One-Way Finite Automata with Quantum and Classical States

  • Shenggen Zheng
  • Daowen Qiu
  • Lvzhou Li
  • Jozef Gruska
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7300)


In this paper, we introduce and explore a new model of quantum finite automata (QFA). Namely, one-way finite automata with quantum and classical states (1QCFA), a one way version of two-way finite automata with quantum and classical states (2QCFA) introduced by Ambainis and Watrous in 2002 [3]. First, we prove that coin-tossing one-way probabilistic finite automata (coin-tossing 1PFA) [23] and one-way quantum finite automata with control language (1QFACL) [6] as well as several other models of QFA, can be simulated by 1QCFA. Afterwards, we explore several closure properties for the family of languages accepted by 1QCFA. Finally, the state complexity of 1QCFA is explored and the main succinctness result is derived. Namely, for any prime m and any ε1 > 0, there exists a language L m that cannot be recognized by any measure-many one-way quantum finite automata (MM-1QFA) [12] with bounded error \(\frac{7}{9}+\epsilon_1\), and any 1PFA recognizing it has at last m states, but L m can be recognized by a 1QCFA for any error bound ε > 0 with O(logm) quantum states and 12 classical states.


Quantum State Bounded Error Classical State Regular Language Finite Automaton 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Shenggen Zheng
    • 1
  • Daowen Qiu
    • 1
    • 3
    • 4
  • Lvzhou Li
    • 1
  • Jozef Gruska
    • 2
  1. 1.Department of Computer ScienceSun Yat-sen UniversityGuangzhouChina
  2. 2.Faculty of InformaticsMasaryk UniversityBrnoCzech Republic
  3. 3.SQIG–Instituto de Telecomunicações, Departamento de Matemática, Instituto Superior TécnicoTULisbonLisbonPortugal
  4. 4.The State Key Laboratory of Computer Science, Institute of SoftwareChinese Academy of SciencesBeijingChina

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