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

Steinlechner, Fabian; Ecker, Sebastian; Fink, Matthias; Bo, Liu; Bavaresco, Jessica; Huber, Marcus; Scheidl, Thomas; Ursin, Rupert

doi:10.1038/ncomms15971

Cited by 157 publications

(112 citation statements)

References 75 publications

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“…The experimental data showed lower bound visibilities of 98% and 91% for polarization and energytime respectively, corresponding to a minimum value of 0.94 and 0.77 ebits (entangled bits) of entanglement of formation [124]. Furthermore, by considering the combined hyper-entangled state, they obtained 1.46 of ebits of entanglement of formation [124] and a Bellstate fidelity of 0.94, certifying the dimensionality of the system to d = 4. These experiments certify the capability of employing high-dimensional quantum states, encoded in multiple degrees of freedom, for free-space links.…”

Section: Free-space Linksmentioning

confidence: 83%

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High‐Dimensional Quantum Communication: Benefits, Progress, and Future Challenges

et al. 2019

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In recent years, there has been a rising interest in high‐dimensional quantum states and their impact on quantum communication. Indeed, the availability of an enlarged Hilbert space offers multiple advantages, from larger information capacity and increased noise resilience, to novel fundamental research possibilities in quantum physics. Multiple photonic degrees of freedom have been explored to generate high‐dimensional quantum states, both with bulk optics and integrated photonics. Furthermore, these quantum states have been propagated through various channels, for example, free‐space links, single‐mode, multicore, and multimode fibers, and also aquatic channels, experimentally demonstrating the theoretical advantages over 2D systems. Here, the state‐of‐the‐art on the generation, propagation, and detection of high‐dimensional quantum states is reviewed. Quantum communication with states living in d‐dimensional Hilbert spaces, qudits, yields great benefits. However, qudits generation, transmission, and detection is not a simple task to accomplish. This review presents the state‐of‐the‐art on the generation, propagation, and measurement of high‐dimensional quantum states, highlighting their advantages, issues, and future perspectives.

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Section: Free-space Linksmentioning

confidence: 83%

“…Figure 3 summarizes the time-encoding schemes we have discussed. Time encoding has been exploited in a large number of experiments, mostly focused on quantum communication and quantum cryptography [48,[123][124][125][126].…”

Section: Bulk Optics Schemesmentioning

confidence: 99%

High‐Dimensional Quantum Communication: Benefits, Progress, and Future Challenges

et al. 2019

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“…Furthermore, it is well suited for the real-time benchmarking of quantum memories using OAM states [37,38], and for the parallel processing of the information in many memories systems [39]. Lastly, it could also find a niche as a feedback tool in the positioning of long-distance free-space quantum communication channels forming intra-city quantum cryptographic networks [40].…”

Section: Discussion and Outlookmentioning

confidence: 99%

Fast camera spatial characterization of photonic polarization entanglement

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et al. 2020

Sci Rep

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Scalable technologies to characterize the performance of quantum devices are crucial to creating large quantum networks and quantum processing units. Chief among the resources of quantum information processing is entanglement. Here we describe the full temporal and spatial characterization of polarization-entangled photons produced by Spontaneous Parametric Down Conversions using an intensified high-speed optical camera, Tpx3Cam. This novel technique allows for precise determination of Bell inequality parameters with minimal technical overhead, as well as novel characterization methods of the spatial distribution of entangled quantum information. This could lead to multiple applications in Quantum Information Science, opening new perspectives for the scalability of quantum experiments. arXiv:1808.06720v2 [quant-ph] 13 Sep 2018 Recent developments have shown that spatial characterization of entangled states with single-photon sensitive cameras provides access to a myriad of new possibilities, such as imaging high-dimensional entanglement [8], generalized Bell inequalities [9] and the study of Einstein-Podolsky-Rosen non-localities [10, 11]. However, these measurements used resource-intensive methods, such as sequential scanning or multiple standalone detectors.Early studies of entanglement with modern imagers used an electron-multiplying CCD (EM-CCD) camera with an effective area of 201 × 201 pixels and frame readout-rate of 5Hz [8].Albeit the EMCCD quantum efficiency was up to 90%, prolonged exposure time of about 1ms, requires this device to operate at very small photon-rates to avoid multiple photons in the same frame. Furthermore, to achieve single-photon level sensitivity the EMCCD camera operated at a low temperature of −85 o C.Further progression on quantum imaging with cameras was achieved using intensified CMOS and CCD cameras [12][13][14][15][16][17]. Flexible readout architectures allow kHz continuous framing rates in CMOS cameras. Additionally, nano-second scale time resolution for single photons can be achieved by gating image intensifiers. For example, an intensified sCMOS camera was used to observe Hong-Ou-Mandel interference [18], where the photons were collected on

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“…This was first demonstrated with photonic OAM, time-frequency, and polarisation, where entanglement was certified in each degree-of-freedom via a Bell CHSH test [170]. More recently, a hyperentangled state of polarisation and energytime was transmitted over 1.2km of free-space, and highdimensional entanglement in d ent = 4 was certified via an entanglement witness relating visibility to state fi-delity [133].…”

Section: S 2 Gmementioning

confidence: 99%

Entanglement certification from theory to experiment

et al. 2018

Self Cite

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Entanglement is an important resource that allows quantum technologies to go beyond the classically possible. There are many ways quantum systems can be entangled, ranging from the archetypal two-qubit case to more exotic scenarios of entanglement in high dimensions or between many parties. Consequently, a plethora of entanglement quantifiers and classifiers exist, corresponding to different operational paradigms and mathematical techniques.However, for most quantum systems, exactly quantifying the amount of entanglement is extremely demanding, if at all possible. This is further exacerbated by the difficulty of experimentally controlling and measuring complex quantum states. Consequently, there are various approaches for experimentally detecting and certifying entanglement when exact quantification is not an option, with a particular focus on practically implementable methods and resource efficiency. The applicability and performance of these methods strongly depends on the assumptions one is willing to make regarding the involved quantum states and measurements, in short, on the available prior information about the quantum system. In this review we discuss the most commonly used paradigmatic quantifiers of entanglement. For these, we survey state-of-the-art detection and certification methods, including their respective underlying assumptions, from both a theoretical and experimental point of view.In the early twentieth century, the phenomenon of quantum entanglement rose to prominence as a central feature of the famous thought experiment by Einstein, Podolsky, and Rosen [1]. Initially disregarded as a mathematical artefact that showcases the incompleteness of quantum theory, the properties of entanglement were largely ignored until 1964, when John Bell famously proposed an experimentally testable inequality able to distinguish between the predictions of quantum mechanics and those of any local-realistic theory [2]. With the advent of the first experimental tests [3], spearheaded by , emerged the realisation that entanglement constitutes a resource for information processing *

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

Cited by 157 publications

References 75 publications

High‐Dimensional Quantum Communication: Benefits, Progress, and Future Challenges

High‐Dimensional Quantum Communication: Benefits, Progress, and Future Challenges

Fast camera spatial characterization of photonic polarization entanglement

Entanglement certification from theory to experiment

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