QUIE2T Quantum Information Entanglement-Enabled Technologies

Professor Klaus Mølmer receives the Villum Kann Rasmussen Annual Award for Technical and Scientific Research.

For further details, please visit the following link:

http://www.au.dk/en/about/news/single/artikel/kvantemekanikkens-stemme-faar-danmarks-stoerste-forskerpris/

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. 

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 theoretically investigate the properties of a double-well bosonic Josephson junction coupled to a single trapped ion. We find that the coupling between the wells can be controlled by the internal state of the ion, which can be used for studying mesoscopic entanglement between the two systems and to measure their interaction with high precision. As a particular example we consider a small $^{87}$Rb Bose-Einstein condensate controlled by a single $^{171}$Yb$^+$ ion.

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