Support common notations in circuit_to_latex_using_qcircuit - PR for Issue #4685

cirq-core/cirq/contrib/qcircuit/pdf_test_files/test_pdf.tex

@@ -0,0 +1,21 @@
+\documentclass{article}%
+\usepackage[T1]{fontenc}%
+\usepackage[utf8]{inputenc}%
+\usepackage{lmodern}%
+\usepackage{textcomp}%
+\usepackage{lastpage}%
+\usepackage{amsmath}%
+\usepackage{qcircuit}%
+%
+\usepackage[utf8]{inputenc}%
+%
+\begin{document}%
+\normalsize%
+\Qcircuit @R=1em @C=0.75em {
+ \\
+ &\lstick{\text{q(0)}}& \qw&\ctrlo{} \qw    &\control \qw    &\targ    \qw    &\qswap     \qw&           \qw&\qw\\
+ &\lstick{\text{q(1)}}& \qw&\control \qw\qwx&\targ    \qw\qwx&\ctrlo{} \qw\qwx&\qswap\qwx \qw&\qswap     \qw&\qw\\
+ &\lstick{\text{q(2)}}& \qw&\targ    \qw\qwx&\ctrlo{} \qw\qwx&\control \qw\qwx&           \qw&\qswap\qwx \qw&\qw\\
+ \\
+}%
+\end{document}

cirq-core/cirq/contrib/qcircuit/qcircuit_diagram_info.py

@@ -33,6 +33,10 @@ def escape_text_for_latex(text):
     return r'\text{' + escaped + '}'
 
 
+def escape_text_for_latex_custom_control_gate(text):
+    return text.replace('(0)', r'\ctrlo{}').replace('@', r'\control').replace('X', r'\targ')
+
+
 def get_multigate_parameters(args: protocols.CircuitDiagramInfoArgs) -> Optional[Tuple[int, int]]:
     if (args.label_map is None) or (args.known_qubits is None):
         return None
@@ -67,10 +71,20 @@ def hardcoded_qcircuit_diagram_info(op: ops.Operation) -> Optional[protocols.Cir
 def convert_text_diagram_info_to_qcircuit_diagram_info(
     info: protocols.CircuitDiagramInfo,
 ) -> protocols.CircuitDiagramInfo:
-    labels = [escape_text_for_latex(e) for e in info.wire_symbols]
-    if info.exponent != 1:
-        labels[0] += '^{' + str(info.exponent) + '}'
-    symbols = tuple(r'\gate{' + l + '}' for l in labels)
+    symbols = None
+    if (
+        len(info.wire_symbols) == 3
+        and '(0)' in info.wire_symbols
+        and '@' in info.wire_symbols
+        and 'X' in info.wire_symbols
+    ):
+        labels = [escape_text_for_latex_custom_control_gate(e) for e in info.wire_symbols]
+        symbols = tuple(l for l in labels)
+    else:
+        labels = [escape_text_for_latex(e) for e in info.wire_symbols]
+        if info.exponent != 1:
+            labels[0] += '^{' + str(info.exponent) + '}'
+        symbols = tuple(r'\gate{' + l + '}' for l in labels)
     return protocols.CircuitDiagramInfo(symbols)
 
 
@@ -89,17 +103,30 @@ def multigate_qcircuit_diagram_info(
     info = protocols.circuit_diagram_info(op, args, default=None)
 
     min_index, n_qubits = multigate_parameters
-    name = escape_text_for_latex(
-        str(op.gate).rsplit('**', 1)[0] if isinstance(op, ops.GateOperation) else str(op)
-    )
-    if (info is not None) and (info.exponent != 1):
-        name += '^{' + str(info.exponent) + '}'
-    box = r'\multigate{' + str(n_qubits - 1) + '}{' + name + '}'
-    ghost = r'\ghost{' + name + '}'
+
+    symbols = None
     assert args.label_map is not None
     assert args.known_qubits is not None
-    symbols = tuple(box if (args.label_map[q] == min_index) else ghost for q in args.known_qubits)
-    # Force exponent=1 to defer to exponent formatting given above.
+
+    if op.gate == ops.SWAP:
+        box = r'\qswap'
+        ghost = r'\qswap\qwx'
+        symbols = tuple(
+            box if (args.label_map[q] == min_index) else ghost for q in args.known_qubits
+        )
+    else:
+        name = escape_text_for_latex(
+            str(op.gate).rsplit('**', 1)[0] if isinstance(op, ops.GateOperation) else str(op)
+        )
+        if (info is not None) and (info.exponent != 1):
+            name += '^{' + str(info.exponent) + '}'
+        box = r'\multigate{' + str(n_qubits - 1) + '}{' + name + '}'
+        ghost = r'\ghost{' + name + '}'
+        symbols = tuple(
+            box if (args.label_map[q] == min_index) else ghost for q in args.known_qubits
+        )
+        # Force exponent=1 to defer to exponent formatting given above.
+
     return protocols.CircuitDiagramInfo(symbols, connected=False)
 
 

cirq-core/cirq/contrib/qcircuit/qcircuit_diagram_info_test.py

@@ -47,9 +47,7 @@ def test_get_qcircuit_diagram_info():
         label_map=qubit_map,
     )
     actual_info = ccq.get_qcircuit_diagram_info(op, args)
-    expected_info = cirq.CircuitDiagramInfo(
-        (r'\ghost{\text{SWAP}}', r'\multigate{1}{\text{SWAP}}'), connected=False
-    )
+    expected_info = cirq.CircuitDiagramInfo((r'\qswap\qwx', r'\qswap'), connected=False)
     assert actual_info == expected_info
 
     qubit_map = {q: i for q, i in zip(qubits, (2, 5))}

cirq-core/cirq/contrib/qcircuit/qcircuit_test.py

@@ -16,6 +16,8 @@
 import cirq.contrib.qcircuit as ccq
 import cirq.testing as ct
 
+# import cirq.contrib.qcircuit.qcircuit_pdf as pdf
+
 
 def assert_has_qcircuit_diagram(actual: cirq.Circuit, desired: str, **kwargs) -> None:
     """Determines if a given circuit has the desired qcircuit diagram.
@@ -165,3 +167,66 @@ def test_sqrt_iswap_diagram():
  \\
 }""".strip()
     assert_has_qcircuit_diagram(circuit, expected_diagram)
+
+
+def test_latex_formatting():
+    # test for proper rendering of failing latex formats
+    q0, q1, q2 = cirq.LineQubit.range(3)
+
+    # custom gate with a control for zero and one
+    custom_gate = cirq.X.controlled(2, control_values=(0, 1))
+
+    circuit = cirq.Circuit(
+        custom_gate(q0, q1, q2),
+        custom_gate(q2, q0, q1),
+        custom_gate(q1, q2, q0),
+        cirq.SWAP(q0, q1),
+        cirq.SWAP(q1, q2),
+    )
+
+    expected_diagram = r"""
+\Qcircuit @R=1em @C=0.75em {
+ \\
+ &\lstick{\text{q(0)}}& \qw&\ctrlo{} \qw    &\control \qw    &\targ    \qw    &\qswap     \qw&           \qw&\qw\\
+ &\lstick{\text{q(1)}}& \qw&\control \qw\qwx&\targ    \qw\qwx&\ctrlo{} \qw\qwx&\qswap\qwx \qw&\qswap     \qw&\qw\\
+ &\lstick{\text{q(2)}}& \qw&\targ    \qw\qwx&\ctrlo{} \qw\qwx&\control \qw\qwx&           \qw&\qswap\qwx \qw&\qw\\
+ \\
+}""".strip()
+
+    assert_has_qcircuit_diagram(circuit, expected_diagram)
+
+
+# def test_pdf_custom_gates():
+#     # test for proper rendering of failing latex formats in a pdf
+#     q0, q1, q2 = cirq.LineQubit.range(3)
+
+#     # custom gate with a control for zero and one
+#     custom_gate = cirq.X.controlled(2, control_values=(0, 1))
+
+#     circuit = cirq.Circuit(
+#         custom_gate(q0, q1, q2),
+#         custom_gate(q2, q0, q1),
+#         custom_gate(q1, q2, q0),
+#         cirq.SWAP(q0, q1),
+#         cirq.SWAP(q1, q2),
+#     )
+
+#     pdf_kwargs = {
+#         'compiler': 'latexmk',
+#         'compiler_args': ['-pdf', '-f', '-pdflatex=xelatex', '-quiet'],
+#     }
+
+#     remove = ['aux', 'fdb_latexmk', 'fls', 'log']
+
+#     # This test was facing errors due to technical issues in qcuircuit_pdf.py
+#     # that are out of scope of my issue (4685)
+#     # It will remain commented out until a resolution is found,
+#     # or until it is realized that this test is not necessary
+
+#     pdf.circuit_to_pdf_using_qcircuit_via_tex(
+#         circuit,
+#         "./cirq-core/cirq/contrib/qcircuit/pdf_test_files/test",
+#         pdf_kwargs,
+#         None,
+#         remove
+#     )