Long-Distance Entanglement Purification for Quantum Communication

Hu, Xiaomin; Huang, Cen-Xiao; Sheng, Yu‐Bo; Zhou, Lan; Liu, Bi-Heng; Guo, Yu; Zhang, Chao; Xing, Wen-Bo; Huang, Yun‐Feng; Li, Chuan‐Feng; Guo, Guang-Can

doi:10.1103/physrevlett.126.010503

Cited by 173 publications

(98 citation statements)

References 41 publications

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“…The hyper-entangled state has been used in quantum dense coding to measure all the Bell state pairs produced in one degree of freedom 32 . Using cross-Kerr nonlinearity, it is also possible to distinguish all the hyper-entangled Bell states in multiple degrees of freedom 70 , 71 . This enables us to perform quantum communication with larger channel capacity.…”

Section: Resultsmentioning

confidence: 99%

Creating heralded hyper-entangled photons using Rydberg atoms

et al. 2021

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Entangled photon pairs are a fundamental component for testing the foundations of quantum mechanics, and for modern quantum technologies such as teleportation and secured communication. Current state-of-the-art sources are based on nonlinear processes that are limited in their efficiency and wavelength tunability. This motivates the exploration of physical mechanisms for entangled photon generation, with a special interest in mechanisms that can be heralded, preferably at telecommunications wavelengths. Here we present a mechanism for the generation of heralded entangled photons from Rydberg atom cavity quantum electrodynamics (cavity QED). We propose a scheme to demonstrate the mechanism and quantify its expected performance. The heralding of the process enables non-destructive detection of the photon pairs. The entangled photons are produced by exciting a rubidium atom to a Rydberg state, from where the atom decays via two-photon emission (TPE). A Rydberg blockade helps to excite a single Rydberg excitation while the input light field is more efficiently collectively absorbed by all the atoms. The TPE rate is significantly enhanced by a designed photonic cavity, whose many resonances also translate into high-dimensional entanglement. The resulting high-dimensionally entangled photons are entangled in more than one degree of freedom: in all of their spectral components, in addition to the polarization—forming a hyper-entangled state, which is particularly interesting in high information capacity quantum communication. We characterize the photon comb states by analyzing the Hong-Ou-Mandel interference and propose proof-of-concept experiments.

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Section: Resultsmentioning

confidence: 99%

Creating heralded hyper-entangled photons using Rydberg atoms

et al. 2021

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“…4 shows the normalized experimental measured coincidence count rate vs. difference of the polarizers angle = | − | for two cases: one angle is fixed at 0 • (45 • ) and the other one changes. By fitting the theoretical expression (7) to the experimental coincidence pints, we obtain the average transmittance as ̄f it = = 0.748 ± 0.015. To calculate the Freedman's parameter F , we measured the CC rates for different values of Φ [see Table 3].…”

Section: Freedman's Testmentioning

confidence: 99%

“…However, there are different methods to generate the polarization entangled photon pairs, such as the non-post selective two-photon resonant excitation scheme on a single semiconductor quantum dot [5] and the high-harmonic generation method plus a mixed co-propagating elliptically polarized waves in an isotropic media [6]. Moreover, very recently, it has been proposed [7] an interesting method to generate the temperature, which means that need no cooling, and have capability to be scalable in order to be commercialized. During these three decades, the SPDC in NLCs has been a variety range of applications in quantum metrology, quantum communication, quantum computing, quantum information, and quantum thermodynamics (for a review, see Ref.…”

Section: Introductionmentioning

confidence: 99%

Nonlocal realism tests and quantum state tomography in Sagnac-based type-II polarization-entanglement SPDC-source

Motazedifard

Madani

Dashkasan

et al. 2021

Heliyon

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We have experimentally created a robust, ultrabright and phase-stable polarization-entangled state close to maximally entangled Bell-state with %98-fidelity using the type-II spontaneous parametric down-conversion (SPDC) process in periodically-poled KTiOPO 4 (PPKTP) collinear crystal inside a Sagnac interferometer (SI). Bell inequality measurement, Freedman's test, as the different versions of CHSH inequality, and also visibility test which all can be seen as the nonlocal realism tests, imply that our created entangled state shows a strong violation from the classical physics or any hidden-variable theory. We have obtained very reliable and very strong Bell violation as = 2.78 ± 0.01 with high brightness  HV = %(99.969 ± 0.003) and  DA = %(96.751 ± 0.002) and very strong violation due to Freedman test as F = 0.01715 ± 0.00001. Furthermore, using the tomographic reconstruction of quantum states together a maximum-likelihood-technique (MLT) as the numerical optimization, we obtain the physical non-negative definite density operator which shows the nonseparability and entanglement of our prepared state. By having the maximum likelihood density operator, we calculate some important entanglement-measures and entanglement entropies. The Sagnac configuration provides bidirectional crystal pumping yields to high-rate entanglement source which is very applicable in quantum communication, sensing and metrology as well as quantum information protocols, and has potential to be used in quantum illuminationbased LIDAR and free-space quantum key distribution (QKD).

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“…Therefore, prior to the application, we should recover the degraded entangled state into the maximally entangled state. The method to recover the mixed state into the maximally entangled state is called the entanglement purification, 26‐34 while the method to recover the pure less entangled state into the maximally entangled state, which will be detailed here, is called the entanglement concentration 35‐42 . In 1996, Bennett et al proposed the concept of entanglement concentration and put forward the first entanglement concentration protocol (ECP), 35 which called the Schmidt decomposition protocol.…”

Section: Introductionmentioning

confidence: 99%

Logic W‐state concentration with parity check

Zhou

Liu

et al. 2021

Quantum Engineering

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Logic W state, which replaces each physical qubit in a W state with a Greenberger–Horne–Zeilinger state is robust against photon transmission loss in long‐distance quantum communication. In practical application, the environmental noise may make maximally entangled logic W state degrade to less entangled state, which largely limits its application. In this article, we propose an efficient entanglement concentration protocol (ECP) for logic W state, which can recover the less entangled logic W state into the maximally entangled logic W state. Our ECP relies on the nondemolition polarization parity check (PPC) gate constructed with cross‐Kerr nonlinearity. The distilled maximally entangled logic W state can be preserved for other application. Moreover, when the ECP fails, we can repeat the ECP to further concentrate the distilled less entangled logic W state. By repeating the ECP, the total success probability can be effectively increased. Based on above features, this ECP may be useful in quantum communication field.

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Long-Distance Entanglement Purification for Quantum Communication

Cited by 173 publications

References 41 publications

Creating heralded hyper-entangled photons using Rydberg atoms

Creating heralded hyper-entangled photons using Rydberg atoms

Nonlocal realism tests and quantum state tomography in Sagnac-based type-II polarization-entanglement SPDC-source

Logic W‐state concentration with parity check

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