arXiv subjects

Sakshi Sharma

Publications and source records attributed to Sakshi Sharma.

3 recordsLinked to original sources

arXiv2024

Ad-hoc hybrid-heterogeneous metropolitan-range quantum key distribution network

This paper presents the development and implementation of a versatile ad-hoc metropolitan-range Quantum Key Distribution (QKD) network. The approach presented integrates various types of physical channels and QKD protocols, and a mix of trusted and untrusted nodes. Unlike conventional QKD networks that predominantly depend on either fiber-based or free-space optical (FSO) links, the testbed presented amalgamates FSO and fiber-based links, thereby overcoming some inherent limitations. Various network deployment strategies have been considered, including permanent infrastructure and provisional ad-hoc links to eradicate coverage gaps. Furthermore, the ability to rapidly establish a network using portable FSO terminals and to investigate diverse link topologies is demonstrated. The study also showcases the successful establishment of a quantum-secured link to a cloud server.

quant-ph↗

arXiv2023

Towards metropolitan free-space quantum networks

Quantum communication has seen rapid progress towards practical large-scale networks, with quantum key distribution (QKD) spearheading this development. While fibre based systems have been shown to be well suited for metropolitan scales, suitable fibre infrastructure may not always be in place. Here, we make the case for an entanglement-based free-space quantum network as a practical and efficient alternative for metropolitan applications. We developed a deployable free space QKD system and demonstrated its use in realistic scenarios. For a representative 1.7-km free-space link, we showcase its ad hoc deployability and achieve secure key rates of up to 5.7 kbps, with 2.5 kbps in direct noon sunlight. By extrapolating experimental data, we show that kbps key rates are achievable even for 10-km distances and multi-user scenarios. We anticipate that our work will establish free space networks as a viable solution for metropolitan applications and an indispensable complementary building block in the future global quantum internet.

quant-ph↗

arXiv2022

Clock synchronization with correlated photons

Event synchronisation is a ubiquitous task, with applications ranging from 5G technology to industrial automation and smart power grids. The emergence of quantum communication networks will further increase the demand for precise synchronization in the optical and electronic domains, which implies significant resource overhead, such as the requirement for ultrastable clocks or additional synchronization lasers. Here we show how temporal correlations of energy-time entangled photons may be harnessed for synchronisation in quantum networks. We achieve stable synchronisation jitter <68 ps with as few as 44 correlated detection events per 100-ms data package and demonstrate feasibility in realistic emulated high-loss link scenarios, including atmospheric turbulence. In contrast to previous work, this is accomplished without any external timing reference and only simple crystal oscillators. Our approach replaces the optical and electronic transmission of timing signals with classical communication and computer-aided postprocessing. It can be easily integrated into a wide range of quantum communication networks and could pave the way to future applications in entanglement-based secure time transmission.

quant-ph↗