Quantum Technologies Accelerated by Ultrahigh Vacuum Technologies

Blanchard, Philippe, Erwin Brüning

Yuri Yosuke, Hosaka Koichi, Miyawaki Nobumasa +8 more

Ion implantation is an accelerator-based technology used to create defects and introducing impurities into solid materials. A research and development study is currently underway toward ultrahigh-precision single-ion implantation using laser-cooling techniques at Takasaki Institute, National Institutes for Quantum Science and Technology. To achieve this, we incorporate a linear Paul trap as an ultracold single-ion source, where trapped ions can be made “Coulomb-crystallized” through Doppler laser cooling. In our scheme, nitrogen or silicon ions, useful for ion implantation to create color centers in materials, are sympathetically cooled through Coulomb collisions by co-trapping them with laser-cooled calcium ions to form a two-component crystal. These cold ions are then selectively extracted from the trap to be accelerated and focused through a 50-kV electrostatic bipotential-lens system. Our goal is to achieve beam focusing for ultrahigh-precision implantation on the order of 10 nm. The implanter system has already been assembled, and the commissioning is currently ongoing to enable single-ion extraction using a Coulomb crystal. In these proceedings, we describe the scheme for selective ion extraction and nanobeam focusing based on multiparticle simulations and briefly report recent progress in system implementation.

Ramón Aguado, R. Citro, Maciej Lewenstein +1 more

Yosuke Yuri, Kouichi Hosaka, Nobumasa Miyawaki +9 more

Ion implantation is an accelerator technology essential for creating defects or introducing impurities into materials. A research and development study is currently underway at QST Takasaki Institute toward ultrahigh-precision single-ion implantation based on laser-cooling techniques. To achieve this, we incorporate a linear Paul trap as an ultracold single-ion source, where trapped ions can be cooled to the order of mK or even “Coulomb-crystallized” by Doppler laser cooling. In our scheme, N or Si ions, useful for ion implantation to create color centers, are sympathetically cooled down to the mK range through Coulomb collisions by co-trapping them with laser-cooled Ca ions. Then, the ions are extracted selectively from the trap to be accelerated and focused through a 50-kV electrostatic bipotential lens system. We aim to focus the ions on the order of 10 nm for ultrahigh-precision implantation. The implantation system has already been assembled, and the commissioning is currently underway to enable ion extraction using a Coulomb crystal and focusing extracted cold ions. We present the status of system development and outline the scheme for selective ion extraction and nanobeam focusing based on multiparticle simulations.

Tanmoy Chakraborty, F. Lehmann, J. Zhang +6 more

Applications of nitrogen-vacancy (NV) centers in diamond in quantum technology have attracted considerable attention in recent years. Deterministic generation of ensembles of NV centers can advance the research on quantum sensing, many-body quantum systems, multipartite entanglement, and so on. Here we report the complete process of controlled generation of NV centers in diamond as well as their characterization: growing diamond films through chemical vapor deposition (CVD), ion implantation, and spectroscopic characterization of the defect centers using a confocal microscope. A microwave-assisted CVD setup is presented which we constructed for the preparation of single-crystalline homoepitaxial diamond films. The films were prepared with minimized nitrogen concentration, which is confirmed through photoluminescence measurements. We demonstrate an in situ ultrahigh vacuum (UHV) implantation and heating process for creation of NV centers using a novel experimental setup. For the first time hot implantation has been shown which prevents surface charging effects. We do not observe graphitization due to UHV heating. By optimizing the implantation parameters it has been possible to implant NV centers in a precise way. We present large area mapping of the samples to determine the distribution of the centers and describe the characterization of the centers by spectroscopic techniques. Reducing the decoherence caused by environmental noise is of primary importance for many applications in quantum technology. We demonstrate improvement on coherence time ${T}_{2}$ of the NV spins by suppression of their interaction with the surrounding spin bath using robust dynamical decoupling sequences.

Sophia Chen