We experimentally characterize Hopf bifurcation phenomena at femtojoule energy scales in a multiatom cavity quantum electrodynamical (cavity QED) system and demonstrate how such behaviors can be exploited in the design of all-optical memory and modulation devices. The data are analyzed by using a semiclassical model that explicitly treats heterogeneous coupling of atoms to the cavity mode. Our results highlight the interest of cavity QED systems for ultralow power photonic signal processing as well as for fundamental studies of mesoscopic nonlinear dynamics.

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We present a numerical study of a MEMS-based design of a fiber cavity integrated with an ion trap system. Each fiber mirror is supported by a microactuator that controls the mirror's position in three dimensions. The mechanical stability is investigated by a feasibility analysis showing that the actuator offers a stable support of the fiber. The actuators move the fibers' positions continuously with a stroke of more than 10 µm, with mechanical resonance frequencies on the order of kHz. A calculation of the trapping potential shows that a separation between ion and fiber consistent with strong ion-cavity coupling is feasible. Our miniaturized ion-photon interface constitutes a viable approach to integrated hardware for quantum information. * These authors contributed equally to this work. † tracy.northup@uibk.ac.at ‡ dicho@snu.ac.kr Au electrodes on fused silica. A MEMS surface ion trap has smaller trap depth than a three-dimensional Paul trap [19] but has the advantage of a reconfigurable planar trapping geometry, along with extensive optical access for laser beams, as required for a large-scale ion trap quantum computer. In 2016, a MEMS trap called the High Optical Access 2.0 trap was developed by Sandia National Laboratory [20], which is widely used by many ion trap researchers today. Topics of active research include the question of how to reduce stray charge accumulation, e.g., on the trap sidewalls [21] or via in situ cleaning [22,23], and how to build increasingly sophisticated structures, e.g., junction traps [24,25] for ion transport, and two-or three-dimensional electrode arrays [26,27].MEMS-based ion traps have advantages in scalability and ease of fabrication, and they can also be easily integrated with other type of MEMS devices. MEMS techniques can also reduce the footprint of the optical cavity system [28,29], particularly for the mirror actuators. The replacement of standard high-finesse mirrors by fiber mirrors has already reduced the physical cavity volume significantly [30,31]; however, when commercial nanopositioning stages are used, they place significant space demands on the in-vacuum assembly. Here, we propose and investigate a novel design for a MEMS-based fibercavity system integrated with a surface ion trap. The fiber system is studied by analyzing the mechanical stability, resonances, and stroke. Furthermore, we calculate the trapping potential seen by the ions in order to discuss the prospects for strong ion-cavity coupling. II. BASIC CONCEPTThe main structure consists of a surface ion trap integrated with a MEMS-based fiber cavity system ( Fig. 1(a)). The starting point is a microfabricated chip, arXiv:1907.07594v1 [quant-ph]

Ions trapped in a quadrupole Paul trap have been considered one of the strong physical candidates to implement quantum information processing. This is due to their long coherence time and their capability to manipulate and detect individual quantum bits (qubits). In more recent years, microfabricated surface ion traps have received more attention for large-scale integrated qubit platforms. This paper presents a microfabrication methodology for ion traps using micro-electro-mechanical system (MEMS) technology, including the fabrication method for a 14 µm-thick dielectric layer and metal overhang structures atop the dielectric layer. In addition, an experimental procedure for trapping ytterbium (Yb) ions of isotope 174 (174Yb+) using 369.5 nm, 399 nm, and 935 nm diode lasers is described. These methodologies and procedures involve many scientific and engineering disciplines, and this paper first presents the detailed experimental procedures. The methods discussed in this paper can easily be extended to the trapping of Yb ions of isotope 171 (171Yb+) and to the manipulation of qubits.

Three-dimensional (3D) reconstruction of thick samples using superresolution fluorescence microscopy remains challenging due to high level of background noise and fast photobleaching of fluorescence probes. We develop superresolution fluorescence microscopy that can reconstruct 3D structures of thick samples with both high localization accuracy and no photobleaching problem. The background noise is reduced by optically sectioning the sample using line-scan confocal microscopy, and the photobleaching problem is overcome by using the DNA-PAINT (Point Accumulation for Imaging in Nanoscale Topography). As demonstrations, we take 3D superresolution images of microtubules of a whole cell, and two-color 3D images of microtubules and mitochondria. We also present superresolution images of chemical synapse of a mouse brain section at different z-positions ranging from 0 μm to 100 μm.Electronic supplementary materialThe online version of this article (10.1186/s13041-018-0361-z) contains supplementary material, which is available to authorized users.