lint fixes

Author: rochisha0

src/qutip_qip/algorithms/error_correction/bit_flip.py

@@ -7,10 +7,11 @@
 
 __all__ = ["BitFlipCode"]
 
+
 class BitFlipCode:
     """
     Implementation of the 3-qubit bit-flip code.
-    
+
     The bit-flip code protects against X (bit-flip) errors by encoding
     a single logical qubit across three physical qubits:
     |0⟩ → |000⟩
@@ -21,7 +22,7 @@ class BitFlipCode:
     def encode_circuit():
         """
         Create a circuit for encoding a single qubit into the 3-qubit bit-flip code.
-        
+
         Returns
         -------
         qc : instance of QubitCircuit
@@ -31,53 +32,53 @@ def encode_circuit():
         qc.add_gate("CNOT", controls=0, targets=1)
         qc.add_gate("CNOT", controls=0, targets=2)
         return qc
-    
+
     @staticmethod
     def syndrome_measurement_circuit():
         """
         Create a circuit for syndrome measurement of the 3-qubit bit-flip code.
-        
+
         Returns
         -------
         qc : instance of QubitCircuit
             Syndrome measurement circuit that uses two ancilla qubits.
         """
         qc = QubitCircuit(5)  # 3 data qubits + 2 syndrome qubits
-        
+
         # First syndrome measurement: Parity of qubits 0 and 1
         qc.add_gate("CNOT", controls=0, targets=3)
         qc.add_gate("CNOT", controls=1, targets=3)
-        
+
         # Second syndrome measurement: Parity of qubits 1 and 2
         qc.add_gate("CNOT", controls=1, targets=4)
         qc.add_gate("CNOT", controls=2, targets=4)
-        
+
         return qc
-    
+
     @staticmethod
     def correction_circuit(syndrome):
         """
         Create a circuit for error correction based on syndrome measurement.
-        
+
         Parameters
         ----------
         syndrome : tuple
             Two-bit syndrome measurement result (s1, s2).
-            
+
         Returns
         -------
         qc : instance of QubitCircuit
             Correction circuit applying X gates as needed.
         """
         qc = QubitCircuit(3)
         s1, s2 = syndrome
-        
+
         # Syndrome interpretation:
         # s1=0, s2=0: No error
         # s1=1, s2=0: Error on qubit 0
         # s1=1, s2=1: Error on qubit 1
         # s1=0, s2=1: Error on qubit 2
-        
+
         if s1 == 1 and s2 == 0:
             # Error on qubit 0
             qc.add_gate("X", targets=0)
@@ -87,14 +88,14 @@ def correction_circuit(syndrome):
         elif s1 == 0 and s2 == 1:
             # Error on qubit 2
             qc.add_gate("X", targets=2)
-            
+
         return qc
-    
+
     @staticmethod
     def decode_circuit():
         """
         Create a circuit for decoding the 3-qubit bit-flip code.
-        
+
         Returns
         -------
         qc : instance of QubitCircuit
@@ -103,10 +104,9 @@ def decode_circuit():
         qc = QubitCircuit(3)
         qc.add_gate("CNOT", controls=0, targets=2)
         qc.add_gate("CNOT", controls=0, targets=1)
-        
+
         # Add a Toffoli gate to verify the parity
         # If all qubits have the same value, the result is stored in qubit 0
         qc.add_gate("TOFFOLI", controls=[1, 2], targets=0)
-        
+
         return qc
-    

src/qutip_qip/algorithms/error_correction/phase_flip.py

@@ -5,126 +5,127 @@
 
 __all__ = ["PhaseFlipCode"]
 
+
 class PhaseFlipCode:
     """
     Implementation of the 3-qubit phase-flip code.
     The phase-flip code protects against Z (phase-flip) errors by encoding
     a single logical qubit across three physical qubits:
     |0⟩ → |+++⟩
     |1⟩ → |---⟩
-    
+
     This is accomplished by applying Hadamard gates to transform the bit-flip code
     into the phase-flip code, as phase errors in the Hadamard basis appear as bit-flips.
     """
-    
+
     @staticmethod
     def encode_circuit():
         """
         Create a circuit for encoding a single qubit into the 3-qubit phase-flip code.
-        
+
         Returns
         -------
         qc : instance of QubitCircuit
             Encoding circuit for the phase-flip code.
         """
         qc = QubitCircuit(3)
-        
+
         # First apply Hadamard to the input qubit
         qc.add_gate("SNOT", targets=0)
-        
+
         # Then use the bit-flip encoding structure
         qc.add_gate("CNOT", controls=0, targets=1)
         qc.add_gate("CNOT", controls=0, targets=2)
-        
+
         # Apply Hadamard gates to all qubits
         qc.add_gate("SNOT", targets=0)
         qc.add_gate("SNOT", targets=1)
         qc.add_gate("SNOT", targets=2)
-        
+
         return qc
-    
+
     @staticmethod
     def syndrome_measurement_circuit():
         """
         Create a circuit for syndrome measurement of the 3-qubit phase-flip code.
-        
+
         Returns
         -------
         qc : instance of QubitCircuit
             Syndrome measurement circuit that uses two ancilla qubits.
         """
         qc = QubitCircuit(5)  # 3 data qubits + 2 syndrome qubits
-        
+
         qc.add_gate("SNOT", targets=0)
         qc.add_gate("SNOT", targets=1)
         qc.add_gate("SNOT", targets=2)
-        
+
         qc.add_gate("CNOT", controls=0, targets=3)
         qc.add_gate("CNOT", controls=1, targets=3)
-        
+
         qc.add_gate("CNOT", controls=1, targets=4)
         qc.add_gate("CNOT", controls=2, targets=4)
-        
+
         qc.add_gate("SNOT", targets=0)
         qc.add_gate("SNOT", targets=1)
         qc.add_gate("SNOT", targets=2)
-        
+
         return qc
-    
+
     @staticmethod
     def correction_circuit(syndrome):
         """
         Create a circuit for error correction based on syndrome measurement.
-        
+
         Parameters
         ----------
         syndrome : tuple
             Two-bit syndrome measurement result (s1, s2).
-            
+
         Returns
         -------
         qc : instance of QubitCircuit
             Correction circuit applying Z gates as needed.
         """
         qc = QubitCircuit(3)
         s1, s2 = syndrome
-        
+
         # Syndrome interpretation:
         # s1=0, s2=0: No error
         # s1=1, s2=0: Error on qubit 0
         # s1=1, s2=1: Error on qubit 1
         # s1=0, s2=1: Error on qubit 2
-        
+
         if s1 == 1 and s2 == 0:
             qc.add_gate("Z", targets=0)
         elif s1 == 1 and s2 == 1:
             qc.add_gate("Z", targets=1)
         elif s1 == 0 and s2 == 1:
             qc.add_gate("Z", targets=2)
-            
+
         return qc
-    
+
     @staticmethod
     def decode_circuit():
         """
         Create a circuit for decoding the 3-qubit phase-flip code.
-        
+
         Returns
         -------
         qc : instance of QubitCircuit
             Decoding circuit for the phase-flip code.
         """
         qc = QubitCircuit(3)
-        
+
         qc.add_gate("SNOT", targets=0)
         qc.add_gate("SNOT", targets=1)
         qc.add_gate("SNOT", targets=2)
-        
+
         qc.add_gate("CNOT", controls=0, targets=2)
         qc.add_gate("CNOT", controls=0, targets=1)
-        
+
         qc.add_gate("TOFFOLI", controls=[1, 2], targets=0)
-        
+
         qc.add_gate("SNOT", targets=0)
-        
-        return qc
+
+        return qc

src/qutip_qip/algorithms/error_correction/shor_code.py

@@ -5,61 +5,62 @@
 
 __all__ = ["ShorCode"]
 
+
 class ShorCode:
     """
     Implementation of the 9-qubit Shor code.
-    
+
     The Shor code protects against arbitrary single-qubit errors by combining
     the 3-qubit phase-flip code with the 3-qubit bit-flip code.
-    
+
     The logical states are encoded as:
     |0⟩ → (|000⟩ + |111⟩)(|000⟩ + |111⟩)(|000⟩ + |111⟩) / 2√2
     |1⟩ → (|000⟩ - |111⟩)(|000⟩ - |111⟩)(|000⟩ - |111⟩) / 2√2
-    
-    This encoding allows correction of any single-qubit error (bit-flip, phase-flip, 
+
+    This encoding allows correction of any single-qubit error (bit-flip, phase-flip,
     or both) on any of the 9 physical qubits.
     """
-    
+
     @staticmethod
     def encode_circuit():
         """
         Create a circuit for encoding a single qubit into the 9-qubit Shor code.
-        
+
         The encoding process:
         1. Apply phase-flip encoding to the input (creating |+++⟩ or |---⟩)
         2. Apply bit-flip encoding to each of the three qubits
-        
+
         Returns
         -------
         qc : instance of QubitCircuit
             Encoding circuit for the Shor code.
         """
         qc = QubitCircuit(9)
-        
+
         # Step 1: Phase-flip encoding on the first qubit
         # Apply Hadamard to the input qubit
         qc.add_gate("SNOT", targets=0)
-        
+
         # Create the GHZ-like state by using CNOTs
         qc.add_gate("CNOT", controls=0, targets=3)
         qc.add_gate("CNOT", controls=0, targets=6)
-        
-        # Apply Hadamard to all three qubits 
+
+        # Apply Hadamard to all three qubits
         qc.add_gate("SNOT", targets=0)
         qc.add_gate("SNOT", targets=3)
         qc.add_gate("SNOT", targets=6)
-        
+
         # Step 2: Bit-flip encoding for each of the three blocks
         # First block: qubits 0,1,2
         qc.add_gate("CNOT", controls=0, targets=1)
         qc.add_gate("CNOT", controls=0, targets=2)
-        
+
         # Second block: qubits 3,4,5
         qc.add_gate("CNOT", controls=3, targets=4)
         qc.add_gate("CNOT", controls=3, targets=5)
-        
+
         # Third block: qubits 6,7,8
         qc.add_gate("CNOT", controls=6, targets=7)
         qc.add_gate("CNOT", controls=6, targets=8)
-        
-        return qc
+
+        return qc