GHZ vs W States: Entanglement Robustness Under Particle Loss

Both the GHZ state and the W state are "maximally" multipartite entangled N-qubit states, but they sit in genuinely different SLOCC entanglement classes with opposite behaviour under loss: tracing out any subset of qubits from a GHZ state leaves the remaining pair with exactly zero pairwise concurrence for N ≥ 3, while the same operation on a W state leaves a robust concurrence of 2/N that shrinks gracefully rather than collapsing. This simulator renders an N-qubit network (3–8 qubits) in 3D, lets you pick GHZ or W, randomly "lose" qubits at a chosen probability the way a real photonic or trapped-ion link would drop particles, and redraws the surviving entangled bonds with brightness proportional to the real closed-form concurrence — with live numeric readouts for surviving qubit count, pairwise concurrence, and whether the full N-party coherence is still intact.