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Quantum state filtering is a variant of the unambiguous state discrimination problem: the states are grouped in sets and we want to determine to which particular set a given input state belongs.The simplest case, when the N given states are…

Quantum Physics · Physics 2009-11-11 Janos A. Bergou , Mark Hillery

We demonstrate that, in the case of Shor's algorithm for factoring, highly mixed states will allow efficient quantum computation, indeed factorization can be achieved efficiently with just one initial pure qubit and a supply of initally…

Quantum Physics · Physics 2009-11-07 S. Parker , M. B. Plenio

Nuclear magnetic resonance techniques are used to realize a quantum algorithm experimentally. The algorithm allows a simple NMR quantum computer to determine global properties of an unknown function requiring fewer function ``calls'' than…

Quantum Physics · Physics 2009-10-31 Isaac L. Chuang , Lieven M. K. Vandersypen , Xinlan Zhou , Debbie W. Leung , Seth Lloyd

Quantum entanglement plays an important role in quantum information processes, such as quantum computation and quantum communication. Experiments in laboratories are unquestionably crucial to increase our understanding of quantum systems…

Quantum Physics · Physics 2019-04-03 Xuemei Gu , Lijun Chen , Anton Zeilinger , Mario Krenn

Quantum machine learning aspires to overcome intractability that currently limits its applicability to practical problems. However, quantum machine learning itself is limited by low effective dimensions achievable in state-of-the-art…

Quantum Physics · Physics 2022-01-04 Kunkun Wang , Lei Xiao , Wei Yi , Shi-Ju Ran , Peng Xue

The optimal use of quantum and classical computational techniques together is important to address problems that cannot be easily solved by quantum computations alone. This is the case of the ground state problem for quantum many-body…

Quantum Physics · Physics 2022-05-03 Patrick Huembeli , Giuseppe Carleo , Antonio Mezzacapo

The requirement of performing both single-qubit and two-qubit operations in the implementation of universal quantum logic often leads to very demanding constraints on quantum computer design. We show here how to eliminate the need for…

Quantum Physics · Physics 2016-09-08 D. A. Lidar , L. -A. Wu

In this paper we discuss how we can design Hamiltonians to implement quantum algorithms, in particular we focus in Deutsch and Grover algorithms. As main result of this paper, we show how Hamiltonian inverse quantum engineering method allow…

Quantum Physics · Physics 2018-04-25 Alan C Santos

Systems of linear equations are used to model a wide array of problems in all fields of science and engineering. Recently, it has been shown that quantum computers could solve linear systems exponentially faster than classical computers,…

Quantum entanglement, after playing a significant role in the development of the foundations of quantum mechanics, has been recently rediscovered as a new physical resource with potential commercial applications such as, for example,…

Quantum Physics · Physics 2009-11-07 Pawel Horodecki , Artur Ekert

In addition to being a workhorse for modern quantum technologies, entanglement plays a key role in fundamental tests of quantum mechanics. The entanglement of photons in multiple levels, or dimensions, explores the limits of how large an…

Quantum Physics · Physics 2018-03-12 Manuel Erhard , Mehul Malik , Anton Zeilinger

The operational structure of quantum couplings and entanglements is studied and classified for semifinite von Neumann algebras. We show that the classical-quantum correspondences such as quantum encodings can be treated as diagonal…

Quantum Physics · Physics 2009-11-07 V. P. Belavkin , M. Ohya

We discuss the fundamental role of entanglement as the essential nonclassical feature providing the computational speed-up in the known quantum algorithms. We review the construction of the Fourier transform on an Abelian group and the…

Quantum Physics · Physics 2009-10-31 Artur Ekert , Richard Jozsa

Quantifying the entanglement generation of a multipartite unitary operation is a key problem in quantum information processing. We introduce the definition of multipartite entangling, assisted entangling, and disentangling power, which is a…

Quantum Physics · Physics 2024-10-22 Xinyu Qiu , Zhiwei Song , Lin Chen

A new approach to the classical limit of Grover's algorithm is discussed by assuming a very rapid dephasing of a system between consecutive Grover's unitary operations, which drives pure quantum states to decohered mixed states. One can…

Quantum Physics · Physics 2019-03-27 Kazuo Fujikawa , C. H. Oh , Koichiro Umetsu

Quantum algorithms reformulate computational problems as quantum evolutions in a large Hilbert space. Most quantum algorithms assume that the time-evolution is perfectly unitary and that the full Hilbert space is available. However, in…

Quantum Physics · Physics 2024-09-26 Marcel Niedermeier , Jose L. Lado , Christian Flindt

Quantum parallelism is the main feature of quantum computation. In 1985 D. Deutsch showed that a single quantum computation may be sufficient to state whether a two-valued function of a two-valued variable is constant or not. Though the…

Quantum Physics · Physics 2007-05-23 Giovanni Costantini , Fabrizio Smeraldi

We perform quantum interference experiments on a single self-assembled semiconductor quantum dot. The presence or absence of a single exciton in the dot provides a qubit that we control with femtosecond time resolution. We combine a set of…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 P. Bianucci , A. Muller , C. K. Shih , Q. Q. Wang , X. K. Xue , C. Piermarocchi

We implement a protocol to determine the degree of entanglement between a qubit and the rest of the system on a quantum computer. The protocol is based on results obtained in paper [Frydryszak et al. (2017)]. This protocol is tested on a…

Quantum Physics · Physics 2020-06-24 A. R. Kuzmak , V. M. Tkachuk

Quantum information theory is a rapidly growing area of math and physics that combines two independent theories, quantum mechanics and information theory. Quantum entanglement is a concept that was first proposed in the EPR paradox. In…

Quantum Physics · Physics 2025-11-19 Lane Boswell , Ying Cao