Simulations and optimisations of long distance ion transport



Scalability of ion trap-based quantum information processing can be achieved by qubit shuttling in multiplexed traps. The shuttling operation time should be faster than the decoherence time of the ions' internal state, while at the same time the ions' external (motional) state have to be maintained as low as possible.  Very recent experiments by groups of Prof. Schmidt-Kaler (Mainz) and Prof. Wineland (NIST) demonstrate such fast transport through a moving trapping potential controlled by varying electrode voltages. In just few microseconds the ions were transported over a distance of more than 104 times the width of the ions' wave function with the motional energy increase of ~ 0.1 quanta.

Our group is interested in numerical simulations of the long
distance  ion  transport  and  optimisation  of  the  required
time-varying control voltages. As the transport distance (d)
is  about  four  orders of magnitude  larger  than  the  wave
packet spatial width (x0), an efficient numerical techniques
having small moveable coordinate (x)  and momentum grid
is required. This is provided by a library of codes designed
by Prof. Koch's group in Kassel.

To perform realistic simulations and open-loop optimisations, realisable electrostatic trapping potentials have  been provided by Prof. Schmidt-Kaler's group.  Our realistic simulations and optimisations pave the way for a wider range of high fidelity and fast ion operations e.g.  deterministic single ion implantation in diamond where rapid switching of trapping potentials is optimised to accelerate the nitrogen ion out of the trap and shoot it into a diamond target with high spatial resolution.



C. Roos, Moving traps offer fast delivery of cold ions, Physics, 5, 94 (2012).

M. Murphy, et. al., High-fidelity fast quantum transport with imperfect controls, Phy. Rev. A 79, 020301(R) (2009).