Leader: Dr. Tobias Schätz

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In the Emmy-Noether Research Group 'Quantum Simulations'  experiments are conducted to investigate whether an analog quantum computer can be created on the basis of an ion trap.

 

The spiritual father of the quantum computer, Richard Feynman, was particularly attracted to his idea because this new type of computer offers greater potential than conventional computers for simulating complex processes more effectively, thereby also enabling a better understanding of the events in nature based on these processes. When standard models can no longer describe complex multiparticle systems, it is necessary to simulate the systems taking into account quantum effects and mutual interactions. Any conventional computer (including conventional computers of the future) is entirely inadequate for such a task. A simple numerical example proves this: The computing power needed by a conventional computer rises exponentially with the particle number ‘N’ that is to be simulated. (If a particle can exist in two possible states, e.g. an electron in two directions of rotation, then the computing power needed rises by 2^N). For a still relatively modest system of 300 particles you would need 2³⁰⁰ numbers and therefore 2³⁰⁰ storage locations. This is equivalent to the estimated number of all the protons in our universe.

 

A wide spectrum of collective quantum phenomena will remain beyond the reach of deeper understanding without quantum computers and quantum simulators. These phenomena include both high-temperature supraconductivity and ferromagnetism and antiferromagnetism, as well as conductor-insulator transitions, supraconductivity and the Quantum Hall effect.

 

Our group investigates whether such quantum systems can be studied using what are for the time being still very simple quantum computers. The qubits in our quantum computer are represented by ions which, captured in an electromagnetic trap, are isolated from the environment almost without decoherence, cooled by laser to temperatures close to absolute zero and manipulated by laser. For example, we want to simulate the behaviour of a quantum magnet and investigate what is the meaning of a superposition of the north and south pole, or when several elementary quantum magnets are interlocked in the system, e.g. in quantum phase transitions. But it should also be possible to observe new – previously only predicted – quantum effects. Examples here are the first-ever proof of Unruh radiation (related to the Hawking radiation on the event horizon of black holes) and the quantum random walk (constructive and destructive overlaying of individual random paths result in interference effects).

 

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