QIPC

Robustness of topologically protected edge states in quantum walk experiments with neutral atoms

Date: 
2016-05-11
Author(s): 

Thorsten Groh, Stefan Brakhane, Wolfgang Alt, Dieter Meschede, Janos Asbóth, Andrea Alberti

Reference: 

arXiv:1605.03633 [quant-ph]

Discrete-time quantum walks allow Floquet topological insulator materials to be explored using controllable systems such as ultracold atoms in optical lattices. By numerical simulations, we study the robustness of topologically protected edge states in the presence of temporal disorder in one- and two-dimensional discrete-time quantum walks. We also develop a simple analytical model to gain further insight into the robustness of these edge states against either spin or spatial dephasing.

Super-resolution microscopy of single atoms in optical lattices

Date: 
2016-05-06
Author(s): 

Andrea Alberti, Carsten Robens, Wolfgang Alt, Stefan Brakhane, Michał Karski, René Reimann, Artur Widera and Dieter Meschede

Reference: 

New J. Phys. 18, 053010 (2016)

We report on image processing techniques and experimental procedures to determine the lattice-site positions of single atoms in an optical lattice with high reliability, even for limited acquisition time or optical resolution. Determining the positions of atoms beyond the diffraction limit relies on parametric deconvolution in close analogy to methods employed in super-resolution microscopy. We develop a deconvolution method that makes effective use of the prior knowledge of the optical transfer function, noise properties, and discreteness of the optical lattice.

High Finesse Fiber Fabry-Perot Cavities: Stabilization and Mode Matching Analysis

Date: 
2016-03-10
Author(s): 

J. Gallego, S. Ghosh, S. K. Alavi, W. Alt, M. Martinez-Dorantes, D. Meschede and L. Ratschbacher

Reference: 

Applied Physics B 122, 47 (2016)

Fiber Fabry-Perot cavities, formed by micro-machined mirrors on the end-facets of optical fibers, are used in an increasing number of technical and scientific applications, where they typically require precise stabilization of their optical resonances. Here, we study two different approaches to construct fiber Fabry-Perot resonators and stabilize their length for experiments in cavity quantum electrodynamics with neutral atoms.

Ultra-low birefringence dodecagonal vacuum glass cell

Date: 
2015-12-21
Author(s): 

Stefan Brakhane, Wolfgang Alt, Dieter Meschede, Carsten Robens, Geol Moon, and Andrea Alberti

Reference: 

Rev. Sci. Instrum. 86, 126108 (2015)

We report on an ultra-low birefringence dodecagonal glass cell for ultra-high vacuum applications.

Quantum Walks With Neutral Atoms: Quantum Interference Effects of One and Two Particles

Date: 
2015-11-11
Author(s): 

Carsten Robens, Stefan Brakhane, Dieter Meschede, Andrea Alberti

Reference: 

Proceedings of the XXII International Conference ICOLS (2015)

We report on the state of the art of quantum walk experiments with neutral atoms in state-dependent optical lattices. We demonstrate a novel state-dependent transport technique enabling the control of two spin-selective sublattices in a fully independent fashion. This transport technique allowed us to carry out a test of single-particle quantum interference based on the violation of the Leggett-Garg inequality and, more recently, to probe two-particle quantum interference effects with neutral atoms cooled into the motional ground state.

Quantum Gases and Quantum Coherence BEC2016

Date: 
2016-08-31 - 2016-09-03
Registration deadline: 
2016-06-30 (All day)
Place: 
Salerno
Website: 

bec2016.physics.unisa.it/

Interference and dynamics of light from a distance-controlled atom pair in an optical cavity

Date: 
2016-02-29
Author(s): 

Andreas Neuzner, Matthias Körber, Olivier Morin, Stephan Ritter, Gerhard Rempe

Reference: 

Nature Photonics 10, 303 (2016)

Interference is central to quantum physics and occurs when indistinguishable paths exist, as in a double-slit experiment. Replacing the two slits with single atoms introduces optical nonlinearities for which non-trivial interference phenomena are predicted. Their observation, however, has been hampered by difficulties in preparing the required atomic distribution, controlling the optical phases and detecting the faint light.

An integrated quantum repeater at telecom wavelength with single atoms in optical fiber cavities

Date: 
2016-03-10
Author(s): 

Manuel Uphoff, Manuel Brekenfeld, Gerhard Rempe, Stephan Ritter

Reference: 

Appl. Phys. B 122, 46 (2016)

Quantum repeaters promise to enable quantum networks over global distances by circumventing the exponential decrease in success probability inherent in direct photon transmission. We propose a realistic, functionally integrated quantum-repeater implementation based on single atoms in optical cavities. Entanglement is directly generated between the single-atom quantum memory and a photon at telecom wavelength. The latter is collected with high efficiency and adjustable temporal and spectral properties into a spatially well-defined cavity mode.

Cavity-based quantum networks with single atoms and optical photons

Date: 
2015-12-01
Author(s): 

Andreas Reiserer, Gerhard Rempe

Reference: 

Rev. Mod. Phys. 87, 1379 (2015)

Distributed quantum networks will allow users to perform tasks and to interact in ways which are not possible with present-day technology. Their implementation is a key challenge for quantum science and requires the development of stationary quantum nodes that can send and receive as well as store and process quantum information locally. The nodes are connected by quantum channels for flying information carriers, i.e., photons. These channels serve both to directly exchange quantum information between nodes and to distribute entanglement over the whole network.

Breakdown of atomic hyperfine coupling in a deep optical-dipole trap

Date: 
2015-11-18
Author(s): 

Andreas Neuzner, Matthias Körber, Stephan Dürr, Gerhard Rempe, Stephan Ritter

Reference: 

Phys. Rev. A 92, 053842 (2015)

We experimentally study the breakdown of hyperfine coupling for an atom in a deep optical-dipole trap. One-color laser spectroscopy is performed at the resonance lines of a single 87Rb atom for a trap wavelength of 1064 nm. Evidence of hyperfine breakdown comes from three observations, namely, a nonlinear dependence of the transition frequencies on the trap intensity, a splitting of lines which are degenerate for small intensities, and the ability to drive transitions which would be forbidden by selection rules in the absence of hyperfine breakdown.

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