Driven Discrete Time Quantum Walks
  We introduce the driven discrete time quantum walk, where walkers are added during the walk instead of only at the beginning. This leads to interference in walker number and very different dynamics when compared to the original quantum walk. These dynamics have two regimes, which we illustrate using the one-dimensional line. Then, we explore a search application which has certain advantages over current search protocols, namely that it does not require a complicated initial state nor a specific measurement time to observe the marked state. Finally, we describe a potential experimental implementation using existing technology. 
Craig S. Hamilton and Sonja Barkhofen and Linda Sansoni and Igor Jex   and Christine Silberhorn
quant-ph