Quantum and Stochastic Branching Programs of Bounded Width

Track A
  • Farid Ablayev
  • Cristopher Moore
  • Christopher Pollett
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2380)


We prove upper and lower bounds on the power of quantum and stochastic branching programs of bounded width. We show any NC1 language can be accepted exactly by a width-2 quantum branching program of polynomial length, in contrast to the classical case where width 5 is necessary unless NC1 = ACC. This separates width-2 quantum programs from width-2 doubly stochastic programs as we show the latter cannot compute the middle bit of multiplication. Finally, we show that bounded-width quantum and stochastic programs can be simulated by classical programs of larger but bounded width, and thus are in NC1.


Boolean Function Sink Node Stochastic Program Binary Decision Diagram Stochastic Matrice 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2002

Authors and Affiliations

  • Farid Ablayev
    • 1
  • Cristopher Moore
    • 2
  • Christopher Pollett
    • 3
  1. 1.Dept. of Theoretical CyberneticsKazan State UniversityKazanRussia
  2. 2.Computer Science DepartmentUniversity of New MexicoAlbuquerque
  3. 3.Dept. of Math and Computer ScienceSan Jose State UniversitySan Jose

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