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We show that single-photon entangled states of the form |0>|1>+|1>|0> can be purified with a simple linear-optics based protocol, which is eminently feasible with current technology. Besides its conceptual interest, this result is relevant…

Quantum Physics · Physics 2009-11-13 Nicolas Sangouard , Christoph Simon , Thomas Coudreau , Nicolas Gisin

An entanglement purification protocol (EPP) aims to transform multiple noisy entangled states into a single entangled state with higher fidelity. In this work we consider EPPs that always yield an output fidelity no worse than each of the…

Quantum Physics · Physics 2025-07-14 Allen Zang , Xinan Chen , Eric Chitambar , Martin Suchara , Tian Zhong

We propose two schemes for concentration of hyperentanglement of nonlocal multipartite states which are simultaneously entangled in the polarization and spatial modes. One scheme uses an auxiliary singlephoton state prepared according to…

Quantum Physics · Physics 2016-01-20 Xihan Li , Shohini Ghose

Genuine multipartite entanglement (GME) represents the strongest form of entanglement in multipartite systems, providing significant advantages in various quantum information processing tasks. In this work, we propose an experimentally…

We report on the experimental generation of an entangled state with a spectrally pure heralded single-photon state and a weak coherent state. By choosing group-velocity matching in the nonlinear crystal, our system for producing entangled…

We have applied an entanglement purification protocol to produce a single entangled pair of photons capable of violating a CHSH Bell inequality from two pairs that individually could not. The initial poorly-entangled photons were created by…

Quantum Physics · Physics 2009-11-11 P. Walther , K. J. Resch , C. Brukner , A. M. Steinberg , J. -W. Pan , A. Zeilinger

The Mermin inequality provides a criterion for experimentally ruling out local-realistic descriptions of multiparticle systems. A violation of this inequality means that the particles must be entangled, but does not, in general, indicate…

Quantum Physics · Physics 2011-02-25 Mark S. Everitt , Martin L. Jones , Benjamin T. H. Varcoe , Jacob A. Dunningham

Microwave photons have become very important qubits in quantum communication as the first quantum satellite has been launched successfully. Therefore, it is a necessary and meaningful task for ensuring the high security and efficiency of…

Quantum Physics · Physics 2017-12-06 Hao Zhang , Qian Liu , Xu-Sheng Xu , Jun Xiong , Ahmed Alsaedi , Tasawar Hayat , Fu-Guo Deng

We study the entanglement of purification (EoP) of subsystem $A$ and B in conformal field theories (CFTs) stressing on its relation to unitary operations of disentanglement, if the auxiliary subsystem $\tilde{A}$ adjoins $A$ and…

High Energy Physics - Theory · Physics 2019-10-02 Wu-zhong Guo

In this work, we introduce a unified method to characterize and measure multipartite entanglement using the framework of thermodynamics. A family of the new entanglement measures is proposed: \textit{ergotropic-gap concentratable…

Quantum Physics · Physics 2026-02-02 Chen-Ming Bai , Yu Luo

We report a practical non-postselection entanglement concentration scheme in which a maximally entangled Bell-state photon pair is produced from two pairs of partially (or non-maximally) entangled photons. Since this scheme is built only…

Quantum Physics · Physics 2016-02-23 Myung-Joong Hwang , Yoon-Ho Kim

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

Whether entanglement in a state can be detected, distilled, and quantified without full state reconstruction is a fundamental open problem. We demonstrate a new scheme encompassing these three tasks for arbitrary two-qubit entanglement, by…

Quantum Physics · Physics 2010-12-03 H. S. Park , S. -S. B. Lee , H. Kim , S. -K. Choi , H. -S. Sim

We propose a feasible scheme to create $n$-party ($n\geq 2$) polarization-entangled photon states in a controllable way. The scheme requires only single-photon sources, single-photon quantum non-demolition measurement (SP-QNDM) and simple…

Quantum Physics · Physics 2007-05-23 Zeng-Bing Chen , Jian-Wei Pan , Yong-De Zhang

One of the fundamental concepts of quantum information theory is that of entanglement purification; that is, the transformation of a partially entangled state into a smaller-dimensional, more completely entangled state. Of particular…

Quantum Physics · Physics 2008-02-03 Eric M. Rains

The atom-photon entanglement of dressed atom and its spontaneous emission in a Double-Lambda closed-loop atomic system is studied in multi-photon resonance condition. It is shown that, even in the absence of quantum interference due to the…

Atomic and Molecular Clusters · Physics 2015-02-03 Zeinab Kordi , Saeed Ghanbari , Mohammad Mahmoudi

High-visibility quantum interference between independent photons is essential for demonstrating multi-photon quantum information processing, and it is closely linked to the spectral purity of correlated photon pairs. In this study, we…

Quantum Physics · Physics 2026-01-12 Hsin-Pin Lo , Kai Asaoka , Hiroki Takesue

We investigate duality in entanglement of a bipartite multi-photon system generated from a coherent state of light. The system can exhibit polarization entanglement if the two parts are distinguished by their parity, or parity entanglement…

Quantum Physics · Physics 2016-08-17 Su-Yong Lee , Chang-Woo Lee , Pawel Kurzynski , Dagomir Kaszlikowski , Jaewan Kim

Entanglement is a key resource for quantum computing, sensing, and communication, however it is highly susceptible to decoherence. To address this, quantum optics has explored filtering techniques like photon ancillas and Rydberg atom…

We present two linear optical schemes using nonideal photodetectors to demonstrate inseparability of W-type N-partite entangled states containing only a single photon. First, we show that the pairwise entanglement of arbitrary two modes…

Quantum Physics · Physics 2009-11-13 Hyunchul Nha , Jaewan Kim