Logo Leibniz Universität Hannover
Logo: Institut für Quantenoptik/Leibniz Universität Hannover
Logo Leibniz Universität Hannover
Logo: Institut für Quantenoptik/Leibniz Universität Hannover
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Trapped-Ion Quantum Information and Simulation

Welcome to our group! We use trapped ions for quantum information processing and for precision measurements.

Group picture 2014. 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

News

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 collaborationapproved 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 are developping techniques for quantum logic inspired cooling and detection of single (anti-)protons. These techiques are aimed at a test of CPT invariance based on the (anti-)proton's magnetic moment which is currently under developement with the BASE collaboration (Baryon-Antibaryon Symmetry Experiment). 

This quantum logic inspired 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.

Conceptual picture of QLEDS Penning trap array for quantum logic cooling and readout of single (anti-)protons. Picture credit: M. Niemann.

Quantum logic and simulation

Illustration of optimized near-field conductor structure (M. Carsjens)
Optimized near-field trap structure produced in PTB cleanroom facility.
Fluroescence from 9Be+ ion in surface-electrode trap.

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).

Labs

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.

Funding

We acknowledge funding by ERC (ERC-StG "QLEDS"), NTH, Laserlab Europe, Leibniz Universität Hannover, PTB and the cluster of excellence QUEST.