|
12 | 12 |
|
13 | 13 | from __future__ import annotations |
14 | 14 |
|
15 | | -from typing import List, Tuple |
16 | | - |
17 | 15 | from qiskit.circuit import QuantumCircuit |
18 | | -from qiskit.providers.backend import Backend |
19 | | -from qiskit.qasm import pi |
20 | | - |
21 | | -import numpy as np |
| 16 | +from qiskit.converters import circuit_to_dag |
| 17 | +from qiskit.transpiler import Target |
| 18 | +from qiskit.transpiler.passes.layout.vf2_utils import ( |
| 19 | + build_average_error_map, |
| 20 | + build_interaction_graph, |
| 21 | + score_layout, |
| 22 | +) |
22 | 23 |
|
23 | 24 |
|
24 | | -def cost_func_scaled_cr( |
25 | | - circ: QuantumCircuit, |
26 | | - layouts: List[List[int]], |
27 | | - backend: Backend, |
28 | | -) -> List[Tuple[List[int], float]]: |
29 | | - """ |
30 | | - A custom cost function that includes T1 and T2 computed during idle periods, |
31 | | - for an already transpiled and scheduled circuit circ |
| 25 | +def avg_error_score(qc_isa: QuantumCircuit, target: Target) -> float: |
| 26 | + """Calculate average error score using vf2 utils |
32 | 27 |
|
33 | | - Parameters: |
34 | | - circ (QuantumCircuit): scheduled circuit of interest |
35 | | - backend (IBMQBackend): An IBM Quantum backend instance |
| 28 | + Args: |
| 29 | + qc_isa (QuantumCircuit): transpiled circuit |
| 30 | + target (Target): backend target |
36 | 31 |
|
37 | 32 | Returns: |
38 | | - float: error |
| 33 | + float: average error score determined by average error map |
39 | 34 | """ |
40 | | - out = [] |
41 | | - props = backend.properties() |
42 | | - inst_sched_map = backend.defaults().instruction_schedule_map |
43 | | - dt = backend.configuration().dt |
44 | | - num_qubits = backend.configuration().num_qubits |
45 | | - t1s = [props.qubit_property(qq, "T1")[0] for qq in range(num_qubits)] |
46 | | - t2s = [props.qubit_property(qq, "T2")[0] for qq in range(num_qubits)] |
47 | | - |
48 | | - error = 0.0 |
49 | | - fid = 1.0 |
50 | | - touched = set() |
51 | | - for layout in layouts: |
52 | | - for item in circ.data: |
53 | | - if item[0].num_qubits == 2: |
54 | | - q0 = circ.find_bit(item[1][0]).index |
55 | | - q1 = circ.find_bit(item[1][1]).index |
56 | | - if inst_sched_map.has("cx", qubits=[q0, q1]): |
57 | | - basis_2q_error = props.gate_error("cx", [q0, q1]) |
58 | | - elif inst_sched_map.has("ecr", qubits=[q0, q1]): |
59 | | - basis_2q_error = props.gate_error("ecr", [q0, q1]) |
60 | | - elif inst_sched_map.has("ecr", qubits=[q1, q0]): |
61 | | - basis_2q_error = props.gate_error("ecr", [q1, q0]) |
62 | | - else: |
63 | | - print( |
64 | | - f"{backend.name} missing 2Q gate between qubit pair ({q0}, {q1})" |
65 | | - ) |
66 | | - |
67 | | - if item[0].name == "cx": |
68 | | - fid *= 1 - basis_2q_error |
69 | | - touched.add(q0) |
70 | | - touched.add(q1) |
71 | | - |
72 | | - # if it is a scaled pulse derived from cx |
73 | | - elif item[0].name == "rzx": |
74 | | - cr_error = np.abs(float(item[0].params[0]) / (pi / 2)) * basis_2q_error |
75 | | - |
76 | | - # assumes control qubit is actually control for cr |
77 | | - echo_error = props.gate_error("x", q0) |
78 | | - |
79 | | - fid *= 1 - max(cr_error, 2 * echo_error) |
80 | | - elif item[0].name == "secr": |
81 | | - cr_error = ( |
82 | | - np.abs((float(item[0].params[0])) / (pi / 2)) * basis_2q_error |
83 | | - ) |
84 | | - |
85 | | - # assumes control qubit is actually control for cr |
86 | | - echo_error = props.gate_error("x", q0) |
87 | | - |
88 | | - fid *= 1 - max(cr_error, echo_error) |
89 | | - |
90 | | - elif item[0].name in ["sx", "x"]: |
91 | | - q0 = circ.find_bit(item[1][0]).index |
92 | | - fid *= 1 - props.gate_error(item[0].name, q0) |
93 | | - touched.add(q0) |
94 | | - |
95 | | - # if it is a dynamical decoupling pulse |
96 | | - elif item[0].name in ["xp", "xm", "y", "yp", "ym"]: |
97 | | - q0 = circ.find_bit(item[1][0]).index |
98 | | - fid *= 1 - props.gate_error("x", q0) |
99 | | - touched.add(q0) |
100 | | - |
101 | | - elif item[0].name == "measure": |
102 | | - q0 = circ.find_bit(item[1][0]).index |
103 | | - fid *= 1 - props.readout_error(q0) |
104 | | - touched.add(q0) |
105 | | - |
106 | | - elif item[0].name == "delay": |
107 | | - q0 = circ.find_bit(item[1][0]).index |
108 | | - # Ignore delays that occur before gates |
109 | | - # This assumes you are in ground state and errors |
110 | | - # do not occur. |
111 | | - if q0 in touched: |
112 | | - time = item[0].duration * dt |
113 | | - fid *= 1 - idle_error(time, t1s[q0], t2s[q0]) |
114 | | - |
115 | | - error = 1 - fid |
116 | | - out.append((layout, error)) |
117 | | - return out |
118 | | - |
119 | | - |
120 | | -def idle_error( |
121 | | - time: float, |
122 | | - t1: float, |
123 | | - t2: float, |
124 | | -) -> float: |
125 | | - """Compute the approx. idle error from T1 and T2 |
126 | | - Parameters: |
127 | | - time (float): Delay time in sec |
128 | | - t1 (float): T1 time in sec |
129 | | - t2, (float): T2 time in sec |
130 | | - Returns: |
131 | | - float: Idle error |
132 | | - """ |
133 | | - t2 = min(t1, t2) |
134 | | - rate1 = 1 / t1 |
135 | | - rate2 = 1 / t2 |
136 | | - p_reset = 1 - np.exp(-time * rate1) |
137 | | - p_z = (1 - p_reset) * (1 - np.exp(-time * (rate2 - rate1))) / 2 |
138 | | - return p_z + p_reset |
139 | | - |
140 | | - |
141 | | -def cost_func_ecr( |
142 | | - circ: QuantumCircuit, |
143 | | - layouts: List[List[int]], |
144 | | - backend: Backend, |
145 | | -) -> List[Tuple[List[int], float]]: |
146 | | - """ |
147 | | - A custom cost function that includes ECR gates in either direction |
148 | | -
|
149 | | - Parameters: |
150 | | - circ (QuantumCircuit): circuit of interest |
151 | | - layouts (list of lists): List of specified layouts |
152 | | - backend (IBMQBackend): An IBM Quantum backend instance |
153 | | -
|
154 | | - Returns: |
155 | | - list: Tuples of layout and cost |
156 | | - """ |
157 | | - out = [] |
158 | | - inst_sched_map = backend.defaults().instruction_schedule_map |
159 | | - props = backend.properties() |
160 | | - for layout in layouts: |
161 | | - error = 0.0 |
162 | | - fid = 1.0 |
163 | | - touched = set() |
164 | | - for item in circ.data: |
165 | | - if item[0].name == "ecr": |
166 | | - q0 = layout[circ.find_bit(item[1][0]).index] |
167 | | - q1 = layout[circ.find_bit(item[1][1]).index] |
168 | | - if inst_sched_map.has("ecr", [q0, q1]): |
169 | | - fid *= 1 - props.gate_error("ecr", [q0, q1]) |
170 | | - elif inst_sched_map.has("ecr", [q1, q0]): |
171 | | - fid *= 1 - props.gate_error("ecr", [q1, q0]) |
172 | | - else: |
173 | | - print( |
174 | | - f"{backend.name} does not support {item[0].name} \ |
175 | | - for qubit pair ({q0}, {q1})" |
176 | | - ) |
177 | | - touched.add(q0) |
178 | | - touched.add(q1) |
179 | | - |
180 | | - elif item[0].name in ["sx", "x"]: |
181 | | - q0 = layout[circ.find_bit(item[1][0]).index] |
182 | | - fid *= 1 - props.gate_error(item[0].name, q0) |
183 | | - touched.add(q0) |
184 | | - |
185 | | - elif item[0].name == "measure": |
186 | | - q0 = layout[circ.find_bit(item[1][0]).index] |
187 | | - fid *= 1 - props.readout_error(q0) |
188 | | - touched.add(q0) |
189 | | - |
190 | | - error = 1 - fid |
191 | | - out.append((layout, error)) |
192 | | - return out |
| 35 | + init_layout = qc_isa.layout.final_index_layout() |
| 36 | + dag = circuit_to_dag(qc_isa) |
| 37 | + |
| 38 | + layout = {idx: init_layout[idx] for idx in range(len(init_layout))} |
| 39 | + avg_error_map = build_average_error_map(target, None, None) |
| 40 | + im_graph, im_graph_node_map, reverse_im_graph_node_map, _ = build_interaction_graph( |
| 41 | + dag, strict_direction=False |
| 42 | + ) |
| 43 | + return score_layout( |
| 44 | + avg_error_map, layout, im_graph_node_map, reverse_im_graph_node_map, im_graph |
| 45 | + ) |
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