Add layer fidelity experiment

qiskit_experiments/library/randomized_benchmarking/__init__.py

@@ -25,6 +25,7 @@
 
     StandardRB
     InterleavedRB
+    LayerFidelity
 
 
 Analysis
@@ -36,6 +37,7 @@
 
     RBAnalysis
     InterleavedRBAnalysis
+    LayerFidelityAnalysis
 
 Synthesis
 =========
@@ -61,3 +63,5 @@
 from .clifford_utils import CliffordUtils
 from .rb_utils import RBUtils
 from .clifford_synthesis import RBDefaultCliffordSynthesis
+from .layer_fidelity import LayerFidelity
+from .layer_fidelity_analysis import LayerFidelityAnalysis

qiskit_experiments/library/randomized_benchmarking/clifford_utils.py

@@ -486,7 +486,11 @@ def inverse_1q(num: Integral) -> Integral:
 
 
 def num_from_1q_circuit(qc: QuantumCircuit) -> Integral:
-    """Convert a given 1-qubit Clifford circuit to the corresponding integer."""
+    """Convert a given 1-qubit Clifford circuit to the corresponding integer.
+
+    Note: The circuit must consist of gates in :const:`_CLIFF_SINGLE_GATE_MAP_1Q`,
+    RZGate, Delay and Barrier.
+    """
     num = 0
     for inst in qc:
         rhs = _num_from_1q_gate(op=inst.operation)
@@ -497,7 +501,7 @@ def num_from_1q_circuit(qc: QuantumCircuit) -> Integral:
 def _num_from_1q_gate(op: Instruction) -> int:
     """
     Convert a given 1-qubit clifford operation to the corresponding integer.
-    Note that supported operations are limited to ones in :const:`CLIFF_SINGLE_GATE_MAP_1Q` or Rz gate.
+    Note that supported operations are limited to ones in :const:`_CLIFF_SINGLE_GATE_MAP_1Q` or Rz gate.
 
     Args:
         op: operation to be converted.
@@ -556,7 +560,11 @@ def inverse_2q(num: Integral) -> Integral:
 
 
 def num_from_2q_circuit(qc: QuantumCircuit) -> Integral:
-    """Convert a given 2-qubit Clifford circuit to the corresponding integer."""
+    """Convert a given 2-qubit Clifford circuit to the corresponding integer.
+
+    Note: The circuit must consist of gates in :const:`_CLIFF_SINGLE_GATE_MAP_2Q`,
+    RZGate, Delay and Barrier.
+    """
     lhs = 0
     for rhs in _clifford_2q_nums_from_2q_circuit(qc):
         lhs = _CLIFFORD_COMPOSE_2Q_DENSE[lhs, _clifford_num_to_dense_index[rhs]]
@@ -568,7 +576,7 @@ def _num_from_2q_gate(
 ) -> int:
     """
     Convert a given 1-qubit clifford operation to the corresponding integer.
-    Note that supported operations are limited to ones in `CLIFF_SINGLE_GATE_MAP_2Q` or Rz gate.
+    Note that supported operations are limited to ones in `_CLIFF_SINGLE_GATE_MAP_2Q` or Rz gate.
 
     Args:
         op: operation of instruction to be converted.
@@ -730,3 +738,14 @@ def _layer_indices_from_num(num: Integral) -> Tuple[Integral, Integral, Integral
     idx1 = num % _NUM_LAYER_1
     idx0 = num // _NUM_LAYER_1
     return idx0, idx1, idx2
+
+
+@lru_cache(maxsize=24 * 24)
+def _product_1q_nums(first: Integral, second: Integral) -> Integral:
+    """Return the 2-qubit Clifford integer that represents the product of 1-qubit Cliffords."""
+    qc0 = CliffordUtils.clifford_1_qubit_circuit(first)
+    qc1 = CliffordUtils.clifford_1_qubit_circuit(second)
+    qc = QuantumCircuit(2)
+    qc.compose(qc0, qubits=(0,), inplace=True)
+    qc.compose(qc1, qubits=(1,), inplace=True)
+    return num_from_2q_circuit(qc)