Letter abstract

Nature Physics 4, 757 - 761 (2008)
Published online: 27 July 2008 | doi:10.1038/nphys1032

Subject Categories: Quantum physics | Atomic and molecular physics

Simulating a quantum magnet with trapped ions

A. Friedenauer1, H. Schmitz1, J. T. Glueckert, D. Porras & T. Schaetz


To gain deeper insight into the dynamics of complex quantum systems we need a quantum leap in computer simulations. We cannot translate quantum behaviour arising from superposition states or entanglement efficiently into the classical language of conventional computers. The solution to this problem, proposed in 1982 (ref. 1), is simulating the quantum behaviour of interest in a different quantum system where the interactions can be controlled and the outcome detected sufficiently well. Here we study the building blocks for simulating quantum spin Hamiltonians with trapped ions2. We experimentally simulate the adiabatic evolution of the smallest non-trivial spin system from paramagnetic into ferromagnetic order with a quantum magnetization for two spins of 98%. We prove that the transition is not driven by thermal fluctuations but is of quantum-mechanical origin (analogous to quantum fluctuations in quantum phase transitions3). We observe a final superposition state of the two degenerate spin configurations for the ferromagnetic order (|up arrowup arrowright fence+|down arrowdown arrowright fence), corresponding to deterministic entanglement achieved with 88% fidelity. This method should allow for scaling to a higher number of coupled spins2, enabling implementation of simulations that are intractable on conventional computers.

  1. Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Str. 1, D-85748 Garching, Germany
  2. These authors contributed equally to this work

Correspondence to: T. Schaetz e-mail: tschaetz@mpq.mpg.de


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