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Student's colloquium | The Racah Institute of Physics

Student's colloquium

Date: 
Mon, 26/06/202312:00-13:30
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Location: 
Levin building, Lecture Hall No. 8

1.  "Chip-Integrated Vortex-Braiding" (Itai Keren)
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Superconducting vortices in p-wave superconductors, may host non-Abelian Majorana zero-modes. Braiding manipulations of such vortices are considered as operations in fault-tolerant quantum computation protocols. Here we present a vortex-control circuit, based on Nb superconducting loops residing below a NbSe2 layer. Imaging vortices using SQUID-on-Tip (SOT) microscopy demonstrates that well-placed Nb loops can position along designated axes with 40nm precision; they can shuttle vortices reliably within a 3 m range. Finally, we demonstrate a braiding operation where the system is initialized with two vortices, manipulated to revolve around each other and return to their original positions.


2. "From Multimode Nonlinear Optics to High-Dimensional Quantum Communications" (Kfir Sulimnay)

Quantum photonics often relies on nonlinear optics to generate photons, followed by reconfigurable linear optical networks for coherent control. In this talk, I will start by reviewing our study of multimode nonlinear optics in fibers [1,2], which also enabled our realization of an allfiber entangled photon pairs source [3]. These photons are spatially entangled in the eigenmodes of the multimode fiber, allowing for high-dimensional quantum communications. I will then present a couple of methods to coherently control such states. The first is achieved by multiplane light conversion based on a spatial light modulator [4], while the second is by employing a “Fiber piano” [5], a piezo-actuator array that deforms the multimode fiber. Finally, I will introduce a novel Quantum Key Distribution protocol that utilizes high-dimensional encoding to boost the secure key rate and its experimental implementation in the Israeli Quantum Key Distribution National Demonstrator [6]. 

[1] Kfir Sulimany, et al. Physical Review Letters 121.13 (2018): 133902. image can not be displayed
[2] Kfir Sulimany, et al. Optica 9.11 (2022): 1260-1267. 
[3] Kfir Sulimany, and Yaron Bromberg. npj Quantum Information 8.1 (2022): 1-5. 
[4] Ohad Lib, Kfir Sulimany, and Yaron Bromberg. Physical Review Applied 18.1 (2022): 014063. 
[5] Zohar Finkelstein, Kfir Sulimany, et al. APL Photonics (2023): 8 (3): 036110. 
[6] Kfir Sulimany, et al. arXiv preprint arXiv:2105.04733 (2021).