Tag: QRAM

Today, I am working on the next exercise on the QML track. The goal is to create a QRAM, that entangles phase-information with address bits. A good description of QRAM that I know of, stems from an IBM Quantum hackathon from 2020. The main idea is to encode the addresses, and entangle the address register with the data register via a controlled rotation.

My code …

def prep_address(address):
    bin_address = np.binary_repr(address, width=3)
        
    for i, add_bit in enumerate(bin_address):
        if add_bit == "0":
            qml.PauliX(wires=i)

dev = qml.device("default.qubit", wires=range(4))

@qml.qnode(dev)
def circuit():
    qml.broadcast(qml.Hadamard, range(3), pattern="single")
        
    for i, theta in enumerate(thetas):
        prep_address(i)
        qml.ctrl(op=qml.RY(theta, wires=3), control=range(3))
        prep_address(i)
    return qml.state()

print(qml.draw(circuit)())

Instinctively, I would have reversed the address bit-order, but as long as you keep it consistent, it doesn’t matter. I also didn’t care about saving gates or anything, it’s just important to calculate the addresses correctly.