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Humboldt-Universität zu Berlin - Mathematisch-Naturwissen­schaft­liche Fakultät - Nanooptik

Integrierte Mikroresonator-stabilisierte Lichtquellen für die (Quanten-)metrologie (iMiLQ)


Staff members:  Oliver Neitzke, Florian Böhm
Collaborators: Ferdinand-Braun-Institut (FBH)
Brilliance Fab Berlin GmbH (BFB)
Picoquant GmbH (PiQ)


Fundings through:



Efficient and bright solid-state single photon sources are are of particular interest in order to build quantum information devices and to perform quantum cryptography experiments. Defect centers in diamond, most prominent the nitrogen-vacancy (NV) center, have been proven to be stable and bright single photon emitters, even at room temperature. The efficient and small-scale coupling of such a single emitter to a photonic device or a fiber network is an essential requirement to build complex quantum systems on a small scale without the need for bulky objectives.


In this joint project with the Ferdinand-Braun-Institut (FBH) and the two industrial partners Brilliance Fab Berlin GmbH (BFB) and Picoquant GmbH (PiQ), we are investigating a monolithic realized resonant single photon source. Starting point is research of the prior joint project AdMiRe (Advanced Micro-Resonators), which established a novel technology basis for SiO 2 microresonators, processed via standard semiconductor technology [Fig 1].

In the new enhanced system we want to integrate a SiO 2 waveguide and a toroidal microresonator on a chip and deterministic couple a single photon emitting diamond nanocrystal to the system via nanomanipulation. By resonant excitation of the defect center one can obtain a very narrow spectral emission window of emitted photons. The proposed system is capable of separation of excitation light from emitted photons to obtain a maximum amount of filtered single photons, even at resonant excitation. Additionally, due to the multiple ports of the device, analysis and stabilisation of the single-photon source could be achieved by fast statistical evaluation of the emitters single-photon
emission, measured with single-photon detectors.

This novel, monolithic single-photon source could be used as a source for new concepts in quantum information, quantum cryptography and radiometry. In particular it is interesting for applications in handheld or satellite systems due to its small size and simplicity.

Fig. 1: Scanning electron micrograph of a silica microdisk with 25um radius, developed during AdMiRe. Fig. 2: Optical microscope image of evanescently coupled light into a microdisc resonator via a tapered optical fibre.


Fig. 3: Schematic of the proposed system with an integrated SiO2 waveguide and toroidal microresonator on a chip and a coupled single photon emitter (e.g. diamond nanocrystal with a defect center).


Dieses Projekt wurde kofinanziert durch den Europäischen Fonds für regionale Entwicklung (EFRE).