Hannover 2013 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 5: Quantum information: Atoms and ions I
Q 5.2: Talk
Monday, March 18, 2013, 11:15–11:30, E 214
Quantum quenches of ion Coulomb crystals across structural instabilities — •Jens D. Baltrusch1,2, Cecilia Cormick3, and Giovanna Morigi1 — 1Theoretische Quantenphysik, Universität des Saarlandes — 2Grup d’Optica, Universitat Autònoma de Barcelona — 3Institut für Theoretische Physik, Universität Ulm
We theoretically analyze the efficiency of a protocol for creating mesoscopic superpositions of ion chains, described in [Phys. Rev. A 84, 063821 (2011)], as a function of the temperature of the crystal. The protocol makes use of spin-dependent forces, so that a coherent superposition of the electronic states of one ion evolves into an entangled state between the chain’s internal and external degrees of freedom. Ion Coulomb crystals are well isolated from the external environment, and should therefore experience a coherent, unitary evolution, which follows the quench and generates a structural Schrödinger cat-like state. The initial temperature of the chain, however, introduces a statistical uncertainty in the final state. We characterize the quantum state of the crystal by means of the visibility of Ramsey interferometry performed on one ion of the chain [Phys. Rev. A 86, 032104 (2012)], and determine its decay as a function of the crystal’s initial temperature. This analysis allows one to determine the conditions on the chain’s initial state for performing the protocol.