April 15 2011

New article: Phys. Rev. A 83, 042319

Fast and robust quantum computation with ionic Wigner crystals
J. D. Baltrusch, A. Negretti, J. M. Taylor, T. Calarco.
Phys. Rev. A 83, 042319 (2011).

We present a detailed analysis of the modulated-carrier quantum phase gate implemented with Wigner crystals of ions confined in Penning traps. We elaborate on a recent scheme, proposed by two of the authors, to engineer two-body interactions between ions in such crystals. We analyze the situation in which the cyclotron (ωc) and the crystal rotation (ωr) frequencies do not fulfill the condition ωc=2ωr. It is shown that even in the presence of the magnetic field in the rotating frame the many-body (classical) Hamiltonian describing small oscillations from the ion equilibrium positions can be recast in canonical form. As a consequence, we are able to demonstrate that fast and robust two-qubit gates are achievable within the current experimental limitations. Moreover, we describe a realization of the state-dependent sign-changing dipole forces needed to realize the investigated quantum computing scheme.

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