) to `CZSWAP 0 1`
+    H 0
+    CX 0 1
+    CX 1 0
+    H 1
+
+
 <a name="ISWAP"></a>
 ### The 'ISWAP' Gate
 

file_lists/benchmark_files

@@ -1,7 +1,7 @@
 src/stim/benchmark_main.perf.cc
 src/stim/benchmark_util.perf.cc
 src/stim/circuit/circuit.perf.cc
-src/stim/circuit/gate_data.perf.cc
+src/stim/gates/gates.perf.cc
 src/stim/io/measure_record_reader.perf.cc
 src/stim/main_namespaced.perf.cc
 src/stim/mem/simd_bit_table.perf.cc

file_lists/python_api_files

@@ -1,13 +1,13 @@
 src/stim/circuit/circuit.pybind.cc
 src/stim/circuit/circuit_instruction.pybind.cc
 src/stim/circuit/circuit_repeat_block.pybind.cc
-src/stim/circuit/gate_data.pybind.cc
 src/stim/circuit/gate_target.pybind.cc
 src/stim/cmd/command_diagram.pybind.cc
 src/stim/dem/detector_error_model.pybind.cc
 src/stim/dem/detector_error_model_instruction.pybind.cc
 src/stim/dem/detector_error_model_repeat_block.pybind.cc
 src/stim/dem/detector_error_model_target.pybind.cc
+src/stim/gates/gates.pybind.cc
 src/stim/io/read_write.pybind.cc
 src/stim/py/base.pybind.cc
 src/stim/py/compiled_detector_sampler.pybind.cc

file_lists/source_files_no_main

@@ -3,20 +3,6 @@ src/stim/arg_parse.cc
 src/stim/circuit/circuit.cc
 src/stim/circuit/circuit_instruction.cc
 src/stim/circuit/export_qasm.cc
-src/stim/circuit/gate_data.cc
-src/stim/circuit/gate_data_annotations.cc
-src/stim/circuit/gate_data_blocks.cc
-src/stim/circuit/gate_data_collapsing.cc
-src/stim/circuit/gate_data_controlled.cc
-src/stim/circuit/gate_data_hada.cc
-src/stim/circuit/gate_data_heralded.cc
-src/stim/circuit/gate_data_noisy.cc
-src/stim/circuit/gate_data_pair_measure.cc
-src/stim/circuit/gate_data_pauli.cc
-src/stim/circuit/gate_data_period_3.cc
-src/stim/circuit/gate_data_period_4.cc
-src/stim/circuit/gate_data_pp.cc
-src/stim/circuit/gate_data_swaps.cc
 src/stim/circuit/gate_decomposition.cc
 src/stim/circuit/gate_target.cc
 src/stim/cmd/command_analyze_errors.cc
@@ -51,6 +37,20 @@ src/stim/diagram/lattice_map.cc
 src/stim/diagram/timeline/timeline_3d_drawer.cc
 src/stim/diagram/timeline/timeline_ascii_drawer.cc
 src/stim/diagram/timeline/timeline_svg_drawer.cc
+src/stim/gates/gate_data_annotations.cc
+src/stim/gates/gate_data_blocks.cc
+src/stim/gates/gate_data_collapsing.cc
+src/stim/gates/gate_data_controlled.cc
+src/stim/gates/gate_data_hada.cc
+src/stim/gates/gate_data_heralded.cc
+src/stim/gates/gate_data_noisy.cc
+src/stim/gates/gate_data_pair_measure.cc
+src/stim/gates/gate_data_pauli.cc
+src/stim/gates/gate_data_period_3.cc
+src/stim/gates/gate_data_period_4.cc
+src/stim/gates/gate_data_pp.cc
+src/stim/gates/gate_data_swaps.cc
+src/stim/gates/gates.cc
 src/stim/gen/circuit_gen_params.cc
 src/stim/gen/gen_color_code.cc
 src/stim/gen/gen_rep_code.cc

file_lists/test_files

@@ -2,7 +2,6 @@ src/stim.test.cc
 src/stim/arg_parse.test.cc
 src/stim/circuit/circuit.test.cc
 src/stim/circuit/export_qasm.test.cc
-src/stim/circuit/gate_data.test.cc
 src/stim/circuit/gate_decomposition.test.cc
 src/stim/circuit/gate_target.test.cc
 src/stim/circuit/stabilizer_flow.test.cc
@@ -26,6 +25,7 @@ src/stim/diagram/json_obj.test.cc
 src/stim/diagram/timeline/timeline_3d_drawer.test.cc
 src/stim/diagram/timeline/timeline_ascii_drawer.test.cc
 src/stim/diagram/timeline/timeline_svg_drawer.test.cc
+src/stim/gates/gates.test.cc
 src/stim/gen/circuit_gen_params.test.cc
 src/stim/gen/gen_color_code.test.cc
 src/stim/gen/gen_rep_code.test.cc
@@ -74,6 +74,7 @@ src/stim/stabilizers/conversions.test.cc
 src/stim/stabilizers/flex_pauli_string.test.cc
 src/stim/stabilizers/pauli_string.test.cc
 src/stim/stabilizers/pauli_string_iter.test.cc
+src/stim/stabilizers/pauli_string_ref.test.cc
 src/stim/stabilizers/tableau.test.cc
 src/stim/stabilizers/tableau_iter.test.cc
 src/stim/str_util.test.cc

glue/cirq/stimcirq/__init__.py

@@ -1,6 +1,7 @@
 __version__ = '1.13.dev0'
 from ._cirq_to_stim import cirq_circuit_to_stim_circuit
 from ._cx_swap_gate import CXSwapGate
+from ._cz_swap_gate import CZSwapGate
 from ._det_annotation import DetAnnotation
 from ._obs_annotation import CumulativeObservableAnnotation
 from ._shift_coords_annotation import ShiftCoordsAnnotation
@@ -20,5 +21,6 @@
     "SweepPauli": SweepPauli,
     "TwoQubitAsymmetricDepolarizingChannel": TwoQubitAsymmetricDepolarizingChannel,
     "CXSwapGate": CXSwapGate,
+    "CZSwapGate": CZSwapGate,
 }
 JSON_RESOLVER = JSON_RESOLVERS_DICT.get

glue/cirq/stimcirq/_cz_swap_gate.py

@@ -0,0 +1,46 @@
+from typing import Any, Dict, List
+
+import cirq
+import stim
+
+
+@cirq.value_equality
+class CZSwapGate(cirq.Gate):
+    """Handles explaining stim's CZSWAP gates to cirq."""
+
+    def _num_qubits_(self) -> int:
+        return 2
+
+    def _circuit_diagram_info_(self, args: cirq.CircuitDiagramInfoArgs) -> List[str]:
+        return ['ZSWAP', 'ZSWAP']
+
+    def _value_equality_values_(self):
+        return ()
+
+    def _decompose_(self, qubits):
+        a, b = qubits
+        yield cirq.SWAP(a, b)
+        yield cirq.CZ(a, b)
+
+    def _stim_conversion_(self, edit_circuit: stim.Circuit, targets: List[int], **kwargs):
+        edit_circuit.append_operation('CZSWAP', targets)
+
+    def __pow__(self, power: int) -> 'CZSwapGate':
+        if power == +1:
+            return self
+        if power == -1:
+            return self
+        return NotImplemented
+
+    def __str__(self) -> str:
+        return 'CZSWAP'
+
+    def __repr__(self):
+        return f'stimcirq.CZSwapGate()'
+
+    @staticmethod
+    def _json_namespace_() -> str:
+        return ''
+
+    def _json_dict_(self) -> Dict[str, Any]:
+        return {}

glue/cirq/stimcirq/_cz_swap_test.py

@@ -0,0 +1,72 @@
+import cirq
+import stim
+import stimcirq
+
+
+def test_stim_conversion():
+    a, b, c = cirq.LineQubit.range(3)
+
+    cirq_circuit = cirq.Circuit(
+        stimcirq.CZSwapGate().on(a, b),
+        stimcirq.CZSwapGate().on(b, c),
+    )
+    stim_circuit = stim.Circuit(
+        """
+        CZSWAP 0 1
+        TICK
+        CZSWAP 1 2
+        TICK
+        """
+    )
+    assert stimcirq.cirq_circuit_to_stim_circuit(cirq_circuit) == stim_circuit
+    assert stimcirq.stim_circuit_to_cirq_circuit(stim_circuit) == cirq_circuit
+
+
+def test_diagram():
+    a, b = cirq.LineQubit.range(2)
+    cirq.testing.assert_has_diagram(
+        cirq.Circuit(
+            stimcirq.CZSwapGate()(a, b),
+            stimcirq.CZSwapGate()(a, b),
+        ),
+        """
+0: ---ZSWAP---ZSWAP---
+      |       |
+1: ---ZSWAP---ZSWAP---
+        """,
+        use_unicode_characters=False,
+    )
+
+
+def test_inverse():
+    a = stimcirq.CZSwapGate()
+    assert a**+1 == a
+    assert a**-1 == a
+
+
+def test_repr():
+    val = stimcirq.CZSwapGate()
+    assert eval(repr(val), {"stimcirq": stimcirq}) == val
+
+
+def test_equality():
+    eq = cirq.testing.EqualsTester()
+    eq.add_equality_group(stimcirq.CZSwapGate(), stimcirq.CZSwapGate())
+
+
+def test_json_serialization():
+    a, b, d = cirq.LineQubit.range(3)
+    c = cirq.Circuit(
+        stimcirq.CZSwapGate()(a, b),
+        stimcirq.CZSwapGate()(b, d),
+    )
+    json = cirq.to_json(c)
+    c2 = cirq.read_json(json_text=json, resolvers=[*cirq.DEFAULT_RESOLVERS, stimcirq.JSON_RESOLVER])
+    assert c == c2
+
+
+def test_json_backwards_compat_exact():
+    raw = stimcirq.CZSwapGate()
+    packed = '{\n  "cirq_type": "CZSwapGate"\n}'
+    assert cirq.to_json(raw) == packed
+    assert cirq.read_json(json_text=packed, resolvers=[*cirq.DEFAULT_RESOLVERS, stimcirq.JSON_RESOLVER]) == raw

glue/cirq/stimcirq/_stim_to_cirq.py

@@ -16,6 +16,7 @@
 import stim
 
 from ._cx_swap_gate import CXSwapGate
+from ._cz_swap_gate import CZSwapGate
 from ._det_annotation import DetAnnotation
 from ._measure_and_or_reset_gate import MeasureAndOrResetGate
 from ._obs_annotation import CumulativeObservableAnnotation
@@ -424,6 +425,7 @@ def handler(
                     measure=False, reset=True, basis='X', invert_measure=False, key=''
                 )
             ),
+            "CZSWAP": gate(CZSwapGate()),
             "CXSWAP": gate(CXSwapGate(inverted=False)),
             "SWAPCX": gate(CXSwapGate(inverted=True)),
             "RY": gate(

glue/javascript/tableau.js.cc

@@ -3,7 +3,7 @@
 #include <emscripten/bind.h>
 
 #include "common.js.h"
-#include "stim/circuit/gate_data.h"
+#include "stim/gates/gates.h"
 
 using namespace stim;
 

src/stim.h

@@ -7,8 +7,6 @@
 #include "stim/circuit/circuit.h"
 #include "stim/circuit/circuit_instruction.h"
 #include "stim/circuit/export_qasm.h"
-#include "stim/circuit/gate_data.h"
-#include "stim/circuit/gate_data_table.h"
 #include "stim/circuit/gate_decomposition.h"
 #include "stim/circuit/gate_target.h"
 #include "stim/circuit/stabilizer_flow.h"
@@ -45,6 +43,7 @@
 #include "stim/diagram/timeline/timeline_3d_drawer.h"
 #include "stim/diagram/timeline/timeline_ascii_drawer.h"
 #include "stim/diagram/timeline/timeline_svg_drawer.h"
+#include "stim/gates/gates.h"
 #include "stim/gen/circuit_gen_params.h"
 #include "stim/gen/gen_color_code.h"
 #include "stim/gen/gen_rep_code.h"

src/stim/circuit/circuit.cc

@@ -14,11 +14,12 @@
 
 #include "stim/circuit/circuit.h"
 
+#include <algorithm>
 #include <string>
 #include <utility>
 
-#include "stim/circuit/gate_data.h"
 #include "stim/circuit/gate_target.h"
+#include "stim/gates/gates.h"
 #include "stim/str_util.h"
 
 using namespace stim;

src/stim/circuit/circuit.h

@@ -28,8 +28,8 @@
 #include <vector>
 
 #include "stim/circuit/circuit_instruction.h"
-#include "stim/circuit/gate_data.h"
 #include "stim/circuit/gate_target.h"
+#include "stim/gates/gates.h"
 #include "stim/mem/monotonic_buffer.h"
 #include "stim/mem/span_ref.h"
 

src/stim/circuit/circuit.test.cc

@@ -1619,6 +1619,7 @@ Circuit stim::generate_test_circuit_with_all_operations() {
         ISWAP_DAG 4 5
         SWAP 6 7
         SWAPCX 8 9
+        CZSWAP 10 11
         SQRT_XX 0 1
         SQRT_XX_DAG 2 3
         SQRT_YY 4 5

src/stim/circuit/circuit_instruction.cc

@@ -17,8 +17,8 @@
 #include <utility>
 
 #include "stim/circuit/circuit.h"
-#include "stim/circuit/gate_data.h"
 #include "stim/circuit/gate_target.h"
+#include "stim/gates/gates.h"
 
 using namespace stim;
 

src/stim/circuit/circuit_instruction.pybind.cc

@@ -14,8 +14,8 @@
 
 #include "stim/circuit/circuit_instruction.pybind.h"
 
-#include "stim/circuit/gate_data.h"
 #include "stim/circuit/gate_target.pybind.h"
+#include "stim/gates/gates.h"
 #include "stim/py/base.pybind.h"
 #include "stim/str_util.h"
 

src/stim/circuit/circuit_instruction.pybind.h

@@ -18,8 +18,8 @@
 #include <pybind11/pybind11.h>
 
 #include "stim/circuit/circuit_instruction.h"
-#include "stim/circuit/gate_data.h"
 #include "stim/circuit/gate_target.h"
+#include "stim/gates/gates.h"
 
 namespace stim_pybind {