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Entanglement has evolved from an enigmatic concept of quantum physics to a key ingredient of quantum technology. It explains correlations between measurement outcomes that contradict classical physics, and has been widely explored with…

Quantum Physics · Physics 2024-06-05 Philip Thomas , Leonardo Ruscio , Olivier Morin , Gerhard Rempe

We experimentally demonstrate the first quantum system entangled in every degree of freedom (hyperentangled). Using pairs of photons produced in spontaneous parametric downconversion, we verify entanglement by observing a Bell-type…

Quantum Physics · Physics 2009-05-15 Julio T. Barreiro , Nathan K. Langford , Nicholas A. Peters , Paul G. Kwiat

We present Quantum Cloning Machines (QCM) that transform N identical qubits into $M>N$ identical copies and we prove that the fidelity (quality) of these copies is optimal. The connection between cloning and measurement is discussed in…

Quantum Physics · Physics 2009-01-23 N. Gisin , S. Massar

Quantum gates are the building blocks of quantum circuits, which in turn are the cornerstones of quantum information processing. In this work, we theoretically investigate a single-step implementation of both a universal two- (CNOT) and…

Quantum Physics · Physics 2024-07-01 Luiz O. R. Solak , Daniel Z. Rossatto , Celso J. Villas-Boas

In recent years, there has been heightened interest in quantum teleportation, which allows for the transfer of unknown quantum states over arbitrary distances. Quantum teleportation not only serves as an essential ingredient in…

Universal logic gates for two quantum bits (qubits) form an essential ingredient of quantum information processing. However, the photons, one of the best candidates for qubits, suffer from the lack of strong nonlinear coupling required for…

Quantum Physics · Physics 2009-11-10 Zhi Zhao , An-Ning Zhang , Yu-Ao Chen , Han Zhang , Jiangfeng Du , Tao Yang , Jian-Wei Pan

It is shown that quantum devices based only on oscillators cannot serve as the universal quantum computer, despite of entanglement in such devices, which we roughly estimate for the ideal case and for the harmful entanglement with photonic…

General Physics · Physics 2012-09-18 Yuri I. Ozhigov

Entanglement is a counterintuitive feature of quantum physics that is at the heart of quantum technology. High-dimensional quantum states offer unique advantages in various quantum information tasks. Integrated photonic chips have recently…

A scheme is proposed here to achieve swapping and entangling of photonic and atomic qubits with high fidelity. The mechanism is based on the scattering of a single photon from a $\Lambda$-type three-level atom. The evolution of the coupled…

Quantum Physics · Physics 2007-05-23 T. W. Chen , C. K. Law , P. T. Leung

The circuit model of a quantum computer consists of sequences of gate operations between quantum bits (qubits), drawn from a universal family of discrete operations. The ability to execute parallel entangling quantum gates offers clear…

Quantum Physics · Physics 2021-11-19 C. Figgatt , A. Ostrander , N. M. Linke , K. A. Landsman , D. Zhu , D. Maslov , C. Monroe

Quantum networks and distributed quantum computers rely on entanglement generation between photons and long-lived quantum memories. For large-scale architectures, one of the most crucial parameters is the efficiency at which entanglement…

Quantum Physics · Physics 2024-08-06 Javid Javadzade , Majid Zahedian , Florian Kaiser , Vadim Vorobyov , Jörg Wrachtrup

The manipulation of quantum entanglement has found enormous potential for improving performances of devices such as gyroscopes, clocks, and even computers. Similar improvements have been demonstrated for lithography and microscopy. We…

Quantum Physics · Physics 2007-05-23 Hwang Lee , Pieter Kok , Jonathan P. Dowling

Entanglement enables many promising applications in quantum technology. Devising new generation methods and harnessing entanglement are prerequisites for practical applications. Here we realize a distinct polarization-entangled source by…

Quantum Physics · Physics 2024-02-29 Ming-Yuan Gao , Yin-Hai Li , Zhao-Qi-Zhi Han , Qiang Zhou , Guang-Can Guo , Zhi-Yuan Zhou , Bao-Sen Shi

We propose a quantum cloning machine, which clones a qubit into two clones assuming known modulus of expectation value of Pauli Z-matrix. The process is referred to as the mirror phase-covariant cloning, for which the input state is a…

Quantum Physics · Physics 2009-09-10 Karol Bartkiewicz , Adam Miranowicz , Şahin Kaya Özdemir

Quantum network has significant applications both practically and fundamentally. A hybrid architecture with photons and stationary nodes is highly promising. So far, experimental realizations are limited to two nodes with two photons. Going…

We realize the probabilistic cloning and identifying linear independent quantum states of multi-particles system, given prior probability, with universal quantum logic gates using the method of unitary representation. Our result is…

Quantum Physics · Physics 2007-05-23 Chuan-Wei Zhang , Chuan-Feng Li , Guang-Can Guo

Entanglement is a key ingredient for quantum technologies and a fundamental signature of quantumness in a broad range of phenomena encompassing many-body physics, thermodynamics, cosmology, and life sciences. For arbitrary multiparticle…

Quantum Physics · Physics 2016-10-24 Marco Cianciaruso , Thomas R. Bromley , Gerardo Adesso

An arbitrary lossless transformation in high-dimensional quantum space can be decomposed into elementary operations which are easy to implement, and an effective decomposition algorithm is important for constructing high-dimensional…

Quantum Physics · Physics 2022-12-07 Dong-Xu Chen , Junliang Jia , Pei Zhang , Chui-Ping Yang

What interactions are sufficient to simulate arbitrary quantum dynamics in a composite quantum system? We provide an efficient algorithm to simulate any desired two-body Hamiltonian evolution using any fixed two-body entangling n-qubit…

Quantum Physics · Physics 2009-11-07 Jennifer L. Dodd , Michael A. Nielsen , Michael J. Bremner , Robert T. Thew

Gate model quantum computers promise to solve currently intractable computational problems if they can be operated at scale with long coherence times and high fidelity logic. Neutral atom hyperfine qubits provide inherent scalability due to…