QUROPE Quantum Information Processing and Communication in Europe

We propose detecting the magnetic field gradient produced by the magnetic dipole moment of a single atom by using ions in an entangled state trapped a few μm from the dipole.

The accurate characterization of eigenmodes and eigenfrequencies of two-dimensional ion crystals provides the foundation for the use of such structures for quantum simulation purposes.

We realize fast transport of ions in a segmented microstructured Paul trap. The ion is shuttled over a distance of more than 104 times its ground state wave function size during only five motional cycles of the trap (280
m in 3:6
s). Starting from a ground-state-cooled ion, we find an optimized transport such that the energy increase is as low as 0:10
0:01 motional quanta. In addition, we demonstrate that quantum information stored in a spin-motion entangled state is preserved throughout the transport.

We theoretically investigate the properties of a double-well bosonic Josephson junction coupled to a single trapped ion.

In this article we discuss and compare different ways to engineer an interface between ultracold atoms

We measure the frequency dependence of the mechanical quality factor (Q) of SiN membrane oscillators and observe a resonant variation of Q by more than two orders of magnitude. The frequency of the fundamental mechanical mode is tuned reversibly by up to 40% through local heating with a laser. Several distinct resonances in Q are observed that can be explained by coupling to membrane frame modes. Away from the resonances, the background Q is independent of frequency and temperature in the measured range.

We have realized a hybrid optomechanical system by coupling ultracold atoms to a micromechanical membrane.

Mechanical resonators find widespread applications as precision force sensors, the most prominent example being the atomic force microscope (AFM).

We demonstrate a simple technique for microwave field imaging using alkali atoms in a vapor cell.

Long range Rydberg blockade interactions have the potential for efficient implementation of quantum gates between multiple atoms. Here we present and analyze a protocol for implementation of a $k$-atom controlled NOT (C$_k$NOT) neutral atom gate. This gate can be implemented using sequential or simultaneous addressing of the control atoms which requires only $2k+3$ or 5 Rydberg $\pi$ pulses respectively. A detailed error analysis relevant for implementations based on alkali atom Rydberg states is provided which shows that gate errors less than 10% are possible for $k=35$.