11.6 Searching over two qubits

Go back and look at Figure 11.7. What does this tell you about how many iterations you need for finding one item among four and the probability of your success?

# Set the drawing options
draw_kwargs = {
  "output": "mpl",         # use matplotlib
  "initial_state": True,   # show |0> and 0
  "idle_wires": False,     # don't show unused wires

  "style": {
      "name": "bw",        # black-and-white for book
      "subfontsize": 9,    # font size of subscripts
      "dpi": 600           # image resolution
  }
}

Let’s build the complete circuit to locate |11⟩. We use Qiskit to create a 2-qubit circuit and place the qubits in superposition with two Hadamard H gates.

circuit = QuantumCircuit(2)
circuit.h(0)
circuit.h(1)
circuit.barrier()

<qiskit.circuit.instructionset.InstructionSet...