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According to a well-known result in quantum computing, any unitary transformation on a composite system can be generated using $2$-local unitaries. Interestingly, this universality need not hold in the presence of symmetries. In this paper,…

Quantum Physics · Physics 2023-06-12 Sarvagya Jain

We compare predictions of the quantum loop expansion to (essentially) infinite orders with (essentially) exact results in a simple quantum mechanical model.We find that there are exponentially small corrections to the loop expansion, which…

Mathematical Physics · Physics 2012-09-28 Amna Noreen , Kåre Olaussen

Solomonoff's central result on induction is that the posterior of a universal semimeasure M converges rapidly and with probability 1 to the true sequence generating posterior mu, if the latter is computable. Hence, M is eligible as a…

Machine Learning · Computer Science 2007-07-16 Marcus Hutter , Andrej Muchnik

An important result in the theory of quantum control is the "universality" of $2$-local unitary gates, i.e. the fact that any global unitary evolution of a system of $L$ qudits can be implemented by composition of $2$-local unitary gates.…

Quantum Physics · Physics 2026-02-10 Marco Lastres , Frank Pollmann , Sanjay Moudgalya

Suppose we can apply a given 2-qubit Hamiltonian H to any (ordered) pair of qubits. We say H is n-universal if it can be used to approximate any unitary operation on n qubits. While it is well known that almost any 2-qubit Hamiltonian is…

Quantum Physics · Physics 2018-12-20 Andrew M. Childs , Debbie Leung , Laura Mančinska , Maris Ozols

Linear-constraint loops are programs whose transition relation is specified by a system of linear inequalities. The termination problem asks, given a loop, whether it admits an infinite computation. Decidability of termination remains open…

Logic in Computer Science · Computer Science 2026-05-15 Mishel Carelli

The aim of this paper is to generalize Apollonius' problem. The problem is to construct a circle that is tangent to three given circles in a plane. We find the maximum possible number of solution circles in the case of more than the three…

History and Overview · Mathematics 2017-05-16 Egor Morozov

We consider an old question of Slaman and Steel: whether Turing equivalence is an increasing union of Borel equivalence relations none of which contain a uniformly computable infinite sequence. We show this question is deeply connected to…

Logic · Mathematics 2026-02-17 Adam Day , Andrew Marks

We study the limit computability of finding a global optimum of a continuous function. We give a short proof to show that the problem of checking whether a point is a global minimum is not limit computable. Thereby showing the same for the…

Optimization and Control · Mathematics 2019-09-09 K. Lakshmanan

We formulate a notion of abstract loop equations, and show that their solution is provided by a topological recursion under some assumptions, in particular the result takes a universal form. The Schwinger-Dyson equation of the one and two…

Mathematical Physics · Physics 2016-10-05 Gaëtan Borot , Bertrand Eynard , Nicolas Orantin

A numerical illustration of a universally valid Heisenberg uncertainty relation, which was proposed recently, is presented by using the experimental data on spin-measurements by J. Erhart, et al.[ Nature Phys. {\bf 8}, 185 (2012)]. This…

Quantum Physics · Physics 2013-12-03 Kazuo Fujikawa , Koichiro Umetsu

Understanding invertibility in restricted mis\`ere play has been challenging; in particular, the possibility of non-conjugate inverses posed difficulties. Advances have been made in a few specific universes, but a general theorem was…

Combinatorics · Mathematics 2024-10-10 Alfie Davies , Vishal Yadav

Three recent arguments seek to show that the universal applicability of unitary quantum theory is inconsistent with the assumption that a well-conducted measurement always has a definite physical outcome. In this paper I restate and analyze…

Quantum Physics · Physics 2018-10-17 Richard A. Healey

Solomonoff unified Occam's razor and Epicurus' principle of multiple explanations to one elegant, formal, universal theory of inductive inference, which initiated the field of algorithmic information theory. His central result is that the…

Machine Learning · Computer Science 2008-06-26 Marcus Hutter

Nearly linear recurrences are a generalisation of linear recurrences and are instances of linear time-invariant systems in control theory and linear constraint loops in program analysis. In this paper we formulate the Positivity Problem for…

Dynamical Systems · Mathematics 2026-03-04 Amaury Pouly , Mahsa Shirmohammadi , James Worrell

Turing machines and spin models share a notion of universality according to which some simulate all others. Is there a theory of universality that captures this notion? We set up a categorical framework for universality which includes as…

Computational Complexity · Computer Science 2024-09-04 Tomáš Gonda , Tobias Reinhart , Sebastian Stengele , Gemma De les Coves

We prove a number of results motivated by global questions of uniformity in computability theory, and universality of countable Borel equivalence relations. Our main technical tool is a game for constructing functions on free products of…

Logic · Mathematics 2020-01-20 Andrew S Marks

A problem of universality in simulation of evolution of quantum system and in theory of quantum computations is related with the possibility of expression or approximation of arbitrary unitary transformation by composition of specific…

Quantum Physics · Physics 2009-11-06 Alexander Yu. Vlasov

A universal Turing machine is a powerful concept - a single device can compute any function that is computable. A universal spin model, similarly, is a class of physical systems whose low energy behavior simulates that of any spin system.…

Computational Complexity · Computer Science 2024-06-25 Tomáš Gonda , Gemma De les Coves

In this article, we study disjoint universality for certain sequences of operators, that are connected with the differential operator. Actually, the motivation to study such sequences comes from Universal Taylor series, if you change the…

Complex Variables · Mathematics 2020-02-20 Vagia Vlachou