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Two-step measurement of the concurrence for hyperentangled state [article]

Yu-Bo Sheng, Lan Zhou
2014 arXiv   pre-print
We describe an efficient way for measuring the concurrence of the hyperentanglement. In this protocol, the hyperentangled state is encoded in both polarization and momentum degrees of freedom.  ...  We show that the concurrences of both polarization and momentum entanglement can be conversed into the total success probability of picking up the odd-parity state and can be measured directly.  ...  In conclusion, we have described an effective way of measuring the concurrence for hyperentangled state. We first provide an alternative definition of the concurrence for the hyperentangled state.  ... 
arXiv:1401.1971v1 fatcat:awry5fxl75bnlh6y6rkqts6zlm

Telecom-band Hyperentangled Photon Pairs from a Fiber-based Source [article]

Changjia Chen, Calvin Xu, Arash Riazi, Eric Y. Zhu, Alexander Greenwood, Alexey V.Gladyshev, Peter G. Kazansky, Brian T. Kirby, Li Qian
2021 arXiv   pre-print
concurrences above 0.95 for both polarization and frequency DOFs.  ...  Hyperentanglement, the simultaneous and independent entanglement of quantum particles in multiple degrees of freedom, is a powerful resource that can be harnessed for efficient quantum information processing  ...  The polarization state that entered into the BS was not characterized concurrently with the HOMI measurement.  ... 
arXiv:2112.03369v1 fatcat:ypsciyhycjeafbsm7pkpmixd64

Distribution of high-dimensional entanglement via an intra-city free-space link

Fabian Steinlechner, Sebastian Ecker, Matthias Fink, Bo Liu, Jessica Bavaresco, Marcus Huber, Thomas Scheidl, Rupert Ursin
2017 Nature Communications  
measurements in each degree of freedom.  ...  These visibilities impose lower bounds on entanglement in each subspace individually and certify four-dimensional entanglement for the hyperentangled system.  ...  While high-visibility interference in both degrees of freedom is a clear sign for the presence of hyperentanglement, these measurements do not yet quantify entanglement in the two subspaces, nor do they  ... 
doi:10.1038/ncomms15971 pmid:28737168 pmcid:PMC5527279 fatcat:cofsnbbuybhnbmlehsi4ygx3ae

Certification of high-dimensional entanglement generated in Hong-Ou-Mandel interference [article]

Yuanyuan Chen, Sebastian Ecker, Jessica Bavaresco, Thomas Scheidl, Fabian Steinlechner, Marcus Huber, Rupert Ursin
2019 arXiv   pre-print
We show how independent measurements of polarization and frequency DOF allow for both the verification and, strictly stronger requirement, also the certification of high-dimensional entanglement in the  ...  Harnessing the generation and characterization of entanglement in high-dimensional state spaces is a necessary prerequisite towards practical quantum protocols.  ...  For analyzing the polarization correlation of the hyperentangled state, we measure two-photon interference in two mutually unbiased bases assisted by polarizers prior to detection.  ... 
arXiv:1910.07684v1 fatcat:3ma37ickirbjhfs4ujbwkxbfna

Concurrence Measurement for the Two-Qubit Optical and Atomic States

Lan Zhou, Yu-Bo Sheng
2015 Entropy  
In the paper, we mainly review some direct concurrence measurement protocols of the two-qubit optical or atomic system. We first introduce the concept of concurrence for a two-qubit system.  ...  Third, we introduce some protocols for measuring the concurrence of the atomic entanglement system.  ...  Figure 9 . 9 The schematic of the concurrence measurement for the momentum entanglement. Two pairs of hyperentangled states are emitted by the source (S).  ... 
doi:10.3390/e17064293 fatcat:3bzdp6qkknaipassw7zqnnpkk4

Experimental entanglement distillation using Schmidt projection on multiple qubits [article]

Taehyun Kim, Franco N. C. Wong
2008 arXiv   pre-print
We implement the Schmidt projection protocol by applying single-photon two-qubit quantum logic to a partially hyperentangled four-qubit input state.  ...  The basic elements of the procedure are characterized and we confirm that the output of Schmidt projection is always maximally entangled independent of the input entanglement quality and that the measured  ...  (a) Measured coincidence rate of the two parallel and two orthogonal polarization terms of the output state for input state with θ = 35.9 • .  ... 
arXiv:0808.3270v1 fatcat:m2eji53nvzcetnvixwgtmoex3a

Path-polarization hyperentangled and cluster states of photons on a chip

Mario Arnolfo Ciampini, Adeline Orieux, Stefano Paesani, Fabio Sciarrino, Giacomo Corrielli, Andrea Crespi, Roberta Ramponi, Roberto Osellame, Paolo Mataloni
2016 Light: Science & Applications  
Hyperentangled photon states (i.e. states showing entanglement in multiple DOFs) have demonstrated significant implications for both fundamental physics tests and quantum communication and computation.  ...  Encoding many qubits in different degrees of freedom (DOFs) of single photons is one of the routes towards enlarging the Hilbert space spanned by a photonic quantum state.  ...  ACKNOWLEDGEMENTS This work was supported by the European Union through the project FP7-ICT-2011-9-600838 (QWAD Quantum Waveguides Application and Development; www.qwad-project.eu) and by FIRB, Futuro in  ... 
doi:10.1038/lsa.2016.64 pmid:30167159 fatcat:yst6fos34fg3fj6fronjqow3d4

Measurement of the Entanglement between Photonic Spatial Modes in Optical Fibers

Yoonshik Kang, Jaekwon Ko, Sang Min Lee, Sang-Kyung Choi, Byoung Yoon Kim, Hee Su Park
2012 Physical Review Letters  
Quantum states over the two lowest-order spatial modes are measured with highly efficient spatial-mode analyzers based on acousto-optics.  ...  Quantum state tomography verifies the entanglement of the spatial-domain Bell state.  ...  For example, the measurement with a step-phase plate for one photon of an entangled pair in [16] is only applicable to states in the form of sinj0i þ cosj1i with real .  ... 
doi:10.1103/physrevlett.109.020502 pmid:23030140 fatcat:qvs2usjunvh3tjztf7iub6pozi

Effects of spectral entanglement in polarization-entanglement swapping and type-I fusion gates

Travis S. Humble, Warren P. Grice
2008 Physical Review A. Atomic, Molecular, and Optical Physics  
Specifically, when spectral differences correlate with polarization, the optimal source configuration is different for the two protocols.  ...  We quantify the success of the entanglement swapping and fusion gates by calculating the bipartite concurrence and residual tangle, respectively, in terms of the joint spectral probability amplitudes of  ...  The case of embedded Bell-state analysis is one recent example of how hyperentanglement can greatly improve the efficiency of a protocol or measurement ͓15,16͔.  ... 
doi:10.1103/physreva.77.022312 fatcat:4s2fffkruje5dcm6jcfxqw3exe

Teleportation-based realization of an optical quantum two-qubit entangling gate

W.-B. Gao, A. M. Goebel, C.-Y. Lu, H.-N. Dai, C. Wagenknecht, Q. Zhang, B. Zhao, C.-Z. Peng, Z.-B. Chen, Y.-A. Chen, J.-W. Pan
2010 Proceedings of the National Academy of Sciences of the United States of America  
Therefore, the construction of a quantum computer can be simply based on some multi-particle entangled states, Bell state measurements and single-qubit operations.  ...  In recent years, there has been heightened interest in quantum teleportation, which allows for the transfer of unknown quantum states over arbitrary distances.  ...  We acknowledge Tracy Li for proofreading the manuscript. This work was supported by the National Natural Science  ... 
doi:10.1073/pnas.1005720107 pmid:21098305 pmcid:PMC3000260 fatcat:uc6begarmbeb3kj5fwg5ggotoy

Entangled photon pairs from quantum dots embedded in a self-aligned cavity [article]

Laia Ginés and Carlo Pepe and Junior Gonzales and Niels Gregersen and Sven Höfling and Christian Schneider and Ana Predojević
2020 arXiv   pre-print
Our system, which is based on a self-aligned quantum dot-micro-cavity structure, erases the need for complex steps of lithography and nanofabrication.  ...  The achieved pair collection efficiency is 4 times larger than the state-of-the art.  ...  This step would further enhance the versatility of the device by allowing also for the generation of polarization and hyperentanglement.  ... 
arXiv:2010.01555v2 fatcat:rvc6wv5cfvbprim5sclqxx2uum

Time-bin entangled photon pairs from quantum dots embedded in a self-aligned cavity

Laia Ginés, Carlo Pepe, Junior Gonzales, Niels Gregersen, Sven Höfling, Christian Schneider, Ana Predojević
2021 Optics Express  
The achieved pair collection efficiency is 4 times larger than the state-of-the art for this application.  ...  Our system, which is based on a self-aligned quantum dot- micro-cavity structure, erases the need for complex steps of lithography and nanofabrication.  ...  The authors declare no conflicts of interest.  ... 
doi:10.1364/oe.411021 pmid:33771002 fatcat:a3egzxncjne7rpwvpoty3zblum

Measurability of D-concurrence

N. Karimi, A. Heshmati, M. Yahyavi, M. A. Jafarizadeh, A. Mohammadzadeh
2019 Scientific Reports  
We first introduce the concept of D-concurrence for a bipartite system. Then we explain the method of measuring this entanglement measure for the pure state.  ...  In this paper, we present a direct method for experimental determination of the D-concurrence of an arbitrary bipartite pure state.  ...  Acknowledgements This research has been supported by University of Tabriz, Farhangian University of Tehran, and Shabestar Branch Islamic Azad University.  ... 
doi:10.1038/s41598-019-54247-2 pmid:31857599 pmcid:PMC6923386 fatcat:326oytzenjb3fdjv3exvrfgnwi

Nonlocal Generalized Quantum Measurements of Spin Products Without Maximal Entanglement [article]

Pierre Vidil, Keiichi Edamatsu
2019 arXiv   pre-print
The relation between measurement strength and the amount of ancillary entanglement needed is made explicit, bringing a new perspective on the links that tie quantum nonlocality, entanglement and information  ...  We present a new approach to this problem, using the language of generalized quantum measurements, to show that it is actually possible to measure a nonlocal spin product observable without necessarily  ...  Hereafter, we shall use the concurrence [49] as our main measure of entanglement, defined as follows for a pure two-qubit state: C ≡ 2λ 0 λ 1 (13) where λ 0 and λ 1 are the Schmidt coefficients.  ... 
arXiv:1912.07135v1 fatcat:2zxdv5wwqrfblelat2amwniw7a

Measures and dynamics of entanglement

A. Buchleitner, A. R.R. Carvalho, F. Mintert
2008 The European Physical Journal Special Topics  
We briefly review our recent work on how to quantify and how to measure the entanglement inscribed into quantum states which evolve under incoherent environment coupling. 48 The European Physical Journal  ...  The results summarized above are the product of a collective effort between Warsaw, Rio de Janeiro, and Dresden.  ...  The collaboration between Dresden and Warsaw was funded by VolkswagenStiftung, the one between Dresden and Rio by the DAAD, within a PostDoc fellowship (F.M.), and the PROBRAL program.  ... 
doi:10.1140/epjst/e2008-00692-0 fatcat:eagg5vkxfngfvlpyvmab2bxdfm
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