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Details of Grant 

EPSRC Reference: EP/X039439/1
Title: Towards The Quantum Internet: Interconnecting Quantum Networks
Principal Investigator: Joshi, Dr S K
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Rudjer Boskovic Institute
Department: Electrical and Electronic Engineering
Organisation: University of Bristol
Scheme: New Investigator Award
Starts: 01 March 2024 Ends: 31 August 2026 Value (£): 307,445
EPSRC Research Topic Classifications:
Optical Communications Optical Devices & Subsystems
Quantum Optics & Information
EPSRC Industrial Sector Classifications:
Communications Information Technologies
Related Grants:
Panel History:
Panel DatePanel NameOutcome
25 Sep 2023 EPSRC ICT Prioritisation Panel Sept 2023 Announced
Summary on Grant Application Form
Quantum technologies are rapidly changing the way we process information - Quantum Communication offers mathematically perfect security, Quantum Sensors can be more precise and sensitive than their classical counterparts and Quantum Computing can go beyond the best possible supercomputers. To make the best of all these technologies, they need to be connected together in much the same way classical devices are connected by the internet. This vision - the quantum internet cannot just use the classical binary encoding of data, but must exploit quantum entanglement. Entanglement is the fundamental resource that most quantum devices use akin to the zeros and ones at the core of all digital technologies. Naturally the quantum internet must allow end to end distribution of entanglement.

Distributing entanglement is incredibly difficult because it can so easily be irrecoverably destroyed by loss, noise or any interaction with the environment. Around the world there are extensive efforts to develop the necessary technologies form a top down perspective. E.g. Satellites for long distance quantum communication, quantum repeaters and quantum memories, to enable efficient teleportation and storage of entanglement, etc. In this proposal I would like to consider a bottom up approach. Starting with the technology (I invented) to create a small network of say eight users in the quantum version of a local area network (Q-LAN), I want to be able to connect multiple copies of this Q-LAN together to create a seamless larger quantum network that overcomes the limitations of a Q-LAN. A useful analogy is to consider your Wi-Fi network and how it then connects to a larger network of networks.

Here I propose to build a second Q-LAN in Bristol and interconnect it with the existing quantum network test bed, that I have already built, to test 3 different novel methods of linking quantum networks:

The first and simplest approach is to link the quantum networks together with a trusted node. A trusted node, does not preserve quantum information but converts it classical and back again. This means that entanglement is not preserved and it limits the applications to tasks like quantum communication. Nevertheless, this will be an important step in identifying problems and bottlenecks for network traffic.

The second way will exploit the dynamically reconfigurable nature of my existing Q-LAN technology and study if this can be used to interlink different quantum networks. A Q-LAN works by assigning each user one half of an entangled state (differentiated by wavelength) and allowing the users to perform joint operations on the entire entangled state to complete quantum information processing tasks. Using two Q-LANs I propose to allow users to share one half of an entangled state from either the original or the new network. If this is successful, I will be able to overcome the limitation on the number of users in a single Q-LAN and create a larger network. If this method proves scalable, it could be an excellent candidate for the quantum internet of the future.

The third approach is to use quantum teleportation to "teleport" the entangled state from one Q-LAN to another, this has all the advantages of the previous method and can also be used to reduce the effects of loss.

Quantum networks is an emerging field and each of these three steps constitute a unique and novel approach that has not been tried before. The key-enabling technology which will ensure that this research is both ground-breaking and successful is the wavelength multiplexed Q-LAN method I invented. In addition to this, I am also working on top down approaches like satellite based quantum communication. This new investigator award, will help me establish a new world leading research group uniquely capable of combining top down and bottom up approaches to realise my ambitions of building the quantum internet.

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Organisation Website: http://www.bris.ac.uk