Browsing by Author "Gonzalez-Raya, Tasio"
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Item Open-Air Microwave Entanglement Distribution for Quantum Teleportation(American Physical Society, 2022-10) Gonzalez-Raya, Tasio; Casariego, Mateo; Fesquet, Florian; Renger, Michael; Salari, Vahid; Möttönen, Mikko; Omar, Yasser; Deppe, Frank; Fedorov, Kirill G.; Sanz, Mikel; Department of Applied Physics; Centre of Excellence in Quantum Technology, QTF; Quantum Computing and Devices; University of the Basque Country; Universidade de Lisboa; Bayerische Akademie der WissenschaftenMicrowave technology plays a central role in current wireless communications, including mobile communication and local area networks. The microwave range shows relevant advantages with respect to other frequencies in open-air transmission, such as low absorption losses and low-energy consumption, and in addition, it is the natural working frequency in superconducting quantum technologies. Entanglement distribution between separate parties is at the core of secure quantum communications. Therefore, understanding its limitations in realistic open-air settings, especially in the rather unexplored microwave regime, is crucial for transforming microwave quantum communications into a mainstream technology. Here, we investigate the feasibility of an open-air entanglement distribution scheme with microwave two-mode squeezed states. First, we study the reach of direct entanglement transmission in open air, obtaining a maximum distance of approximately 500 m with parameters feasible for state-of-the-art experiments. Subsequently, we adapt entanglement distillation and entanglement swapping protocols to microwave technology in order to reduce the environment-induced entanglement degradation. The employed entanglement distillation helps to increase quantum correlations in the short-distance low-squeezing regime by up to 46%, and the reach of entanglement increases by 14% with entanglement swapping. Importantly, we compute the fidelity of a continuous-variable quantum teleportation protocol using open-air-distributed entanglement as a resource. Finally, we adapt this machinery to explore the limitations of quantum communication between satellites, where the impact of thermal noise is substantially reduced and diffraction losses are dominant.Item Propagating quantum microwaves : towards applications in communication and sensing(Institute of Physics Publishing, 2023-04) Casariego, Mateo; Zambrini Cruzeiro, Emmanuel; Gherardini, Stefano; Gonzalez-Raya, Tasio; André, Rui; Frazão, Gonçalo; Catto, Giacomo; Möttönen, Mikko; Datta, Debopam; Viisanen, Klaara; Govenius, Joonas; Prunnila, Mika; Tuominen, Kimmo; Reichert, Maximilian; Renger, Michael; Fedorov, Kirill G.; Deppe, Frank; van der Vliet, Harriet; Matthews, A. J.; Fernández, Yolanda; Assouly, R.; Dassonneville, R.; Huard, B.; Sanz, Mikel; Omar, Yasser; Department of Applied Physics; Quantum Computing and Devices; Centre of Excellence in Quantum Technology, QTF; Universidade de Lisboa; Instituto de Telecomunicações; Portuguese Quantum Institute (PQI); University of the Basque Country; VTT Technical Research Centre of Finland; University of Helsinki; Bayerische Akademie der Wissenschaften; Oxford Instruments Group Plc; TTI Norte, S.L.; École normale supérieure de LyonThe field of propagating quantum microwaves is a relatively new area of research that is receiving increased attention due to its promising technological applications, both in communication and sensing. While formally similar to quantum optics, some key elements required by the aim of having a controllable quantum microwave interface are still on an early stage of development. Here, we argue where and why a fully operative toolbox for propagating quantum microwaves will be needed, pointing to novel directions of research along the way: from microwave quantum key distribution to quantum radar, bath-system learning, or direct dark matter detection. The article therefore functions both as a review of the state-of-the-art, and as an illustration of the wide reach of applications the future of quantum microwaves will open.