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This paper is a continuation of a previous study on the so-called measure once finite quantum automata model introduced by Moore and Crutchfield in 2000. We investigate conditions assuring that, given a language recognized by such a device…

Formal Languages and Automata Theory · Computer Science 2025-07-16 Andrea Benso , Flavio D'Alessandro , Paolo Papi

Classical programming languages cannot model essential elements of complex systems such as true random number generation. This paper develops a formal programming language called the lambda-q calculus that addresses the fundamental…

Quantum Physics · Physics 2007-05-23 Philip Maymin

We introduce global one-counter tree automata (GOCTA) which deviate from usual counter tree automata by working on only one counter which is passed through the tree in lexicographical order, rather than duplicating the counter at every…

Formal Languages and Automata Theory · Computer Science 2024-06-24 Luisa Herrmann , Richard Mörbitz

We explore bounds of {\em time-space tradeoffs} in language recognition on {\em two-way finite automata} for some special languages. We prove: (1) a time-space tradeoff upper bound for recognition of the languages $L_{EQ}(n)$ on {\em…

Quantum Physics · Physics 2016-03-22 Shenggen Zheng , Daowen Qiu , Jozef Gruska

In this paper, we present a much simpler, direct and elegant approach to the equivalence problem of {\it measure many one-way quantum finite automata} (MM-1QFAs). The approach is essentially generalized from the work of Carlyle [J. Math.…

Computational Complexity · Computer Science 2023-06-19 Tianrong Lin

An enduring challenge in computer science is reducing the runtime required to solve computational problems. Quantum computing has attracted significant attention due to its potential to deliver asymptotically faster solutions to certain…

Quantum Physics · Physics 2025-03-25 Mischa P. Woods

We introduce 2-way finite automata with quantum and classical states (2qcfa's). This is a variant on the 2-way quantum finite automata (2qfa) model which may be simpler to implement than unrestricted 2qfa's; the internal state of a 2qcfa…

Computational Complexity · Computer Science 2007-05-23 Andris Ambainis , John Watrous

The main purpose of this paper is to show that we can exploit the difference ($l_1$-norm and $l_2$-norm) in the probability calculation between quantum and probabilistic computations to claim the difference in their space efficiencies. It…

Quantum Physics · Physics 2007-05-23 Masami Amano , Kazuo Iwama , Rudy Raymond

In classical computation, a "write-only memory" (WOM) is little more than an oxymoron, and the addition of WOM to a (deterministic or probabilistic) classical computer brings no advantage. We prove that quantum computers that are augmented…

Computational Complexity · Computer Science 2014-01-29 Abuzer Yakaryilmaz , Rusins Freivalds , A. C. Cem Say , Ruben Agadzanyan

A quantum cellular automaton (QCA) is an abstract model consisting of an array of finite-dimensional quantum systems that evolves in discrete time by local unitary operations. Here we propose a simple coarse-graining map, where the spatial…

Quantum Physics · Physics 2021-08-03 Pedro C. S. Costa

Quantitative automata (QAs) extend finite-state automata on infinite words with weighted transitions to specify quantitative system properties. However, their finite weight sets rule out properties like average response time, where response…

Formal Languages and Automata Theory · Computer Science 2026-05-29 Thomas A. Henzinger , Nicolas Mazzocchi , N. Ege Saraç , Harun Yılmaz

Quantum finite automata (QFAs) have been extensively studied in the literature. In this paper, we define and systematically study quantum B\"uchi automata (QBAs) over infinite words to model the long-term behavior of quantum systems, which…

Logic in Computer Science · Computer Science 2024-07-29 Qisheng Wang , Mingsheng Ying

1-way quantum finite automata are deterministic and reversible in nature, which greatly reduces its accepting property. In fact the set of languages accepted by 1-way quantum finite automata is a proper subset of regular languages. In this…

Formal Languages and Automata Theory · Computer Science 2015-12-10 Kingshuk Chatterjee , Kumar Sankar Ray

A method of quantization of classical soliton cellular automata (QSCA) is put forward that provides a description of their time evolution operator by means of quantum circuits that involve quantum gates from which the associated Hamiltonian…

Quantum Physics · Physics 2015-06-26 Demosthenes Ellinas , Elena P. Papadopoulou , Yiannis G. Saridakis

One of the properties of Kondacs-Watrous model of quantum finite automata (QFA) is that the probability of the correct answer for a QFA cannot be amplified arbitrarily. In this paper, we determine the maximum probabilities achieved by QFAs…

Quantum Physics · Physics 2007-05-23 Andris Ambainis , Arnolds Kikusts

Quantum algorithms are able to solve particular problems exponentially faster than conventional algorithms, when implemented on a quantum computer. However, all demonstrations to date have required already knowing the answer to construct…

Quantum Physics · Physics 2013-03-22 Xiao-Qi Zhou , Pruet Kalasuwan , Timothy C. Ralph , Jeremy L. O'Brien

Let $L_{>\lambda}(\mathcal{A})$ and $L_{\geq\lambda}(\mathcal{A})$ be the languages recognized by {\em measure many 1-way quantum finite automata (MM-QFA)} (or,{\em enhanced 1-way quantum finite automata(EQFA)}) $\mathcal{A}$ with strict…

Formal Languages and Automata Theory · Computer Science 2023-06-06 Tianrong Lin

We prove that language equivalence of deterministic one-counter automata is NL-complete. This improves the superpolynomial time complexity upper bound shown by Valiant and Paterson in 1975. Our main contribution is to prove that two…

Formal Languages and Automata Theory · Computer Science 2013-01-11 Stanislav Böhm , Stefan Göller , Petr Jančar

First quantum computers very recently have demonstrated "quantum supremacy" or "quantum advantage": Executing a computation that would have been impossible on a classical machine. Today's quantum computers follow the NISQ paradigm: They…

Quantum Physics · Physics 2023-01-30 Sebastian Brandhofer , Simon Devitt , Thomas Wellens , Ilia Polian

One-time programs, computer programs which self-destruct after being run only once, are a powerful building block in cryptography and would allow for new forms of secure software distribution. However, ideal one-time programs have been…

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