QUROPE Quantum Information Processing and Communication in Europe

A recent PRL on the realization of a hybrid atom-optomechanical system involving AQUTE researchers in the University of Basel, received some attention, including a "Physics viewpoint" and an article in the January issue of the Physik Journal. 

The 2nd year AQUTE review meeting has been scheduled on the 20th of April, 2012, in Mainz. As usual by now, the review will happen within the cluster review meeting, that will run in Mainz from the 18th to the 20th of April, 2012, featuring the QIPC open day on the 19th.

We investigate the implementation of a controlled-Z gate on a pair of Rydberg atoms in spatially separated dipole traps where the joint excitation of both atoms into the Rydberg level is strongly suppressed (the Rydberg blockade). We follow the adiabatic gate scheme of Jaksch et al. [1], where the pair of atoms are coherently excited using lasers, and apply it to the experimental setup outlined in Ga\"etan et al. [2]. We apply optimisation to the experimental parameters to improve gate fidelity, and consider the impact of several experimental constraints on the gate success.

We numerically investigate the performance of atomic transport in optical microtraps via the so called spatial adiabatic passage technique. Our analysis is carried out by means of optimal control methods, which enable us to determine suitable transport control pulses. We investigate the ultimate limits of the optimal control in speeding up the transport process in a triple well configuration for both a single atomic wave packet and a Bose-Einstein condensate within a regime of experimental parameters achievable with current optical technology.

While solid-state devices offer naturally reliable hardware for modern classical computers, thus far quantum information processors resemble vacuum tube computers in being neither reliable nor scalable. Strongly correlated many body states stabilized in topologically ordered matter offer the possibility of naturally fault tolerant computing, but are both challenging to engineer and coherently control and cannot be easily adapted to different physical platforms.

We present a fault-tolerant (FT) semi-global control strategy for universal quantum computers. We show that an N-dimensional array of qubits where only (N−1)-dimensional addressing resolution is available is compatible with FT universal quantum computation. What is more, we show that measurements and individual control of qubits are required only at the boundaries of the FT computer. Our model alleviates the heavy physical conditions on current qubit candidates imposed by addressability requirements and represents an option for improving their scalability.

We study the single particle dynamics of a mobile non-Abelian anyon hopping around many pinned anyons on a surface, by modeling it with a discrete time quantum walk. During the evolution, the spatial degree of freedom of the mobile anyon becomes entangled with the fusion degrees of freedom of the collective system. Each quantum trajectory makes a closed braid on the world lines of the particles establishing a direct connection between statistical dynamics and quantum link invariants.

R. Nyman (P5 IMPERIAL), talk, An integrated photonic atom chip

B. Yuen (P5 IMPERIAL), poster, Measuring energy differences by BEC interferometry on a chip

J.P. Cotter (P5 IMPERIAL), poster, characteristics of integrated magneto-optical traps for atom chips

J. Garvie-Cook (P5 IMPERIAL), poster, An array of integrated atom-photon junctions

G. Lepert (P5 IMPERIAL), poster, Atoms and molecules in arrays of coupled cavities

E.A. Hinds (P5 IMPERIAL), talk, 5 Atomchips at Imperial

J. Hwang (P5 IMPERIAL), talk, Quantum nanophotonics with single molecules

R. Nyman (P5 IMPERIAL), talk, Cold atoms and integrated photonics for quantum information

E. A. Hinds (P5 IMPERIAL), talk, 5 Atomchips at Imperial