QUROPE Quantum Information Processing and Communication in Europe

K. Singer (P18 JGUM), invited talk, Single ion implantation to the Heisenberg limit

K. Singer (P18 JGUM), invited talk, Ion Traps for Deterministic Ion Implantation and scalable quantum information

F. Schmidt-Kaler (P18 JGUM), talk, Scalable Quantum Information Processing with trapped ions (SQIP) - Recent results

F. Schmidt-Kaler (P18 JGUM), invited talk, Designing spin-spin interactions in cold ion crystals with magnetic gradients - from 1D to 2D

F. Schmidt-Kaler (P18 JGUM), invited talk, Designing Spin-Spin Interaction in cold Ion Crystals

G. Rempe (P3b MPQ), talk, Distribution of entanglement between atomic systems

D. Meschede (P6 UBONN), invited talk, Quantum Control of the Internal and External States of Single Atoms

We present a detailed theoretical and conceptual study of a planned experiment to excite Rydberg states of ions trapped in a Paul trap. The ultimate goal is to exploit the strong state-dependent interactions between Rydberg ions to implement quantum information processing protocols and simulate the dynamics of strongly interacting spin systems. We highlight the promise of this approach when combining the high degree of control and readout of quantum states in trapped ion crystals with the novel and fast gate schemes based on interacting giant Rydberg atomic dipole moments.

We propose to couple a trapped single electron to superconducting structures located at a variable distance from the electron. The electron is captured in a cryogenic Penning trap using electric fields and a static magnetic field in the tesla range. Measurements on the electron will allow investigating the properties of the superconductor such as vortex structure, damping and decoherence.

We use a single ion as an movable electric field sensor with accuracies on the order of a few V/m. For this, we compensate undesired static electric fields in a planar RF trap and characterize the static fields over an extended region along the trap axis. We observe a strong buildup of stray charges around the loading region on the trap resulting in an electric field of up to 1.3 kV/m at the ion position. We also find that the profile of the stray field remains constant over a time span of a few months.

We discuss the experimental feasibility of quantum simulation with trapped ion crystals, using magnetic field gradients. We describe a micro structured planar ion trap, which contains a central wire loop generating a strong magnetic gradient of about 20 T/m in an ion crystal held about 160 \mu m above the surface. On the theoretical side, we extend a proposal about spin-spin interactions via magnetic gradient induced coupling (MAGIC) [Johanning, et al, J. Phys. B: At. Mol. Opt. Phys. 42 (2009) 154009].

We exploit the geometry of a zig-zag cold-ion crystal in a linear trap to propose the quantum simulation of a paradigmatic model of long-ranged magnetic frustration. Such a quantum simulation would clarify the complex features of a rich phase diagram that presents ferromagnetic, dimerized antiferromagnetic, paramagnetic, and floating phases, together with previously unnoticed features that are hard to assess by numerics. We analyze in detail its experimental feasibility, and provide supporting numerical evidence on the basis of realistic parameters in current ion-trap technology.