A neutral atom quantum register

We demonstrate the realization of a quantum register using a string of single neutral atoms which are trapped in an optical dipole trap. The atoms are selectively and coherently manipulated in a magnetic field gradient using microwave radiation. Our addressing scheme operates with a high spatial resolution and qubit rotations on individual atoms are performed with 99% contrast. In a final read-out operation we analyze each individual atomic state. Finally, we have measured the coherence time and identified the predominant dephasing mechanism for our register.Comment: 4 pages, 4 figure

Adiabatic Quantum State Manipulation of Single Trapped Atoms

We use microwave induced adiabatic passages for selective spin flips within a string of optically trapped individual neutral Cs atoms. We position-dependently shift the atomic transition frequency with a magnetic field gradient. To flip the spin of a selected atom, we optically measure its position and sweep the microwave frequency across its respective resonance frequency. We analyze the addressing resolution and the experimental robustness of this scheme. Furthermore, we show that adiabatic spin flips can also be induced with a fixed microwave frequency by deterministically transporting the atoms across the position of resonance.Comment: 4 pages, 4 figure

Precision preparation of strings of trapped neutral atoms

We have recently demonstrated the creation of regular strings of neutral caesium atoms in a standing wave optical dipole trap using optical tweezers [Y. Miroshnychenko et al., Nature, in press (2006)]. The rearrangement is realized atom-by-atom, extracting an atom and re-inserting it at the desired position with sub-micrometer resolution. We describe our experimental setup and present detailed measurements as well as simple analytical models for the resolution of the extraction process, for the precision of the insertion, and for heating processes. We compare two different methods of insertion, one of which permits the placement of two atoms into one optical micropotential. The theoretical models largely explain our experimental results and allow us to identify the main limiting factors for the precision and efficiency of the manipulations. Strategies for future improvements are discussed.Comment: 25 pages, 18 figure

A case of osteomalacia in human skeletal remains from St Hripsime Church (Horom, Armenia)

In this study, we investigated the remains of an individual that were recovered during cleansing work of the Church of St Hripsime. Macroscopic and X-Ray inspections yielded pathological criteria which indicated osteomalacic origin. The findings of the study suggest that the individual who lived in the Late Medieval period may have gone through multiple episodes of vitamin D deficiency. Vitamin D deficiency as an effect of deficient exposure to sunlight (in particular, in rural individuals who lived in underground houses) and nourishment deficiency could be described as the main causes leading to osteomalacia in Armenia

Coherence properties and quantum state transportation in an optical conveyor belt

We have prepared and detected quantum coherences with long dephasing times at the level of single trapped cesium atoms. Controlled transport by an "optical conveyor belt" over macroscopic distances preserves the atomic coherence with slight reduction of coherence time. The limiting dephasing effects are experimentally identified and are of technical rather than fundamental nature. We present an analytical model of the reversible and irreversible dephasing mechanisms. Coherent quantum bit operations along with quantum state transport open the route towards a "quantum shift register" of individual neutral atoms.Comment: 4 pages, 3 figure

Continued imaging of the transport of a single neutral atom

We have continuously imaged the controlled motion of a single atom as well as of a small number of distinguishable atoms with observation times exceeding one minute. The Cesium atoms are confined to potential wells of a standing wave optical dipole trap which allows to transport them over macroscopic distances. The atoms are imaged by an intensified CCD camera, and spatial resolution near the diffraction limit is obtained

Quantum jumps and spin dynamics of interacting atoms in a strongly coupled atom-cavity system

We experimentally investigate the spin dynamics of one and two neutral atoms strongly coupled to a high finesse optical cavity. We observe quantum jumps between hyperfine ground states of a single atom. The interaction-induced normal mode splitting of the atom-cavity system is measured via the atomic excitation. Moreover, we observe evidence for conditional dynamics of two atoms simultaneously coupled to the cavity mode. Our results point towards the realization of measurement-induced entanglement schemes for neutral atoms in optical cavities.Comment: 4 pages, 4 figures, published versio

The probable evidence of leprosy in a male individual unearthed in medieval Armenia (Angeghakot)

The objective of this study is to present the paleopathological lesions relevant to the discussion of the differential diagnosis of leprosy. Macroscopic, histological and X-ray observation of the bones and scrutiny of lesions according to the paleopathological literature allowed the identification of a probable case of leprosy in an adult male from Angeghakot (Early Middle Age, skeleton 4). The skeleton of a male (50–55 years) revealed several bony changes indicative of leprosy with clear rhino-maxillary syndrome. There is a scarcity of information in the osteoarchaeological literature of leprosy in ancient Armenia. The significance of this case is that it adds to an understanding of the history of the disease in Armenia and to the data set necessary to understand the epidemiological dynamics in the South Caucasus during the Early Middle Ages