A string of trapped ions at zero temperature exhibits a structural phase transition to a zigzag structure, tuned by reducing the transverse trap potential or the interparticle distance. The transition is driven by transverse, short wavelength vibrational modes. We argue that this is a quantum phase transition, which can be experimentally realized and probed. Indeed, by means of a mapping to the Ising model in a transverse field, we estimate the quantum critical point in terms of the system parameters, and find a finite, measurable deviation from the critical point predicted by the classical theory. A measurement procedure is suggested which can probe the effects of quantum fluctuations at criticality. These results can be extended to describe the transverse instability of ultracold polar molecules in a one-dimensional optical lattice.
|Journal||Physical Review Letters|
|State||Published - 4 Jan 2011|
Bibliographical noteFunding Information:
Acknowledgment: This study was partially funded by the Fundação para a Ciência e a Tecnologia (FCT) under research contract PTDC/AGR-AAM/70136/2006.