berstein-vazirani algorithm

Author: mrtkp9993

Bernstein-Vazirani Algorithm.py

@@ -0,0 +1,55 @@
+'''
+    Bernstein-Vazirani Algorithm
+
+    We know that an oracle function f is implemented like this
+
+    f : {0, 1}^n -> {0, 1}
+
+    f(x) = a x
+
+    Task: Find a.
+
+'''
+from qiskit import IBMQ, BasicAer
+from qiskit import QuantumCircuit, ClassicalRegister, QuantumRegister, execute
+
+qr = QuantumRegister(4)  # Initialize qubits
+cr = ClassicalRegister(4)  # Initialize bits for record measurements
+circuit = QuantumCircuit(qr, cr)
+
+circuit.x(qr[3])  # initialize the ancilla qubit in the |1> state
+
+# First step of quantum algorithms - Prepare the superposition
+# For superposition, we apply the Hadamard gate on all qubits
+circuit.h(qr[0])
+circuit.h(qr[1])
+circuit.h(qr[2])
+circuit.h(qr[3])
+
+# Oracle function
+circuit.cx(qr[0], qr[3])
+circuit.cx(qr[1], qr[3])
+circuit.cx(qr[2], qr[3])
+
+# Apply Hadamard gates after querying oracle function
+circuit.h(qr[0])
+circuit.h(qr[1])
+circuit.h(qr[2])
+circuit.h(qr[3])
+
+# Measure qubit
+circuit.measure(qr[0], cr[0])
+circuit.measure(qr[1], cr[1])
+circuit.measure(qr[2], cr[2])
+
+# Run our circuit with local simulator
+backend = BasicAer.get_backend('qasm_simulator')
+shots = 1024
+results = execute(circuit, backend=backend, shots=shots).result()
+answer = results.get_counts()
+print("Simulator result")
+for c2c1c0 in answer:
+    print(f"{c2c1c0} is observed in {answer[c2c1c0]} times")
+# 0111 observed in 1024 times
+# 0111 in base 2 = 7 in base 10
+# hence, a = 7

README.md

@@ -9,4 +9,8 @@ Quantum computing examples with Qiskit.
 
 **Deutsch-Jozsa Algorithm**
 
-![Deutsch-Jozsa Algorithm](./circuit_diagrams/02_deutsch_jozsa.png)
+![Deutsch-Jozsa Algorithm](./circuit_diagrams/02_deutsch_jozsa.png)
+
+**Bernstein-Vazirani Algorithm**
+
+![Bernstein-Vazirani Algorithm](./circuit_diagrams/03_bernstein_vazirani.png)