Yes, cloud-based quantum computing can offer a quantum advantage, particularly when quantum circuits capable of generating entangled states are realized. Entangled qubits can significantly speed up certain computations.

Entanglement witness circuits are specially designed circuits that help certify the presence of entangled qubits using measurement statistics. They enable researchers to detect entanglement without needing direct control over qubit allocation in cloud-based services.

In some cloud-based services, like IonQ, researchers do not have the ability to choose which qubits to allocate to their circuits. This limitation can hinder their ability to effectively compute the output of entanglement witness functions.