The alliance Quantum Valley Lower Saxony pools the expertise of more than 400 researchers intending to develop an ion trap quantum computer by 2025. Leibniz University Hannover holds a leading position in quantum technology and is therefore an essential partner within the alliance between LUH, TU Braunschweig, PTB, the Albert Einstein Institute and the recently established DLR Institute for Satellite Geodesy and Inertial Sensing.
Quantum computers are considered the next technical revolution due to quantum bits or qubits. While conventional computers perform calculations with the numbers zero and one, qubits can cover all intermediate stages. This is an enormous advantage in certain applications, such as in materials science, chemistry, pharmacology, mathematical optimisation or cryptography. Many issues in these areas cannot be solved with conventional computational architecture - even with computing power that might be available in the future - and can only be tackled with quantum computers. Artificial Intelligence too could benefit from the resources of a quantum computer.
However, such qubits are extremely fragile. As soon as their state is changed in a disordered manner, they can no longer be used as arithmetic units. The efficiency of a quantum computer is therefore determined by the error rate of the qubits. For this reason, the alliance Quantum Valley Lower Saxony intends to develop an ion trap quantum computer. With Professor Christian Ospelkaus (LUH) and Professor Piet Schmidt (PTB and LUH), the alliance comprises two of the world''s leading experts in quantum optics. Through the ion trap approach, the researchers aim to create stable qubits with an extremely low error rate not feasible to date. Qubits consist of free-floating ions isolated in a vacuum that are only addressed by microwave fields and lasers. The concept for the approach derives from metrology, in particular optical atomic clocks, where researchers also isolate individual ions in order to select data.
To date, quantum computers only exist in the form of huge and bulky laboratory set-ups. Even if it were possible to trap ions on a small chip, the rest of the laboratory would be packed with lasers, steering equipment and vacuum pumps - just for a few qubits. The quantum alliance intends to solve this issue by integrating as much as possible of this into one chip. This will enable them to apply scalable microfabrication procedures in order to realise chips for many qubits, which could be used for numerous quantum computing applications.
However, a low error rate in individual operations is another important prerequisite for operating quantum computers with an increasing number of qubits that are able to carry out long algorithms with an integrated error correction. For this, the quantum alliance has already developed a promising technology. Christian Ospelkaus and his research group use a specific method where high-precision operations are carried out via microwave conductors integrated into a chip https://www.uni-hannover.de/de/universitaet/aktuelles/presseinformationen/detail/news/robuste-rechenoperationen-fuer-den-quantencomputer/. The procedure was developed and characterised at LUH and PTB in collaboration with the Institute of Theoretical Physics.
Over the next five years, the alliance intends to realise a quantum computer with 50 qubits - an unprecedented level of precision and able to perform tasks with thousands of qubits without the necessity to change the initial set up.
Quantum physics as a key research area at LUH
Within the scope of the LUH key research area quantum optics and gravitational physics, more than 350 scientists conduct research in the field of quantum engineering, gravitational waves, precision measurements of space, time, light and matter as well as the development of laser systems and atomic clocks. Prof. Dr. Karsten Danzmann represents LUH as spokesperson of the Cluster of Excellence QuantumFrontiers. The researchers of the cluster focus on quantum metrological approaches for building a quantum computer. Thus, QuantumFrontiers became the nucleus of the new quantum alliance based in Lower Saxony.
As an interdisciplinary network, the QUEST Leibniz Research School brings together experts in physics, mathematics, engineering and natural sciences in order to use new technologies for pushing the boundaries of measurability - both on a small and a large scale. Furthermore, the Hannover Institute of Technology (HITec) provides an interdisciplinary research infrastructure for quantum technologies.
