Change qubit str representation (#5343)

* Change qubit str representation - Changes grid qubit string representation from (x, y) to q(x, y) and line qubit from 1 to q1. - This will make the string representation more distinctive. - Added _circuit_diagram_info_ for Qid objects to make circuit diagrams customizable for qubits. This allows us to keep circuit diagrams largely unchanged. - Other components such as pauli strings, that rely on qubit str representation for formatting are changed. This is a BREAKING CHANGE for anyone relying on string representation of qubits. Fixes: #2405 * Fix a bunch of tests. * A few more errors. * Switch to q(0) and fix a bunch of tests. * Formatting and more tests fixed. * Fix more tests. * Fix two last tests. * Fix bb84 example. * Fix contrib and notebook tests. * Update cirq-core/cirq/sim/simulator_test.py Co-authored-by: Matthew Neeley <mneeley@gmail.com> * Update cirq-core/cirq/circuits/circuit.py Co-authored-by: Matthew Neeley <mneeley@gmail.com> * Revert Grid Device to use circuit diagram names instead. Co-authored-by: Matthew Neeley <mneeley@gmail.com>
quantumlib · May 16, 2022 · 2d84676 · 2d84676
1 parent b1a5a39
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Showing 40 changed files with 314 additions and 262 deletions.
diff --git a/cirq-core/cirq/circuits/circuit.py b/cirq-core/cirq/circuits/circuit.py
@@ -1187,7 +1187,7 @@ def to_text_diagram_drawer(
         Args:
             use_unicode_characters: Determines if unicode characters are
                 allowed (as opposed to ascii-only diagrams).
-            qubit_namer: Names qubits in diagram. Defaults to str.
+            qubit_namer: Names qubits in diagram. Defaults to using _circuit_diagram_info_ or str.
             transpose: Arranges qubit wires vertically instead of horizontally.
             include_tags: Whether to include tags in the operation.
             draw_moment_groups: Whether to draw moment symbol or not
@@ -1210,7 +1210,9 @@ def to_text_diagram_drawer(
         label_map = {labels[i]: i for i in range(len(labels))}
 
         def default_namer(label_entity):
-            return str(label_entity) + ('' if transpose else ': ')
+            info = protocols.circuit_diagram_info(label_entity, default=None)
+            qubit_name = info.wire_symbols[0] if info else str(label_entity)
+            return qubit_name + ('' if transpose else ': ')
 
         if qubit_namer is None:
             qubit_namer = default_namer

diff --git a/cirq-core/cirq/circuits/circuit_operation_test.py b/cirq-core/cirq/circuits/circuit_operation_test.py
@@ -577,7 +577,7 @@ def test_string_format():
         == f"""\
 [ 0: ───X───X─── ]
 [           │    ]
-[ 1: ───H───@─── ](qubit_map={{1: 2}}, parent_path=('outer', 'inner'),\
+[ 1: ───H───@─── ](qubit_map={{q(1): q(2)}}, parent_path=('outer', 'inner'),\
  repetition_ids=['a', 'b', 'c'])"""
     )
     assert (
@@ -611,7 +611,7 @@ def test_string_format():
     assert (
         str(op3)
         == f"""\
-[ 0: ───X^b───M('m')─── ](qubit_map={{0: 1}}, \
+[ 0: ───X^b───M('m')─── ](qubit_map={{q(0): q(1)}}, \
 key_map={{m: p}}, params={{b: 2}})"""
     )
     assert (

diff --git a/cirq-core/cirq/circuits/qasm_output_test.py b/cirq-core/cirq/circuits/qasm_output_test.py
@@ -563,7 +563,7 @@ def test_reset():
 include "qelib1.inc";
 
 
-// Qubits: [0, 1]
+// Qubits: [q(0), q(1)]
 qreg q[2];
 
 

diff --git a/cirq-core/cirq/contrib/qcircuit/qcircuit_test.py b/cirq-core/cirq/contrib/qcircuit/qcircuit_test.py
@@ -118,9 +118,9 @@ def test_other_diagram():
     expected_diagram = r"""
 \Qcircuit @R=1em @C=0.75em {
  \\
- &\lstick{\text{0}}& \qw&\targ           \qw&\qw\\
- &\lstick{\text{1}}& \qw&\gate{\text{Y}} \qw&\qw\\
- &\lstick{\text{2}}& \qw&\gate{\text{Z}} \qw&\qw\\
+ &\lstick{\text{q(0)}}& \qw&\targ           \qw&\qw\\
+ &\lstick{\text{q(1)}}& \qw&\gate{\text{Y}} \qw&\qw\\
+ &\lstick{\text{q(2)}}& \qw&\gate{\text{Z}} \qw&\qw\\
  \\
 }""".strip()
     assert_has_qcircuit_diagram(circuit, expected_diagram)
@@ -148,10 +148,10 @@ def test_two_cx_diagram():
     expected_diagram = r"""
 \Qcircuit @R=1em @C=0.75em {
  \\
- &\lstick{\text{0}}& \qw&\control \qw    &         \qw    &\control \qw    &         \qw    &\qw\\
- &\lstick{\text{1}}& \qw&         \qw\qwx&\control \qw    &         \qw\qwx&\control \qw    &\qw\\
- &\lstick{\text{2}}& \qw&\targ    \qw\qwx&         \qw\qwx&\targ    \qw\qwx&         \qw\qwx&\qw\\
- &\lstick{\text{3}}& \qw&         \qw    &\targ    \qw\qwx&         \qw    &\targ    \qw\qwx&\qw\\
+ &\lstick{\text{q(0)}}& \qw&\control \qw    &         \qw    &\control \qw    &         \qw    &\qw\\
+ &\lstick{\text{q(1)}}& \qw&         \qw\qwx&\control \qw    &         \qw\qwx&\control \qw    &\qw\\
+ &\lstick{\text{q(2)}}& \qw&\targ    \qw\qwx&         \qw\qwx&\targ    \qw\qwx&         \qw\qwx&\qw\\
+ &\lstick{\text{q(3)}}& \qw&         \qw    &\targ    \qw\qwx&         \qw    &\targ    \qw\qwx&\qw\\
  \\
 }""".strip()
     assert_has_qcircuit_diagram(circuit, expected_diagram)
@@ -164,8 +164,8 @@ def test_sqrt_iswap_diagram():
     expected_diagram = r"""
 \Qcircuit @R=1em @C=0.75em {
  \\
- &\lstick{\text{0}}& \qw&\multigate{1}{\text{ISWAP}^{0.5}} \qw&\qw\\
- &\lstick{\text{1}}& \qw&\ghost{\text{ISWAP}^{0.5}}        \qw&\qw\\
+ &\lstick{\text{q(0)}}& \qw&\multigate{1}{\text{ISWAP}^{0.5}} \qw&\qw\\
+ &\lstick{\text{q(1)}}& \qw&\ghost{\text{ISWAP}^{0.5}}        \qw&\qw\\
  \\
 }""".strip()
     assert_has_qcircuit_diagram(circuit, expected_diagram)
diff --git a/cirq-core/cirq/contrib/quantum_volume/quantum_volume_test.py b/cirq-core/cirq/contrib/quantum_volume/quantum_volume_test.py
@@ -97,10 +97,10 @@ def test_sample_heavy_set_with_parity():
     result = cirq.ResultDict(
         params=cirq.ParamResolver({}),
         measurements={
-            '0': np.array([[1], [0]]),
-            '1': np.array([[0], [1]]),
-            '2': np.array([[1], [1]]),
-            '3': np.array([[0], [0]]),
+            'q(0)': np.array([[1], [0]]),
+            'q(1)': np.array([[0], [1]]),
+            'q(2)': np.array([[1], [1]]),
+            'q(3)': np.array([[0], [0]]),
         },
     )
     sampler.run = MagicMock(return_value=result)

diff --git a/cirq-core/cirq/contrib/quimb/mps_simulator_test.py b/cirq-core/cirq/contrib/quimb/mps_simulator_test.py
@@ -214,19 +214,19 @@ def test_measurement_1qubit():
     simulator = ccq.mps_simulator.MPSSimulator()
 
     result = simulator.run(circuit, repetitions=100)
-    assert sum(result.measurements['1'])[0] < 80
-    assert sum(result.measurements['1'])[0] > 20
+    assert sum(result.measurements['q(1)'])[0] < 80
+    assert sum(result.measurements['q(1)'])[0] > 20
 
 
 def test_reset():
     q = cirq.LineQubit(0)
     simulator = ccq.mps_simulator.MPSSimulator()
     c = cirq.Circuit(cirq.X(q), cirq.reset(q), cirq.measure(q))
-    assert simulator.sample(c)['0'][0] == 0
+    assert simulator.sample(c)['q(0)'][0] == 0
     c = cirq.Circuit(cirq.H(q), cirq.reset(q), cirq.measure(q))
-    assert simulator.sample(c)['0'][0] == 0
+    assert simulator.sample(c)['q(0)'][0] == 0
     c = cirq.Circuit(cirq.reset(q), cirq.measure(q))
-    assert simulator.sample(c)['0'][0] == 0
+    assert simulator.sample(c)['q(0)'][0] == 0
 
 
 def test_measurement_2qubits():
@@ -236,7 +236,7 @@ def test_measurement_2qubits():
     simulator = ccq.mps_simulator.MPSSimulator()
 
     repetitions = 1024
-    measurement = simulator.run(circuit, repetitions=repetitions).measurements['0,2']
+    measurement = simulator.run(circuit, repetitions=repetitions).measurements['q(0),q(2)']
 
     result_counts = {'00': 0, '01': 0, '10': 0, '11': 0}
     for i in range(repetitions):
@@ -309,7 +309,7 @@ def test_empty_step_result():
     step_result = next(sim.simulate_moment_steps(cirq.Circuit(cirq.measure(q0))))
     assert (
         str(step_result)
-        == """0=0
+        == """q(0)=0
 TensorNetwork([
     Tensor(shape=(2,), inds=('i_0',), tags=set()),
 ])"""
@@ -322,7 +322,7 @@ def test_step_result_repr_pretty():
     step_result = next(sim.simulate_moment_steps(cirq.Circuit(cirq.measure(q0))))
     cirq.testing.assert_repr_pretty(
         step_result,
-        """0=0
+        """q(0)=0
 TensorNetwork([
     Tensor(shape=(2,), inds=('i_0',), tags=set()),
 ])""",
@@ -441,7 +441,7 @@ def test_run_no_repetitions():
     simulator = ccq.mps_simulator.MPSSimulator()
     circuit = cirq.Circuit(cirq.H(q0), cirq.measure(q0))
     result = simulator.run(circuit, repetitions=0)
-    assert len(result.measurements['0']) == 0
+    assert len(result.measurements['q(0)']) == 0
 
 
 def test_run_parameters_not_resolved():

diff --git a/cirq-core/cirq/contrib/routing/swap_network_test.py b/cirq-core/cirq/contrib/routing/swap_network_test.py
@@ -70,14 +70,15 @@ def test_swap_network_str():
     swap_network = ccr.SwapNetwork(routed_circuit, initial_mapping)
     actual_str = str(swap_network)
     expected_str = """
-(0, 0): ───0───ZZ───0───╲0╱───1────────1─────────1───ZZ───1───╲0╱───3────────3─────────3───ZZ───3───╲0╱───4───
-               │        │                            │        │                            │        │
-(1, 0): ───1───ZZ───1───╱1╲───0───ZZ───0───╲0╱───3───ZZ───3───╱1╲───1───ZZ───1───╲0╱───4───ZZ───4───╱1╲───3───
-                                  │        │                            │        │
-(2, 0): ───2───ZZ───2───╲0╱───3───ZZ───3───╱1╲───0───ZZ───0───╲0╱───4───ZZ───4───╱1╲───1───ZZ───1───╲0╱───2───
-               │        │                            │        │                            │        │
-(3, 0): ───3───ZZ───3───╱1╲───2───ZZ───2───╲0╱───4───ZZ───4───╱1╲───0───ZZ───0───╲0╱───2───ZZ───2───╱1╲───1───
-                                  │        │                            │        │
-(4, 0): ───4────────4─────────4───ZZ───4───╱1╲───2────────2─────────2───ZZ───2───╱1╲───0────────0─────────0───
+(0, 0): ───q(0)───ZZ───q(0)───╲0╱───q(1)────────q(1)─────────q(1)───ZZ───q(1)───╲0╱───q(3)────────q(3)─────────q(3)───ZZ───q(3)───╲0╱───q(4)───
+                  │           │                                     │           │                                     │           │
+(1, 0): ───q(1)───ZZ───q(1)───╱1╲───q(0)───ZZ───q(0)───╲0╱───q(3)───ZZ───q(3)───╱1╲───q(1)───ZZ───q(1)───╲0╱───q(4)───ZZ───q(4)───╱1╲───q(3)───
+                                           │           │                                     │           │
+(2, 0): ───q(2)───ZZ───q(2)───╲0╱───q(3)───ZZ───q(3)───╱1╲───q(0)───ZZ───q(0)───╲0╱───q(4)───ZZ───q(4)───╱1╲───q(1)───ZZ───q(1)───╲0╱───q(2)───
+                  │           │                                     │           │                                     │           │
+(3, 0): ───q(3)───ZZ───q(3)───╱1╲───q(2)───ZZ───q(2)───╲0╱───q(4)───ZZ───q(4)───╱1╲───q(0)───ZZ───q(0)───╲0╱───q(2)───ZZ───q(2)───╱1╲───q(1)───
+                                           │           │                                     │           │
+(4, 0): ───q(4)────────q(4)─────────q(4)───ZZ───q(4)───╱1╲───q(2)────────q(2)─────────q(2)───ZZ───q(2)───╱1╲───q(0)────────q(0)─────────q(0)───
     """.strip()
+    print(actual_str)
     assert actual_str == expected_str
diff --git a/cirq-core/cirq/devices/grid_qubit.py b/cirq-core/cirq/devices/grid_qubit.py
@@ -254,7 +254,14 @@ def __repr__(self) -> str:
         return f"cirq.GridQid({self.row}, {self.col}, dimension={self.dimension})"
 
     def __str__(self) -> str:
-        return f"({self.row}, {self.col}) (d={self.dimension})"
+        return f"q({self.row}, {self.col}) (d={self.dimension})"
+
+    def _circuit_diagram_info_(
+        self, args: 'cirq.CircuitDiagramInfoArgs'
+    ) -> 'cirq.CircuitDiagramInfo':
+        return protocols.CircuitDiagramInfo(
+            wire_symbols=(f"({self.row}, {self.col}) (d={self.dimension})",)
+        )
 
     def _json_dict_(self) -> Dict[str, Any]:
         return protocols.obj_to_dict_helper(self, ['row', 'col', 'dimension'])
@@ -403,7 +410,12 @@ def __repr__(self) -> str:
         return f"cirq.GridQubit({self.row}, {self.col})"
 
     def __str__(self) -> str:
-        return f"({self.row}, {self.col})"
+        return f"q({self.row}, {self.col})"
+
+    def _circuit_diagram_info_(
+        self, args: 'cirq.CircuitDiagramInfoArgs'
+    ) -> 'cirq.CircuitDiagramInfo':
+        return protocols.CircuitDiagramInfo(wire_symbols=(f"({self.row}, {self.col})",))
 
     def _json_dict_(self) -> Dict[str, Any]:
         return protocols.obj_to_dict_helper(self, ['row', 'col'])

diff --git a/cirq-core/cirq/devices/grid_qubit_test.py b/cirq-core/cirq/devices/grid_qubit_test.py
@@ -53,8 +53,17 @@ def test_pickled_hash():
 
 
 def test_str():
-    assert str(cirq.GridQubit(5, 2)) == '(5, 2)'
-    assert str(cirq.GridQid(5, 2, dimension=3)) == '(5, 2) (d=3)'
+    assert str(cirq.GridQubit(5, 2)) == 'q(5, 2)'
+    assert str(cirq.GridQid(5, 2, dimension=3)) == 'q(5, 2) (d=3)'
+
+
+def test_circuit_info():
+    assert cirq.circuit_diagram_info(cirq.GridQubit(5, 2)) == cirq.CircuitDiagramInfo(
+        wire_symbols=('(5, 2)',)
+    )
+    assert cirq.circuit_diagram_info(cirq.GridQid(5, 2, dimension=3)) == cirq.CircuitDiagramInfo(
+        wire_symbols=('(5, 2) (d=3)',)
+    )
 
 
 def test_repr():

diff --git a/cirq-core/cirq/devices/line_qubit.py b/cirq-core/cirq/devices/line_qubit.py
@@ -190,7 +190,12 @@ def __repr__(self) -> str:
         return f"cirq.LineQid({self.x}, dimension={self.dimension})"
 
     def __str__(self) -> str:
-        return f"{self.x} (d={self.dimension})"
+        return f"q({self.x}) (d={self.dimension})"
+
+    def _circuit_diagram_info_(
+        self, args: 'cirq.CircuitDiagramInfoArgs'
+    ) -> 'cirq.CircuitDiagramInfo':
+        return protocols.CircuitDiagramInfo(wire_symbols=(f"{self.x} (d={self.dimension})",))
 
     def _json_dict_(self) -> Dict[str, Any]:
         return protocols.obj_to_dict_helper(self, ['x', 'dimension'])
@@ -241,7 +246,12 @@ def __repr__(self) -> str:
         return f"cirq.LineQubit({self.x})"
 
     def __str__(self) -> str:
-        return f"{self.x}"
+        return f"q({self.x})"
+
+    def _circuit_diagram_info_(
+        self, args: 'cirq.CircuitDiagramInfoArgs'
+    ) -> 'cirq.CircuitDiagramInfo':
+        return protocols.CircuitDiagramInfo(wire_symbols=(f"{self.x}",))
 
     def _json_dict_(self) -> Dict[str, Any]:
         return protocols.obj_to_dict_helper(self, ['x'])
diff --git a/cirq-core/cirq/devices/line_qubit_test.py b/cirq-core/cirq/devices/line_qubit_test.py
@@ -35,8 +35,8 @@ def test_eq():
 
 
 def test_str():
-    assert str(cirq.LineQubit(5)) == '5'
-    assert str(cirq.LineQid(5, dimension=3)) == '5 (d=3)'
+    assert str(cirq.LineQubit(5)) == 'q(5)'
+    assert str(cirq.LineQid(5, dimension=3)) == 'q(5) (d=3)'
 
 
 def test_repr():

diff --git a/cirq-core/cirq/ion/ion_device_test.py b/cirq-core/cirq/ion/ion_device_test.py
@@ -202,11 +202,11 @@ def test_validate_circuit_repeat_measurement_keys():
 
 
 def test_ion_device_str():
-    assert str(ion_device(3)) == "0───1───2"
+    assert str(ion_device(3)) == "q(0)───q(1)───q(2)"
 
 
 def test_ion_device_pretty_repr():
-    cirq.testing.assert_repr_pretty(ion_device(3), "0───1───2")
+    cirq.testing.assert_repr_pretty(ion_device(3), "q(0)───q(1)───q(2)")
     cirq.testing.assert_repr_pretty(ion_device(3), "IonDevice(...)", cycle=True)
 
 

diff --git a/cirq-core/cirq/neutral_atoms/neutral_atom_devices_test.py b/cirq-core/cirq/neutral_atoms/neutral_atom_devices_test.py
@@ -276,10 +276,10 @@ def test_str():
     assert (
         str(square_device(2, 2)).strip()
         == """
-(0, 0)───(0, 1)
-│        │
-│        │
-(1, 0)───(1, 1)
+q(0, 0)───q(0, 1)
+│         │
+│         │
+q(1, 0)───q(1, 1)
     """.strip()
     )
 
@@ -288,10 +288,10 @@ def test_repr_pretty():
     cirq.testing.assert_repr_pretty(
         square_device(2, 2),
         """
-(0, 0)───(0, 1)
-│        │
-│        │
-(1, 0)───(1, 1)
+q(0, 0)───q(0, 1)
+│         │
+│         │
+q(1, 0)───q(1, 1)
     """.strip(),
     )
     cirq.testing.assert_repr_pretty(square_device(2, 2), "cirq.NeutralAtomDevice(...)", cycle=True)

diff --git a/cirq-core/cirq/ops/classically_controlled_operation_test.py b/cirq-core/cirq/ops/classically_controlled_operation_test.py
@@ -208,7 +208,7 @@ def test_qasm():
 include "qelib1.inc";
 
 
-// Qubits: [0, 1]
+// Qubits: [q(0), q(1)]
 qreg q[2];
 creg m_a[1];
 
@@ -416,7 +416,7 @@ def test_decompose():
 def test_str():
     q0 = cirq.LineQubit(0)
     op = cirq.X(q0).with_classical_controls('a')
-    assert str(op) == 'X(0).with_classical_controls(a)'
+    assert str(op) == 'X(q(0)).with_classical_controls(a)'
 
 
 def test_scope_local():

diff --git a/cirq-core/cirq/ops/controlled_gate_test.py b/cirq-core/cirq/ops/controlled_gate_test.py
@@ -514,11 +514,11 @@ def test_circuit_diagram():
     cirq.testing.assert_has_diagram(
         c,
         """
-0: ───@──────
+0: ───@─────────
       │
-1: ───H(1)───
+1: ───H(q(1))───
       │
-2: ───H(2)───
+2: ───H(q(2))───
 """,
     )
 
@@ -530,13 +530,13 @@ def test_circuit_diagram():
     cirq.testing.assert_has_diagram(
         c,
         """
-0 (d=3): ───@────────────
+0 (d=3): ───@───────────────
             │
-1 (d=3): ───(0,1)────────
+1 (d=3): ───(0,1)───────────
             │
-2 (d=3): ───(0,2)────────
+2 (d=3): ───(0,2)───────────
             │
-3 (d=2): ───H(3 (d=2))───
+3 (d=2): ───H(q(3) (d=2))───
 """,
     )