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High-dimensional entanglement offers a variety of advantages for both fundamental and applied applications in quantum information science. A central building block for such applications is a programmable processor of entangled states, which…

Quantum Physics · Physics 2022-08-09 Ohad Lib , Kfir Sulimany , Yaron Bromberg

Using a spontaneous-downconversion photon source, we produce true non-maximally entangled states, i.e., without the need for post-selection. The degree and phase of entanglement are readily tunable, and are characterized both by a standard…

Quantum Physics · Physics 2009-10-31 Andrew G. White , Daniel F. V. James , Philippe H. Eberhard , Paul G. Kwiat

The ability to engineer pairs of entangled photons is essential to quantum information science, and generating these states using spontaneous parametric down-conversion (SPDC) in nano- and micrometer-scale materials offers numerous…

Quantum Physics · Physics 2025-03-11 Nicholas J. Sorensen , Vitaliy Sultanov , Maria V. Chekhova

We explore the connection between quantum entanglement and the exchange symmetry of the states of N identical particles. Each particle has n-levels. The N particles span the nN dimensional Hilbert space. We shall call the general state of…

Quantum Physics · Physics 2007-05-23 Jagdish Rai , Suranjana Rai

A method for exploring photon-number entangled states with weak nonlinearities is described. We show that it is possible to create and detect such entanglement at various scales, ranging from microscopic to macroscopic systems. In the…

Quantum Physics · Physics 2015-10-28 Yingqiu He , Dong Ding , Fengli Yan , Ting Gao

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 bipartite multiphoton entangled state is created through stimulated parametric down-conversion of strong laser pulses in a nonlinear crystal. It is shown how detectors that do not resolve photon number can be used to analyze such…

Quantum Physics · Physics 2007-05-23 H. S. Eisenberg , G. Khoury , G. A. Durkin , C. Simon , D. Bouwmeester

High-dimensional quantum systems offer a number of advantages in larger information capacity, stronger noise resiliency, higher improved efficiency and accuracy over the qubit systems. In quantum communication the maximally entangled states…

Quantum Physics · Physics 2026-04-15 Si-Qi Du , Guo-Zhu Song , Hai-Rui Wei

Entangled photon pairs -- discrete light quanta that exhibit non-classical correlations -- play a crucial role in quantum information science (for example in demonstrations of quantum non-locality and quantum cryptography). At the…

Quantum Physics · Physics 2009-11-07 Antia Lamas-Linares , John C. Howell , Dik Bouwmeester

High-dimensional entanglement in the form of transverse spatial correlation between a pair of photons generated via spontaneous parametric downconversion is not only a valuable resource in many academic and real-life applications but also…

Quantum Physics · Physics 2025-08-18 Rounak Chatterjee , Vikas S Bhat , Kiran Bajar , Sushil Mujumdar

In their seminal paper, Einstein Podolsky and Rosen (EPR) had introduced a momentum entangled state for two particles. That state, referred to as the EPR state, has been widely used in studies on entangled particles with continuous degrees…

Quantum Physics · Physics 2025-10-24 Rashi Adhikari , Mohd Shoaib Qureshi , Tabish Qureshi

Multi-photon states from parametric down-conversion can be entangled both in polarization and photon number. Maximal high-dimensional entanglement can be concentrated from these states via photon counting. This makes them natural candidates…

Quantum Physics · Physics 2009-11-07 Gabriel A. Durkin , Christoph Simon , Dik Bouwmeester

Entangled photon sources (EPSs) are pivotal in advancing quantum communication, computing and sensing. The demand for deploying efficient, robust EPSs in the field, characterized by exceptional (phase) stability, has become increasingly…

Quantum Physics · Physics 2024-07-12 Giacomo Paganini , Alvaro Cuevas , Robin Camphausen , Alexander Demuth , Valerio Pruneri

A workflow for evaluation of entanglement source quality is proposed. Based on quantum state density matrices obtained from theoretical models and experimental data, we make an estimate of a potential performance of a quantum entanglement…

Quantum Physics · Physics 2021-04-27 Radim Hošák , Ivo Straka , Ana Predojević , Radim Filip , Miroslav Ježek

Entanglement--one of the most delicate phenomena in nature--is an essential resource for quantum information applications. Large entangled cluster states have been predicted to enable universal quantum computation, with the required single-…

Hyperentanglement offers enhanced capacity for quantum information processing and communication protocols, especially in combination with robust high-dimensional degrees of freedom such as frequency-bin encoding. Here, we present a…

Quantum Physics · Physics 2026-03-05 Tommaso Faleo , Fabian Steinhauser , Gregor Weihs , Stefan Frick , Robert Keil

We propose an optimal nonlocal entanglement concentration protocol (ECP) for multi-photon systems in a partially entangled pure state, resorting to the projection measurement on an additional photon. One party in quantum communication first…

Quantum Physics · Physics 2012-02-10 Fu-Guo Deng

Spontaneous parametric down-conversion (SPDC) is a reliable platform for entanglement generation. Routinely, a coherent laser beam is an essential prerequisite for pumping the nonlinear crystal. Here we break this barrier to generate…

Quantum Physics · Physics 2022-11-09 Wuhong Zhang , Diefei Xu , Lixiang Chen

The reliable distribution of high-dimensional entangled quantum states, an important resource in quantum technologies, through optical fibre networks is challenging due to the need to maintain coherence across multiple modes. Here we…

Entangled photon sources (EPS) are essential for quantum science and technology. Despite advancements in integrated optical platforms like thin-film lithium niobate, a scalable, high-performance, chip-scale EPS has remained elusive. We…