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The entangled state that results when a detector measures a superposed quantum system has spawned decades of concern about the problem of definite outcomes or "Schrodinger's cat." This state seems to describe a detector in an indefinite or…

Quantum Physics · Physics 2022-06-14 Art Hobson

The ability to transmit quantum states over long distances is a fundamental requirement of the quantum internet and is reliant upon quantum repeaters. Quantum repeaters involve entangled photon sources that emit and deliver photonic…

Our objective was to design a quantum repeater capable of achieving one million entangled pairs per second over a distance of 1000km. We failed, but not by much. In this letter we will describe the series of developments that permitted us…

Quantum Physics · Physics 2015-05-14 W. J. Munro , K. A. Harrison , A. M. Stephens , S. J. Devitt , Kae Nemoto

We introduce a repeater scheme to efficiently distribute multipartite entangled states in a quantum network with optimal scaling. The scheme allows to generate graph states such as 2D and 3D cluster states of growing size or GHZ states over…

Quantum Physics · Physics 2019-01-30 Julius Wallnöfer , Alexander Pirker , Michael Zwerger , Wolfgang Dür

Quantum repeater holds the promise for scalable long-distance quantum communication. Towards a first quantum repeater based on memory-photon entanglement, significant progresses have made in improving performances of the building blocks.…

Quantum Physics · Physics 2016-04-06 Sheng-Jun Yang , Xu-Jie Wang , Xiao-Hui Bao , Jian-Wei Pan

In this paper we study the production of entanglement between two atoms which are far from each other. We consider a system including eight two-level atoms (1; 2;... ; 8) such that any atom with its adjacent atom is in atomic Bell state, so…

Quantum Physics · Physics 2021-06-04 M Ghasemi , M K Tavassoly

Quantum physics allows for entanglement between microscopic and macroscopic objects, described by discrete and continuous variables, respectively. As in Schr\"odinger's famous cat gedanken experiment, a box enclosing the objects can keep…

Quantum Physics · Physics 2019-07-18 Bastian Hacker , Stephan Welte , Severin Daiss , Armin Shaukat , Stephan Ritter , Lin Li , Gerhard Rempe

We show how to create practical, efficient, quantum repeaters, employing double-photon guns, for long-distance optical quantum communication. The guns create polarization-entangled photon pairs on demand. One such source might be a…

Quantum Physics · Physics 2009-11-07 Pieter Kok , Colin P. Williams , Jonathan P. Dowling

The quantum repeater protocol is a promising approach to implement long-distance quantum communication and large-scale quantum networks. A key idea of the quantum repeater protocol is to use long-lived quantum memories to achieve efficient…

Quantum Physics · Physics 2022-01-31 Yunfei Pu , Sheng Zhang , Yukai Wu , Nan Jiang , Wei Chang , Chang Li , Luming Duan

Entangled coherent states are useful for various applications in quantum information processing but they are are sensitive to loss. We propose a scheme to generate distributed entangled coherent states over a lossy environment in such a way…

Quantum Physics · Physics 2015-06-17 A. P. Lund , T. C. Ralph , H. Jeong

Optical "Schr\"odinger cat" states, the non-classical superposition of two quasi-classical coherent states, serve as a basis for gedanken experiments testing quantum physics on mesoscopic scales and are increasingly recognized as a resource…

Quantum repeaters are essential for achieving long-distance quantum communication due to photon loss, which grows exponentially with the channel distance. Current quantum repeater generations use entanglement distillation protocols, where…

Quantum Physics · Physics 2025-10-09 Iftach Yakar , Michael Ben-Or

Entanglement is a powerful concept with an enormous potential for scientific and technological advances. A central focus in modern research is to extend the generation and control of entangled states from few to many qubits, and protect…

Quantum Physics · Physics 2024-06-04 Philip Thomas , Leonardo Ruscio , Olivier Morin , Gerhard Rempe

In a quantum network that successfully creates links, shared Bell states between neighboring repeater nodes, with probability $p$ in each time slot, and performs Bell State Measurements at nodes with success probability $q<1$, the end to…

Quantum Physics · Physics 2022-04-15 Ashlesha Patil , Joshua I. Jacobson , Emily van Milligen , Don Towsley , Saikat Guha

We propose a realistic protocol to generate entanglement between quantum memories at neighboring nodes in hybrid quantum repeaters. Generated entanglement includes only one type of error, which enables efficient entanglement distillation.…

Distribution of the entangled state of trapped atomic ions to long distance using quantum repeater protocol is considered. Indeed, the long distance is divided into short parts, and then using entanglement generation and entanglement…

Quantum Physics · Physics 2021-06-04 M Ghasemi , M K Tavassoly

Decoherence is detrimental to quantum key distribution (QKD) over large distances. One of the proposed solutions is to use quantum repeaters, which divide the total distance between the users into smaller segments to minimise the effects of…

We describe a system for long-distance distribution of quantum entanglement, in which coherent light with large average photon number interacts dispersively with single, far-detuned atoms or semiconductor impurities in optical cavities.…

Quantum Physics · Physics 2007-05-23 Thaddeus D. Ladd , Peter van Loock , Kae Nemoto , William J. Munro , Yoshihisa Yamamoto

We study entanglement generation in a quantum network where repeater nodes can perform $n$-qubit Greenberger-Horne-Zeilinger(GHZ) swaps, i.e., projective measurements, to fuse $n$ imperfect-Fidelity entangled-state fragments. We show that…

Quantum Physics · Physics 2023-06-07 Eneet Kaur , Saikat Guha

The quantum repeater cell is a basic building block for a quantum network, as it allows to overcome the distance limitations due to unavoidable fiber loss in direct transmission. We demonstrate the implementation of a quantum repeater cell,…

Quantum Physics · Physics 2024-09-04 Max Bergerhoff , Omar Elshehy , Stephan Kucera , Matthias Kreis , Jürgen Eschner