Trapped-Ion Quantum Engineering
Welcome to our group! We use trapped ions for quantum information processing, in particular quantum simulation, and for precision experiments.
Group picture 2013. From right to left: Henning Hahn, Matthias Kohnen, Christina Vollmer, Mariia Stepanova, Kai Voges, Martina Wahnschaffe, Teresa Feld, Anna-Greta Paschke, Sebastian Grondkowski, Malte Niemann, Timko Dubielzig, Amado Bautista-Salvador, Christian Ospelkaus
March 2015: PhD and postdoc positions available! Please follow this link.
2014: First 9Be+ ions in surface-electrode trap.
December 2013: QLEDS project on proton / antiproton quantum logic manipulation funded by ERC starting grant "QLEDS" with 1.6 million EUR.
November 2013: Paper on surface-electrode trap with optimized near-field microwave control published
June 2013: BASE collaboration approved by CERN Research Board
March 2013: Our group joins the BASE collaboration (Baryon-Antibaryon Symmetry Experiment)
October 2012: Project on microwave near-field surface-electrode trap design funded as NTH bottom-up project
October 2011: We have produced our first surface-electrode traps in the PTB cleanroom facility.
Quantum logic inspired cooling and detection for single (anti-)protons
Within the standard model of particle physics, particles and their antiparticles are predicted to have exactly the same modulus of charge, mass, lifetime and g-factor as a result of CPT invariance (invariance under time reversal, charge conjugation and spatial inversion). In this project, we aim to develop a test of CPT invariance by comparing the proton and antiproton g-factors using quantum logic techniques.
This approach had been proposed by D. Heinzen and D. J. Wineland in 1990 [D. J. Heinzen and D. J. Wineland, Phys. Rev. A, 42 (1990); see also D. J. Wineland et al., J. Res. NIST, 103, 259 (1998)]. The basic idea is to couple the (anti-)proton to an atomic "qubit" ion trapped in its vicinity via the Coulomb interaction and to exploit this coupling both for ground state cooling of single (anti-)protons as well as for state readout.
This project uses some of the same techniques as our project on quantum logic and simulation to achieve the desired coupling between the qubit ion and the (anti-)proton. Compared to our quantum logic surface-electrode traps, this project will employ a miniaturized Penning trap in a 5 Tesla superconducting magnet.
This project is part of the BASE collaboration (Baryon-Antibaryon Symmetry Experiment). Within BASE, we collaborate with researchers from RIKEN, Japan, Max-Planck-Institut für Kernphysik, Heidelberg, Universität Mainz, GSI Darmstadt, and the University of Tokyo, Komaba, Japan. We plan to demonstrate quantum logic manipulation of single protons in Hannover and Braunschweig. If successful, the trap and laser systems could be installed at CERN at the BASE beamline for experiments with antiprotons.
Quantum logic and simulation
We investigate laser-less schemes for quantum state manipulation of trapped ions with respect to quantum simulation. Quantum simulation is a field that was started by Richard Feynman in 1982 and is rapidly expanding both theoretically and experimentally.
With trapped ions in regular surface-electrode trap arrays, one hopes to create artificial interacting spin systems which can shed light on the behavior of quantum many-body systems [Schmied et al., PRL 102, 233002 (2009)]. Those can be exponentially hard to simulate even on today's supercomputers. One of our aims is to apply integrated microwave techniques [C. Ospelkaus et al., PRL 101, 090502 (2008); C. Ospelkaus et al., Nature 476, 181 (2011)] to quantum simulation [see also Chiaverini and Lybarger, PRA 77, 022324 (2008)]. This could provide a highly integrated and scalable approach to quantum simulation.
We have recently developed a surface-electrode trap with optimized, integrated near-field microwave control [M. Carsjens et al., Applied Physics B, November 2013] based on powerful finite-element simulations of microwave near-fields as a first step towards that goal. The trap has been fabricated and has recently trapped ions for the first time (see right-hand side image).
Our group has labs both at Leibniz Universität Hannover and at PTB in Braunschweig. We have experimental setups in both locations. Our trap production and characterization effort is concentrated at PTB in Braunschweig.
We acknowledge funding by ERC (ERC-StG "QLEDS"), NTH, Laserlab Europe, Leibniz Universität Hannover, PTB and the cluster of excellence QUEST.