In Research Theme II, the QSC will overcome the theoretical challenges in realizing a quantum internet and run key protocols. A quantum internet aims to create quantum entanglement between sender and receiver, enabling communication with security guarantees that cannot be achieved classically.
Aim
To overcome the theoretical challenges in enabling long distance quantum communication.
Theme leader
Prof. dr. Stephanie Wehner (QuTech, Delft University of Technology)
Overview and Motivation
A quantum network connects different quantum devices using quantum communication. This allows us to solve tasks that are provably impossible to achieve using classical information processing. Many applications for quantum networks need only very few qubits to obtain a genuine quantum advantage over any classical technology. A quantum network that connects many distant nodes is called a quantum internet. In the future, a quantum internet will operate in parallel to the internet of today, and ultimately allow quantum communication between any two points on earth.
Challenges
Challenge II.1: How can we exploit a quantum internet? A quantum internet allows the creation and manipulation of quantum entanglement over unprecedented distances. It will operate in parallel to the existing internet to enable new communication technologies that are impossible to achieve using classical communication.
Challenge II.2: What architecture allows quantum communication over continental distances? A quantum repeater can in principle enable quantum communication over any distance. Many proposals for quantum repeater designs exist, but it remains a grand challenge to design an architecture that can bridge very long distances in practice [San11, Rie15]. On a somewhat higher level, a good architecture for a quantum network should also allow us to generate entanglement between any two network nodes efficiently. The latter is crucial for network based quantum computers at short distances, as well.
Challenge II.3: What is the best way to correct errors in the storage and transmission of quantum information? Quantum error-correction allows us to protect entanglement from noise. To realize a quantum network, it will be essential to design good quantum error-correcting schemes that can take advantage of the specific properties and imperfections of small few-qubit quantum devices.
We will design and analyze quantum error-correcting schemes, even if the encoding and decoding procedures themselves are imperfect. At the same time, we will determine the limits of quantum error-correction for particular quantum devices and communication channels, to guide the design of quantum repeater architectures
Methods
Develop new quantum network protocols
We will build on our expertise in the theory of quantum communication complexity, which has recently found its first implementation. Here, the savings that quantum gives us are not in time, as is the case for quantum computation, but in the amount of qubits communicated. We investigate how the notion of quantum communication complexity can be exploited when each network node can operate only on few qubits.