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Classical branching programs are studied to understand the space complexity of computational problems. Prior to this work, Nakanishi and Ablayev had separately defined two different quantum versions of branching programs that we refer to as…

Quantum Physics · Physics 2023-07-24 Debajyoti Bera , Tharrmashastha Sapv

We present quantum complexity lower and upper bounds for independent set problems in graphs. In particular, we give quantum algorithms for computing a maximal and a maximum independent set in a graph. We present applications of these…

Quantum Physics · Physics 2007-05-23 Sebastian Doern

We discuss models of computing that are beyond classical. The primary motivation is to unearth the cause of nonclassical advantages in computation. Completeness results from computational complexity theory lead to the identification of very…

Quantum Physics · Physics 2011-12-22 Animesh Datta , Anil Shaji

We show that a separation between the class of all problems that can efficiently be solved on a quantum computer and those solvable using probabilistic classical algorithms in polynomial time implies the generalized contextuality of quantum…

Quantum Physics · Physics 2021-12-16 Farid Shahandeh

Quantum machine learning (QML) holds promise for accelerating pattern recognition, optimization, and data analysis, but the conditions under which it can truly outperform classical approaches remain unclear. Existing research often…

Quantum Physics · Physics 2025-09-23 Christophe Pere

In this note we describe a simple and intriguing observation: the quantum Fourier transform (QFT) over $Z_q$, which is considered the most ``quantum'' part of Shor's algorithm, can in fact be simulated efficiently by classical computers.…

Quantum Physics · Physics 2007-05-23 Dorit Aharonov , Zeph Landau , Johann Makowsky

A recent paper on quantum walks by Childs et al. [STOC'03] provides an example of a black-box problem for which there is a quantum algorithm with exponential speedup over the best classical randomized algorithm for the problem, but where…

Quantum Physics · Physics 2007-05-23 Stephen A. Fenner , Yong Zhang

Classical verification of quantum learning allows classical clients to reliably leverage quantum computing advantages by interacting with untrusted quantum servers. Yet, current quantum devices available in practice suffers from a variety…

Quantum Physics · Physics 2024-11-15 Yinghao Ma , Jiaxi Su , Dong-Ling Deng

We consider quantum versions of two well-studied classical learning models: Angluin's model of exact learning from membership queries and Valiant's Probably Approximately Correct (PAC) model of learning from random examples. We give…

Quantum Physics · Physics 2007-05-23 Rocco A. Servedio , Steven J. Gortler

The so-called welded tree problem provides an example of a black-box problem that can be solved exponentially faster by a quantum walk than by any classical algorithm. Given the name of a special ENTRANCE vertex, a quantum walk can find…

Quantum Physics · Physics 2023-02-02 Andrew M. Childs , Matthew Coudron , Amin Shiraz Gilani

It is not known what the limitations are on using quantum computation to speed up classical computation. An example would be the power to speed up PSPACE-complete computations. It is also not known what the limitations are on the duration…

High Energy Physics - Theory · Physics 2018-02-08 Leonard Susskind

Quantum computers are considered as a part of the family of the reversible, lineary-extended, dynamical systems (Quanputers). For classical problems an operational reformulation is given. A universal algorithm for the solving of classical…

Quantum Physics · Physics 2007-05-23 Nugzar Makhaldiani

We define a new model of quantum learning that we call Predictive Quantum (PQ). This is a quantum analogue of PAC, where during the testing phase the student is only required to answer a polynomial number of testing queries. We demonstrate…

Quantum Physics · Physics 2022-03-29 Dmytro Gavinsky

The complexity of quantum computation remains poorly understood. While physicists attempt to find ways to create quantum computers, we still do not have much evidence one way or the other as to how useful these machines will be. The tools…

Quantum Physics · Physics 2007-05-23 Lance Fortnow

Any particular classical system and its quantum version are normally viewed as separate formulations that are strictly distinct. Our goal is to overcome the two separate languages and create a smooth and common procedure that provides a…

Quantum Physics · Physics 2020-10-13 John R. Klauder

While it seems possible that quantum computers may allow for algorithms offering a computational speed-up over classical algorithms for some problems, the issue is poorly understood. We explore this computational speed-up by investigating…

Quantum Physics · Physics 2010-06-09 Alastair A. Abbott , Cristian S. Calude

The Quantum Oracle Classification (QOC) problem is to classify a function, given only quantum black box access, into one of several classes without necessarily determining the entire function. Generally, QOC captures a very wide range of…

Computational Complexity · Computer Science 2015-10-29 Mark Zhandry

We prove that quantum computation is polynomially equivalent to classical probabilistic computation with an oracle for estimating the value of simple sums, quadratically signed weight enumerators. The problem of estimating these sums can be…

Quantum Physics · Physics 2007-05-23 E. Knill , R. Laflamme

Let $A$ be an $s$-sparse Hermitian matrix, $f(x)$ be a univariate function, and $i, j$ be two indices. In this work, we investigate the query complexity of approximating $\bra{i} f(A) \ket{j}$. We show that for any continuous function…

Quantum Physics · Physics 2025-01-20 Ashley Montanaro , Changpeng Shao

We study quantum algorithms that learn properties of a matrix using queries that return its action on an input vector. We show that for various problems, including computing the trace, determinant, or rank of a matrix or solving a linear…

Quantum Physics · Physics 2021-10-19 Andrew M. Childs , Shih-Han Hung , Tongyang Li