diff --git a/quantum/half_adder.py b/quantum/half_adder.py new file mode 100755 index 000000000..1310edbbf --- /dev/null +++ b/quantum/half_adder.py @@ -0,0 +1,59 @@ +#!/usr/bin/env python3 +""" +Build a half-adder quantum circuit that takes two bits as input, +encodes them into qubits, then runs the half-adder circuit calculating +the sum and carry qubits, observed over 1000 runs of the experiment +. + +References: +- https://en.wikipedia.org/wiki/Adder_(electronics) +- https://qiskit.org/textbook/ch-states/atoms-computation.html#4.2-Remembering-how-to-add- +""" + +import qiskit as q + + +def half_adder(bit0: int, bit1: int) -> q.result.counts.Counts: + """ + >>> half_adder(0, 0) + {'00': 1000} + >>> half_adder(0, 1) + {'01': 1000} + >>> half_adder(1, 0) + {'01': 1000} + >>> half_adder(1, 1) + {'10': 1000} + """ + # Use Aer's qasm_simulator + simulator = q.Aer.get_backend("qasm_simulator") + + qc_ha = q.QuantumCircuit(4, 2) + # encode inputs in qubits 0 and 1 + if bit0 == 1: + qc_ha.x(0) + if bit1 == 1: + qc_ha.x(1) + qc_ha.barrier() + + # use cnots to write XOR of the inputs on qubit2 + qc_ha.cx(0, 2) + qc_ha.cx(1, 2) + + # use ccx / toffoli gate to write AND of the inputs on qubit3 + qc_ha.ccx(0, 1, 3) + qc_ha.barrier() + + # extract outputs + qc_ha.measure(2, 0) # extract XOR value + qc_ha.measure(3, 1) # extract AND value + + # Execute the circuit on the qasm simulator + job = q.execute(qc_ha, simulator, shots=1000) + + # Return the histogram data of the results of the experiment. + return job.result().get_counts(qc_ha) + + +if __name__ == "__main__": + counts = half_adder(1, 1) + print(f"Half Adder Output Qubit Counts: {counts}")