Solid state quantum computer

The control of single atoms and its interactions in solid matter offers a variety of applications in quantum information processing.

Possible realization of a scalable quantum computer based on P donated Si. The donor nuclei spins are used as qubits. Their hyperfine interaction with electron spins alters the charge distribution on the electrodes and achieves the interaction needed for computing and read-out. (B. E. Kane, „A silicon-based nuclear spin quantum computer“, Nature, 393, 133 (1998))

Numerous approaches for the realization of solid state quantum systems exist. Promising candidates are the manipulation of nuclei spins of P doped Si according to B. E. Kane for instance or addressing the ground levels of Nitrogen-Vacancy (NV) centers in diamond, which are split through the Zeeman effect. The last-mentioned approach is particularly interesting as NV centers are noun for their high photo- and temperature resistance, the longevity of their qubits as well as for the possibility of an optical read-out.

Left: Array consisting of NV centers in diamond with a point-to-point distance of 10 µm. Center: Structur of NV in the lattice of diamond. An N-atom substitutes a C, being surrounded by a vacancy. Right: Energy diagram of NV. The groundlevels which are split through Zeeman effect may be used as qubits.

However, contemporary manufacturing processes do not suffice the high requirements concerning doping as they are neither deterministic nor do they reach necessary resolution. Therefore we have developed an atomic nano assembler: A novel device that is capable of implanting an exact number of atoms or molecules in a solid state substrate with high precision regarding both penetration depth and lateral position. This device consists of a linear segmented Paul Trap where ions are trapped and cooled by several cooling processes. The ions, which by now have been formed to a linear crystal, are accelerated out of the trap and implanted in the substrate.

Left: Ion trap optimized for ion implantation. Ion s that shall be extracted are sympathetically cooled through Coulomb-interaction with surrounding laser-cooled Ca ions. This makes the trap universally useable for all types of different ions. Right: Extraction of an ion during implantation into a solid.

The focus of our research is to discover and produce novel customized quantum materials for various applications: Quantum repeaters, triggered multi photon sources, calibrated single photon sources, quantum information circuits as well as sensors with unprecedented accuracy. Since we are especially interested in generating NV centers in diamond, we integrated a confocal microscope into our implantation chamber. This allows to follow the formation of NV centers in-situ.

Left: In-situ microscope image of a pattern consisting of NV centers. Right: The low countrate at small times of the g2-correlation function proves that only a single optically active NV center is in the focus.

Involved Groupmembers

Picture of Prof. Dr. Kilian Talo Theodor  Singer
Prof. Dr. Kilian Talo Theodor Singer
Experimentalphysik I - Licht-Materie-Wechselwirkung
Telephone +49 561 804-4235
E-mail address write an e-mail
Picture of  Karin  Groot-Berning
Karin Groot-Berning
Doktorandin - Experimentalphysik I

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