Within Quantum Leiden, several groups conduct research into quantum networks and quantum sensing, for example, on quantum sensors that can detect individual photons. This makes it possible to perform very sensitive measurements.

• Quantum sensing technology

Several experimental groups employ coherent quantum systems to achieve specific sensing needs. Such quantum sensors can characterize complex quantum devices, illuminate poorly understood phases of matter, sense surface spin fluctuations, or even sense the effects occurring on the interface between quantum physics and gravity. Examples of quantum sensors employed at the Leiden hub are magnetic force microscopy (nano-MRI), Scanning Superconducting Quantum Interference Device (SQUID) magnetic sensing (including SQUID-on-tip), and levitated particles for optomechanical force sensing.

• Quantum network development

We also study single photon generation and detection as well as entangled photon sources. We explore use of the photons for several applications, for instance for quantum networks: from quantum cryptography including novel protocols exploring multiple physical principles, to all-photonic quantum repeaters. These photons are also crucial for optical quantum computation, where entangled clusters and graph states would be a game-changing resource for measurement-based quantum computation. Examples of photon sources studied are 2D Van der Waals materials and semiconductor quantum dots in optical microcavities. Within Quantum Leiden, several groups conduct research into quantum networks and quantum sensing, for example, on quantum sensors that can detect individual photons. This makes it possible to perform sensitive measurements in laboratories. Photons can also be used in the development of even more modern quantum computers, in which light is the information carrier. These light particles are less sensitive to disturbances than the types currently being developed.