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Entanglement is not only the most intriguing feature of quantum mechanics, but also a key resource in quantum information science. The entanglement content of random pure quantum states is almost maximal; such states find applications in…

Quantum Physics · Physics 2009-04-04 Giuliano Benenti

Existing abstract models of quantum computation make reference to circuit elements, much in contrast to their classical counterparts. Circuits, as a model of computation, substantially limit algorithmic expression and obscure high-level…

Quantum Physics · Physics 2023-07-18 Santiago Núñez-Corrales

This note considers Kak's observer-reference model of quantum information, where it is shown that qubits carry information that is sqrt n / ln n times classical information, where n is the number of components in the measurement system, to…

Information Theory · Computer Science 2007-07-13 Gayathre Krishnan

A central problem in quantum computation is to understand which quantum circuits are useful for exponential speed-ups over classical computation. We address this question in the setting of query complexity and show that for almost any…

Quantum Physics · Physics 2013-04-18 Fernando G. S. L. Brandao , Michal Horodecki

Superconducting quantum circuits are typically housed in conducting enclosures in order to control their electromagnetic environment. As devices grow in physical size, the electromagnetic modes of the enclosure come down in frequency and…

Quantum Physics · Physics 2020-08-26 P. A. Spring , T. Tsunoda , B. Vlastakis , P. J. Leek

We present a quantum variational algorithm based on a novel circuit that generates all permutations that can be spanned by one- and two-qubits permutation gates. The construction of the circuits follows from group-theoretical results, most…

Quantum Physics · Physics 2026-02-11 Dylan Laplace Mermoud , Andrea Simonetto , Sourour Elloumi

The number of measurements necessary to perform the quantum state reconstruction of a system of qubits grows exponentially with the number of constituents, creating a major obstacle for the design of scalable tomographic schemes. We work…

Quantum Physics · Physics 2015-06-23 U. Seyfarth , L. L. Sanchez-Soto , G. Leuchs

In order to realize a Quantum CPU some schemes for executing fundamental mathematical tasks are needed. In this paper we present some quantum circuits which, using elementary arithmetic operations, allow an approximated calculation of…

Quantum Physics · Physics 2007-05-23 G. Florio , D. Picca

We propose a theory of characterizing quantum circuits with qubit functional configurations. Any quantum circuit can be decomposed into alternating sequences of 1-qubit unitary gates and CNOT gates. Each CNOT sequence prepares the current…

Quantum Physics · Physics 2022-05-13 Zixuan Hu , Sabre Kais

The ability to reach a maximally entangled state from a separable one through the use of a two-qubit unitary operator is analyzed for mixed states. This extension from the known case of pure states shows that there are at least two families…

Quantum Physics · Physics 2018-04-06 Zhe Guan , Huan He , Yong-Jian Han , Chuan-Feng Li , Fernando Galve , Guang-Can Guo

Estimating the eigenstate properties of quantum systems is a long-standing, challenging problem for both classical and quantum computing. Existing universal quantum algorithms typically rely on ideal and efficient query models (e.g. time…

Quantum Physics · Physics 2026-01-21 Jinzhao Sun , Pei Zeng , Tom Gur , M. S. Kim

We study a variant of quantum circuit complexity, the binding complexity: Consider a $n$-qubit system divided into two sets of $k_1$, $k_2$ qubits each ($k_1\leq k_2$) and gates within each set are free; what is the least cost of two-qubit…

Quantum Physics · Physics 2022-06-27 Yuxuan Zhang

We define the algorithmic complexity of a quantum state relative to a given precision parameter, and give upper bounds for various examples of states. We also establish a connection between the entanglement of a quantum state and its…

Quantum Physics · Physics 2009-11-11 Caterina Mora , Hans Briegel

Maximally entangled bipartite unitary operators or gates find various applications from quantum information to being building blocks of minimal models of many-body quantum chaos, and have been referred to as "dual unitaries". Dual unitary…

Quantum Physics · Physics 2020-08-19 Suhail Ahmad Rather , S. Aravinda , Arul Lakshminarayan

In an attempt to better leverage superconducting quantum computers, scaling efforts have become the central concern. These efforts have been further exacerbated by the increased complexity of these circuits. The added complexity can…

Quantum Physics · Physics 2024-06-10 Fadi Wassaf

The number of qubits in current quantum computers is a major restriction on their wider application. To address this issue, Ying conceived of using two or more small-capacity quantum computers to produce a larger-capacity quantum computing…

Quantum Physics · Physics 2021-10-29 Kan He , Shusen Liu , Jinchuan Hou

In this study, we explore a form of quantum circuit complexity that extends to open systems. To illustrate our methodology, we focus on a basic model where the projective Hilbert space of states is depicted by the set of orientations in the…

Quantum Physics · Physics 2024-10-07 E. M. F. Curado , S. Faci , J. P. Gazeau , T. Koide , A. C. Maioli , D. Noguera

We consider recent works on the simulation of quantum circuits using the formalism of matrix product states and the formalism of contracting tensor networks. We provide simplified direct proofs of many of these results, extending an…

Quantum Physics · Physics 2007-05-23 Richard Jozsa

Matrix product states provide a natural entanglement basis to represent a quantum register and operate quantum gates on it. This scheme can be materialized to simulate a quantum adiabatic algorithm solving hard instances of a NP-Complete…

Quantum Physics · Physics 2009-11-11 M. C. Banuls , R. Orus , J. I. Latorre , A. Perez , P. Ruiz-Femenia

The number of qubits used by a quantum algorithm will be a crucial computational resource for the foreseeable future. We show how to obtain the classical query complexity for continuous problems. We then establish a simple formula for a…

Quantum Physics · Physics 2007-05-23 A. Papageorgiou , J. F. Traub