Add flag to latex drawer to enable label passthrough

This commit adds a new flag latex_labels to the circuit_drawer for use
with the latex and latex_source drawer. When it is set to true it
disables the pylatexenc conversion from unicode input to a latex
encoding. This enables users who want to manual create gate names that
are properly latex encoded (for example to have gate names with
subscripts) to do so.

Fixes #3171

qiskit/circuit/quantumcircuit.py

@@ -561,7 +561,7 @@ def qasm(self):
     def draw(self, scale=0.7, filename=None, style=None, output=None,
              interactive=False, line_length=None, plot_barriers=True,
              reverse_bits=False, justify=None, vertical_compression='medium', idle_wires=True,
-             with_layout=True):
+             with_layout=True, latex_labels=False):
         """Draw the quantum circuit
 
         Using the output parameter you can specify the format. The choices are:
@@ -604,6 +604,10 @@ def draw(self, scale=0.7, filename=None, style=None, output=None,
             idle_wires (bool): Include idle wires. Default is True.
             with_layout (bool): Include layout information, with labels on the physical
                 layout. Default is True.
+            latex_labels (bool): When set to true input labels from the circuit
+                are treated as already encoded for latex and no conversion is
+                performed. (latex and latex_source only)
+
         Returns:
             PIL.Image or matplotlib.figure or str or TextDrawing:
                 * PIL.Image: (output `latex`) an in-memory representation of the
@@ -629,7 +633,8 @@ def draw(self, scale=0.7, filename=None, style=None, output=None,
                               justify=justify,
                               vertical_compression=vertical_compression,
                               idle_wires=idle_wires,
-                              with_layout=with_layout)
+                              with_layout=with_layout,
+                              latex_labels=latex_labels)
 
     def size(self):
         """Returns total number of gate operations in circuit.

qiskit/visualization/circuit_visualization.py

@@ -56,7 +56,8 @@ def circuit_drawer(circuit,
                    justify=None,
                    vertical_compression='medium',
                    idle_wires=True,
-                   with_layout=True):
+                   with_layout=True,
+                   latex_labels=False):
     """Draw a quantum circuit to different formats (set by output parameter):
     0. text: ASCII art TextDrawing that can be printed in the console.
     1. latex: high-quality images, but heavy external software dependencies
@@ -102,6 +103,9 @@ def circuit_drawer(circuit,
         idle_wires (bool): Include idle wires. Default is True.
         with_layout (bool): Include layout information, with labels on the physical
             layout.
+        latex_labels (bool): When set to true input labels from the circuit
+            are treated as already encoded for latex and no conversion is
+            performed. (latex and latex_source only)
     Returns:
         PIL.Image: (output `latex`) an in-memory representation of the image
             of the circuit diagram.
@@ -237,7 +241,8 @@ def circuit_drawer(circuit,
                                       reverse_bits=reverse_bits,
                                       justify=justify,
                                       idle_wires=idle_wires,
-                                      with_layout=with_layout)
+                                      with_layout=with_layout,
+                                      latex_labels=latex_labels)
     elif output == 'latex_source':
         return _generate_latex_source(circuit,
                                       filename=filename, scale=scale,
@@ -246,7 +251,8 @@ def circuit_drawer(circuit,
                                       reverse_bits=reverse_bits,
                                       justify=justify,
                                       idle_wires=idle_wires,
-                                      with_layout=with_layout)
+                                      with_layout=with_layout,
+                                      latex_labels=latex_labels)
     elif output == 'mpl':
         image = _matplotlib_circuit_drawer(circuit, scale=scale,
                                            filename=filename, style=style,
@@ -396,7 +402,8 @@ def _latex_circuit_drawer(circuit,
                           reverse_bits=False,
                           justify=None,
                           idle_wires=True,
-                          with_layout=True):
+                          with_layout=True,
+                          latex_labels=False):
     """Draw a quantum circuit based on latex (Qcircuit package)
 
     Requires version >=2.6.0 of the qcircuit LaTeX package.
@@ -415,6 +422,10 @@ def _latex_circuit_drawer(circuit,
         idle_wires (bool): Include idle wires. Default is True.
         with_layout (bool): Include layout information, with labels on the physical
             layout. Default: True
+        latex_labels (bool): When set to true input labels from the circuit
+            are treated as already encoded for latex and no conversion is
+            performed.
+
     Returns:
         PIL.Image: an in-memory representation of the circuit diagram
 
@@ -431,7 +442,8 @@ def _latex_circuit_drawer(circuit,
                                scale=scale, style=style,
                                plot_barriers=plot_barriers,
                                reverse_bits=reverse_bits, justify=justify,
-                               idle_wires=idle_wires, with_layout=with_layout)
+                               idle_wires=idle_wires, with_layout=with_layout,
+                               latex_labels=latex_labels)
         try:
 
             subprocess.run(["pdflatex", "-halt-on-error",
@@ -478,7 +490,7 @@ def _latex_circuit_drawer(circuit,
 def _generate_latex_source(circuit, filename=None,
                            scale=0.7, style=None, reverse_bits=False,
                            plot_barriers=True, justify=None, idle_wires=True,
-                           with_layout=True):
+                           with_layout=True, latex_labels=False):
     """Convert QuantumCircuit to LaTeX string.
 
     Args:
@@ -495,6 +507,10 @@ def _generate_latex_source(circuit, filename=None,
         idle_wires (bool): Include idle wires. Default is True.
         with_layout (bool): Include layout information, with labels on the physical
             layout. Default: True
+        latex_labels (bool): When set to true input labels from the circuit
+            are treated as already encoded for latex and no conversion is
+            performed.
+
     Returns:
         str: Latex string appropriate for writing to file.
     """
@@ -508,7 +524,8 @@ def _generate_latex_source(circuit, filename=None,
 
     qcimg = _latex.QCircuitImage(qregs, cregs, ops, scale, style=style,
                                  plot_barriers=plot_barriers,
-                                 reverse_bits=reverse_bits, layout=layout)
+                                 reverse_bits=reverse_bits, layout=layout,
+                                 latex_labels=latex_labels)
     latex = qcimg.latex()
     if filename:
         with open(filename, 'w') as latex_file:

qiskit/visualization/latex.py

@@ -45,7 +45,8 @@ class QCircuitImage:
     """
 
     def __init__(self, qubits, clbits, ops, scale, style=None,
-                 plot_barriers=True, reverse_bits=False, layout=None):
+                 plot_barriers=True, reverse_bits=False, layout=None,
+                 latex_labels=False):
         """
         Args:
             qubits (list[Qubit]): list of qubits
@@ -59,6 +60,9 @@ def __init__(self, qubits, clbits, ops, scale, style=None,
                circuit. Defaults to True.
             layout (Layout or None): If present, the layout information will be
                included.
+            latex_labels (bool): When set to true input labels from the circuit
+                are treated as already encoded for latex and no conversion is
+                performed.
         Raises:
             ImportError: If pylatexenc is not installed
         """
@@ -122,6 +126,7 @@ def __init__(self, qubits, clbits, ops, scale, style=None,
         self.reverse_bits = reverse_bits
         self.layout = layout
         self.plot_barriers = plot_barriers
+        self.latex_labels = latex_labels
 
         #################################
         self.qregs = _get_register_specs(qubits)
@@ -367,7 +372,10 @@ def _build_latex_array(self, aliases=None):
                                       'b').zfill(self.cregs[if_reg])[::-1]
                 if op.name not in ['measure', 'barrier', 'snapshot', 'load',
                                    'save', 'noise']:
-                    nm = utf8tolatex(op.name).replace(" ", "\\,")
+                    if not self.latex_labels:
+                        nm = utf8tolatex(op.name).replace(" ", "\\,")
+                    else:
+                        nm = op.name
                     qarglist = op.qargs
                     if aliases is not None:
                         qarglist = map(lambda x: aliases[x], qarglist)

releasenotes/notes/latex-labels-9f41997194ef753b.yaml

@@ -0,0 +1,11 @@
+---
+features:
+  - |
+    A new boolean kwarg flag, ``latex_labels``, has been added to
+    ``qiskit.visualization.circuit_drawer`` and ``qiskit.QuantumCircuit.draw``.
+    This flag only is used by the ``latex`` and ``latex_source`` circuit drawer
+    backends. When set on all other backends it will be ignored. When this flag
+    is set to ``True`` with the latex drawers it will disable the automated
+    conversion of input gate names from unicode to a latex encoding. This
+    enables users who want to manually format gate names for rendering in latex
+    to do so.