Project »QUILT« – Quantum Methods for Advanced Imaging Solutions

The field »Quantum Imaging« focuses on the use of non-classical light states for new methods in imaging and spectroscopy. The main objective of the Fraunhofer »Lighthouse Project« QUILT is to make spectral and image information from the wavelength ranges terahertz, mid-infrared and ultraviolet measurable with silicon-based detectors and cameras using entangled photon pairs with strong wavelength spreading.

Infrared spectroscopy with visible photons

One of the most important methods for the chemical analysis of molecules and organic compounds is infrared spectroscopy. This method usually requires an infrared light source and an infrared detector. However, compared to detectors for the visible or near-infrared spectral range, infrared detectors have a higher dark noise, are technologically more complex and expensive.

Using a nonlinear interferometer, we can detect the spectral information from the mid-infrared with visible light. For this purpose, entangled photon pairs are generated, in which one of the light quanta is in the visible spectral range and one in the mid-infrared range. In an interferometer setup, the light beams are superimposed in such a way that the interaction of the infrared photons with an investigated sample can be measured in the interference pattern of the visible photons. This is only possible because of the quantum mechanical nature of the entangled photons.

From basic research to application demonstration

Within the »QUILT« project, Fraunhofer IPM develops quantum spectrometers in the mid-infrared (3-5 µm) and the so-called fingerprint range (8-12 µm). In recent work, we demonstrated a novel method for infrared spectroscopy with visible light in analogy to the measuring principle of a Fourier transform infrared spectrometer.

At Fraunhofer IPM we benefit from our expertise in the field of nonlinear optical materials, which serve as a source for the entangled photons. During system development, our many years of experience in spectroscopic analysis help us incorporate the requirements of measurement technology in realistic application scenarios.

© K.-U. Wudtke / Fraunhofer IPM
Quantum light:
A green pump laser generates entangled photon pairs from infrared and visible light quanta (red circle on the screen) in a nonlinear optical crystal.

Project finance

The project »QUILT« is being funded within the »Lighthouse Projects« initiative by the Fraunhofer-Gesellschaft.

Project partners

  • Fraunhofer Institute for Applied Optics and Precision Engineering IOF
  • Fraunhofer Institute for Laser Technology ILT
  • Fraunhofer Institute for Microelectronic Circuits and Systems IMS
  • Fraunhofer Institute of Optronics, System Technologies and Image Exploitation IOSB
  • Fraunhofer Institute for Physical Measurement Techniques IPM
  • Fraunhofer Institute for Industrial Mathematics ITWM

External partners

The »QUILT« consortium cooperates with two of the world’s leading institutes in the field of quantum technology:

  • Institute for Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences
  • Max Planck Institute for the Science of Light, Erlangen

Project duration

10/2017 until 06/2021

Further information

Scientific publication

Quantum FTIR: Editor’s pick in Optics Express


Editor's Picks serve to highlight articles with excellent scientific quality which are representative of the work taking place in a specific field.




Expertise in sensor technology

Quantum sensing at Fraunhofer IPM

Applied research in quantum optics

Fraunhofer Lighthouse Project »QUILT«


Research in quantum technology has achieved a number of scientific breakthroughs in recent years. Scientists, politicians and business people are talking about a »second quantum revolution« in which quantum technology will play a role as a key technology of the modern information society. While the first generation of quantum technologies was based on the use of collective quantum properties of countless particles, today individual quanta can be prepared, manipulated, transmitted and measured in their entanglement and superposition states. Individual quantum systems are the foundation for disruptive changes in a wide range of applications: from industrial production to medicine and biotechnology, automotive engineering, information & communication, aerospace and science. Moreover, quantum optical systems will also play a role in emerging markets such as environmental analysis or civil security and information security.

What is quantum sensor technology?

Quantum sensor technology is the measurement of physical or chemical properties of a material or environment using the special characteristics of isolated quanta. Entangled photons or isolated atoms can be used as sensors, which are clearly superior to classical sensors in terms of sensitivity and resolution.