Experimentally generating and tuning robust entanglement between photonic qubits

We generate and study the entanglement properties of novel states composed of three polarisation-encoded photonic qubits. By varying a single experimental parameter we can coherently move from a fully separable state to a maximally robust W state, while at all times preserving an optimally robust, symmetric entanglement configuration. We achieve a high fidelity with these configurations experimentally, including the highest reported W state fidelity.