منابع مشابه
Space-Bounded Quantum Complexity
This paper investigates the computational power of space-bounded quantum Turing machines. The following facts are proved for space-constructible space bounds s satisfying s(n) = Ω(log n). 1. Any quantum Turing machine (QTM) running in space s can be simulated by an unbounded error probabilistic Turing machine (PTM) running in space O(s). No assumptions on the probability of error or running tim...
متن کاملQuantum branching programs and space-bounded nonuniform quantum complexity
In this paper, the space complexity of nonuniform quantum computations is investigated. The model chosen for this are quantum branching programs (QBPs), which provide a graphic description of sequential quantum algorithms. In the first part of the paper, simulations between QBPs and nonuniform quantum Turing machines are presented, which allow to transfer lower and upper bound results between t...
متن کاملRelationships Between Quantum and Classical Space-Bounded Complexity Classes
This paper investigates the relative power of space-bounded quantum and classical (probabilistic) computational models. The following relationships are proved. 1. Any probabilistic Turing machine (PTM) which runs in space s and which halts absolutely (i.e. halts with certainty after a nite number of steps) can be simulated in space O(s) by a quantum Turing machine (QTM). If the PTM operates wit...
متن کاملQuantum Bounded Query Complexity
We combine the classical notions and techniques for bounded query classes with those developed in quantum computing. We give strong evidence that quantum queries to an oracle in the class NP does indeed reduce the query complexity of decision problems. Under traditional complexity assumptions, we obtain an exponential speedup between the quantum and the classical query complexity of function cl...
متن کاملNotes on Space - Bounded Complexity
A machine solves a problem using space s(·) if, for every input x, the machine outputs the correct answer and uses only the first s(|x|) cells of the tape. For a standard Turing machine, we can’t do better than linear space since x itself must be on the tape. So we will often consider a machine with multiple tapes: a read-only “input” tape, a read/write “work” or “memory” tape, and possibly a w...
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ژورنال
عنوان ژورنال: Journal of Computer and System Sciences
سال: 1999
ISSN: 0022-0000
DOI: 10.1006/jcss.1999.1655