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Entanglement concentration is a critical technique to prevent degraded fidelity and security in long-distance quantum communication. We propose novel practical entanglement concentration protocols (ECPs) for less-entangled Bell and…

Quantum Physics · Physics 2023-04-05 Gui-Long Jiang , Wen-Qiang Liu , Hai-Rui Wei

Sources of entangled photon pairs using two parametric down-converters are capable of generating interchangeable entanglement in two different degrees of freedom. The connection between these two degrees of freedom allows the control of the…

Quantum Physics · Physics 2009-11-07 D. P. Caetano , P. H. Souto Ribeiro

We propose a nonlocal entanglement concentration protocol (ECP) for $N$-photon systems in a partially entangled W state, resorting to some ancillary single photons and the parity-check measurement based on cross-Kerr nonlinearity. One party…

Quantum Physics · Physics 2015-06-05 Fang-Fang Du , Tao Li , Bao-Cang Ren , Hai-Rui Wei , Fu-Guo Deng

We use a single trapped 40Ca+ ion as a resonant, polarization-sensitive absorber to detect and characterize the entanglement of tunable narrowband photon pairs from a spontaneous parametric down-conversion source. Single-photon absorption…

Quantum Physics · Physics 2013-04-22 J. Huwer , J. Ghosh , N. Piro , M. Schug , F. Dubin , J. Eschner

We present an entanglement concentration protocols (ECPs) for less-entangled W state with quantum-dot and microcavity coupled system. The present protocol uses the quantum nondemolition measurement on the spin parity to construct the parity…

Quantum Physics · Physics 2015-06-05 Yu-Bo Sheng , Lan Zhou , Chuan Wang , Sheng-Mei Zhao

Using a spontaneous parametric-downconversion source of photon pairs, we are working towards the creation of arbitrary 2-qubit quantum states with high fidelity. Currently, all physically allowable combinations of polarization entanglement…

Quantum Physics · Physics 2007-05-23 Paul Kwiat , Joe Altepeter , David Branning , Evan Jeffrey , Nicholas Peters , Tzu-Chieh Wei

Optical parametric down-conversion is a common source for the generation of non-classical correlated photonic states. Using a parametric down-conversion source and photon-number resolving detectors, we measure the two-mode photon-number…

Quantum Physics · Physics 2014-02-04 L. Dovrat , M. Bakstein , D. Istrati , E. Megidish , A. Halevy , H. S. Eisenberg

We report on a new technique for entanglement distillation of the bipartite continuous variable state of spatially correlated photons generated in the spontaneous parametric down-conversion process (SPDC), where tunable non-Gaussian…

Quantum Physics · Physics 2018-05-18 E. S. Gómez , P. Riquelme , M. A. Solis-Prosser , P. González , E. Ortega , G. B. Xavier , G. Lima

We report the demonstration of a bulk, intrinsically phase-stable source of polarization- and time-energy-entangled photon pairs at 810nm and 1550nm, directly coupled into single-mode optical fibers. This highly non-degenerate wavelength…

Entanglement purification is a very important element for long-distance quantum communication. Different from all the existing entanglement purification protocols (EPPs) in which two parties can only obtain some quantum systems in a mixed…

Quantum Physics · Physics 2010-03-15 Yu-Bo Sheng , Fu-Guo Deng

Photonic-based qubits and integrated photonic circuits have enabled demonstrations of quantum information processing (QIP) that promises to transform the way in which we compute and communicate. To that end, sources of…

Entanglement purification and distillation protocols are essential for harnessing the full potential of quantum communication technologies. Multiple strategies have been proposed to approach and optimize such protocols, most however…

Quantum Physics · Physics 2025-04-16 Jorge Miguel-Ramiro , Alexander Pirker , Wolfgang Dür

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

We suggest and demonstrate a scheme for coherent nonlocal compensation of pure phase objects based on two-photon polarization and momentum entangled states. The insertion of a single phase object on one of the beams reduces the purity of…

Quantum Physics · Physics 2015-05-28 S. Cialdi , D. Brivio , E. Tesio , M. G. A. Paris

We present two protocols for the single-photon entanglement concentration. With the help of the 50:50 beam splitter, variable beam splitter and an auxiliary photon, we can concentrate a less-entangled single-photon state into a maximally…

Quantum Physics · Physics 2012-10-01 Lan Zhou

We investigate entanglement purification protocols based on hashing, where a large number of noisy entangled pairs is jointly processed to obtain a reduced number of perfect, noiseless copies. While hashing and breeding protocols are the…

Quantum Physics · Physics 2014-07-15 M. Zwerger , H. J. Briegel , W. Dür

Sources of entangled photon pairs are a key component in both fundamental tests of quantum theory and practical applications such as quantum key distribution and quantum computing. In this work, we describe and characterize a source of…

Quantum Physics · Physics 2013-10-03 Terence E. Stuart , Joshua A. Slater , Felix Bussieres , Wolfgang Tittel

Entangled photon sources are essential for quantum information applications, including quantum computation, quantum communication, and quantum metrology. Periodically poled (PP) crystals are commonly used to generate bright photon sources…

Quantum Physics · Physics 2025-05-29 Ilhwan Kim , Yosep Kim , Yong-Su Kim , Kwang Jo Lee , Hyang-Tag Lim

We suggest and demonstrate a scheme to compensate spatial and spectral decoherence effects in the generation of polarization entangled states by type-I parametric downconversion. In our device a programmable spatial light modulator imposes…

Quantum Physics · Physics 2015-05-19 Simone Cialdi , Davide Brivio , Matteo G A Paris

Miniaturised entangled photon sources are highly demanded for the development of integrated quantum photonics. Since the invention of subwavelength optical metasurfaces and their successes at replacing bulky optical components, the…