Research reports: Technologies for Quantum Computing

Recent developments for quantum computers at Fraunhofer IOF

Fraunhofer IOF offers a wide range of components and systems in the field of quantum hardware. In addition, our experts develop new customized components and systems on behalf of our customers from industry and research. Our offer ranges from the design to the integration of innovative quantum optical solutions for the fields of application computing, communication, imaging, and sensing.


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Quantum hardware


Below you will find interesting facts and research reports about our latest developments in quantum computing:

Laser-based addressing optics for an ion trap of a quantum computer.
© Fraunhofer IOF
Laser-based addressing optics for an ion trap of the next generation quantum computer, which is being developed within the AQTION project.

Interesting to know

What is a quantum computer ?

A quantum computer is a processor that - unlike a classical computer - is based on the interactions of quantum mechanical states.

Conventional computers use bits as the smallest possible memory units. Quantum computers, in contrast, work with so-called “QuBits” or “quantum bits”.

Fields of application: e.g., pharmaceutical research, communication security, logistics incl. traffic optimization, material optimization, simulation for natural sciences.

How does a quantum computer work?

A quantum computer uses so-called “quantum effects” for more computing power. One such effect can be the entanglement of photons. For one thing, this entanglement allows the computer's “digital reasoning”, which is classically limited to two states - namely zero and one - to be extended to include a concept of continuous functions. This means that QuBits - unlike bits - can assume multiple states (more than zero and one) at the same time.

Furthermore, the computing capacity increases exponentially with the number of QuBits. Quantum computers thus create the possibility of finding solutions to problems that still seem unsolvable to us today.


The first quantum computer in Germany is located in Baden-Württemberg. Fraunhofer and IBM have presented it to the public in 2021. The quantum computer is available to companies and research organizations to develop quantum algorithms as well as to build know-how.

Our technology for a step into the future: 

Addressing optics for ion and atom trap based quantum computers.

Close-up of the laser-based addressing optics for quantum computers.
© Fraunhofer IOF
Close-up of the laser-based addressing optics for an ion trap of the next generation quantum computer, which is being developed within the AQTION project.

Realization of a scalable quantum computer

In the project "Advanced quantum computing with trapped ions" (AQTION), a component of the quantum flagship program of the EU, a scalable ion trap-based quantum computer was realized. This was being built and deployed at the University of Innsbruck, the consortium leader of the AQTION network.

In the long term, great things are planned within the framework of the AQTION alliance: The goal of the project partners is to build a powerful quantum computer suitable for industrial use and to significantly advance applied research on quantum computing in Germany.

Laboratory setup of the addressing optics.
© Fraunhofer IOF
Fig. 1: Laboratory setup of the addressing optics.

Ion-based quantum computer

The quantum computer developed in the AQTION research project is based on so-called "ion QuBits". The system uses stored ions as QuBits, which can be held in electromagnetic traps and controlled within them with laser beams. For this purpose, a laser-optical setup was realized at Fraunhofer IOF, which enables the manipulation of ions in the ion trap for quantum computers.


Manipulate and measure the state of the ions

Within the AQTION quantum computer, the quantum bits (Qbits) are represented by Ca+-ions, which are confined within a Paul trap. In order to prepare the quantum states and execute calculations at the quantum gate, different laser wavelengths are used. This includes to illuminate single ions with a laser spot of a wavelength of 729 nm (Fig. 3). The result of the calculations is "read out" from the status of the ions that are arranged in a linear chain within the trap. The status of the ion at the time of the measurement becomes apparent by checking whether a fluorescence signal is emitted or not.

Construction drawing 19" rack with ion trap and folded addressing optics.
© Fraunhofer IOF
Fig. 2: Construction drawing 19" rack with ion trap and folded addressing optics.

Accurate addressing of the ions

Reliable addressing of the ions that are spaced by 3 microns approximately in the center of the trap requires diffraction-limited spots, on one hand, and on the other a means of tracking the spots along the trap axis with sub-micron accuracy. To this end, a particular optomechanical unit was developed where in a special solid-state-joint configuration piezo-actuators induce a linear movement of micro-prisms, figure 1. The optomechanical unit transforms the fixed array of input-fibers in a dynamically adjustable arrangement of sources. The additional optics ensure the demagnification of the source distances at the input down to the ion distances, as well as the appropriate spot sizes in the plane of the trap. In addition to a special objective, which is corrected for the wavelengths of the addressing beam and the fluorescence detection, gradient index and achromatic lenses are used.  

Visualization of the optics structure of the addressing unit for a quantum computer.
© Fraunhofer IOF
Fig.. 3: Visualization of the optics structure of the addressing unit for a quantum computer.

Miniaturization of the system

For the overall optical setup (Fig. 3), a multiple folding of the beam path (Fig. 1 (left) and Fig. 2) is required to ensure the potential for integration. To have the optimum focal length of the parabolic mirror – an essential component for the device principle (submitted as patent application) – this mirror is constructed by ultra-precision machining at Fraunhofer IOF.


Bernd Höfer, Felix Kraze, Peter Schreiber, Christoph Wächter, Uwe Zeitner

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