Particles in Harmony

Press release from

CRC DQ-mat focuses on the production and application of many-bodies

Explorers used to have it easier. They boarded a ship and sailed out into the world. Modern explorers work in laboratories and investigate whether what has been known for centuries about natural constants still holds true in the light of new evidence provided by modern metrology. Questions like these are addressed at the collaborative research centre Designed Quantum States of Matter (CRC 1227 DQ-mat). Apart from scientists from Leibniz Universität Hannover, further members are research teams from the PTB in Braunschweig and the Centre of Applied Space Technology and Microgravity (ZARM) at Universität Bremen.

The CRC is designed to run for twelve years. For the first four years, the Deutsche Forschungsgemeinschaft is funding the project to the amount of nearly ten million euros. Prof. Dr. Piet. O. Schmidt has taken on the function of the spokesperson.

"Our current understanding of physics is incomplete and could change fundamentally," says Prof. Dr. Klemens Hammerer, deputy spokesperson of the CRC. Innovative measuring methods currently being devised by the scientists will enable them to review natural constants and physical theories. Here, DQ-mat relies on two closely interconnected areas of research: Area A, devoted to quantum-correlated many-particle systems, and Area B, which uses quantum metrology to investigate fundamentals of physics. Both areas are perfectly in tune: Only through precise tests of single- and many-particle systems will it be possible to review physical laws.

Just like the pendulum on a clock, atoms can be made to "swing", or oscillate, in the lab. So far this has worked best only with isolated particles, i.e. it is much more difficult to make several identical atoms oscillate in harmony. The control of so-called quantum systems has, for example, led to the development of high-precision optical clocks that can measure time to 18 decimal places, or of matter-wave interferometers that exploit the wave properties of quantum particles.

For the first time, the scientists in Hannover now plan to produce many identical particles under controlled conditions, which will then oscillate in perfect harmony and be used to measure the earth''s gravitation field to a previously unobtained degree of precision. The basis for this is experiments that will later be carried out in the atom fountain in the HiTec.

To reach their goal, experts in particle physics, quantum information, quantum gases and metrology are working together to develop new methods to create, manipulate and detect quantum states. Investigating these states will lead to a deeper understanding of the quantum properties of many-particle systems. Mastering many-particle effects will provide one of the bases for improving the precision of quantum sensors. "The transition from single- to many-particle systems is a great step for metrology, opening up as yet unsuspected applications," says spokesperson Prof. Dr. Piet. O. Schmidt.

These novel ultra-precise measuring methods could lead to the review of fundamental assumptions in physics. These include questions of a possible change in natural constants, a violation of fundamental symmetries in physics, and the linking of quantum systems to gravitation. With their work, the scientists form one of the pillars for the planned Excellence Initiative application from the field of Quantum Physics.

Note to the editorial office

For further information please contact Prof. Dr. Klemens Hammerer, deputy spokesperson of CRC DQ-mat at Leibniz Universität Hannover, Telephone: +49 511 762 17056; E-Mail: