A Pair Of Quanta Cannot Be Wed
  Wooters, Zurek and others have shown that "A Single Quantum Cannot Be Cloned". The reason is two-fold: 1. A quantum cloner would permit FTL signaling; 2. A quantum cloner would violate the linearity requirement for quantum superposition. I present here a similar proof that two arbitrary quantum states cannot be universally welded together to produce a double quantum state. In particular, opposite polarization states cannot be perfectly merged. This paper closes another FTL loophole and discloses a new law of nature: Perfect quantum weddings are not possible. 
Nick Herbert