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. 

• Light-based qubits

The Solid State and High Dimensional Quantum Optics research group led by Wolfgang Löffler studies light-based qubits. The group works on highly sensitive light detectors and techniques to tailor photons to precise specifications.

• Quantum networks

To transport quantum information, for example between quantum computers, quantum networks are needed. These networks form a kind of quantum version of the internet. The Quantum Detection research group led by Michiel de Dood is investigating extremely sensitive single-photon sensors that can detect single photons with high certainty.

• Quantum gates

Linking quantum networks to quantum computers requires quantum gates, that capture quantum information from a photon and transfer it to another type of qubit. Quantum emitters are also needed to do just the opposite: transfer quantum information from a qubit to a photon. Martin van Exter's Quantum Optics and Light-Matter Interaction group investigates such quantum gates. For example, by trapping a photon in a cavity, a kind of microscopic mirror palace in which light bounces around continuously.

• Research at extremely low temperatures

Quantum sensing is all about extremely sensitive measurements. Some of these are done at extremely low temperatures. The research groups Quantum Optics and Quantum Information (Dirk Bouwmeester) and Microscopy and Quantum Mechanics at milliKelvin Temperatures (Tjerk Oosterkamp) specialise in increasing the sensitivity of such quantum measurements, focusing on optical systems and magnetic systems respectively.

• Local quantum companies

There are several companies in Leiden that work on quantum. Onnes Technologies, Leiden Spin Imaging and Leiden Probe Microscopy work closely with the low-temperature research groups. Leiden Cryogenics supplies the crucial cryostats.