CMT Seminar: Ultrafast control of trapped atomic ions

Thursday, October 24, 2013 – 1:30pm – 3:00pm
Regents 351
Brian Neyenhuis
Joint Quantum Institute of UMD and NIST

Trapped atomic ions allow us to build up strongly interacting quantum systems one atom at a time. The internal energy levels of the ion are used to represent a spin 1/2 system and contain a quantum bit (qubit) of information. By applying state-dependent optical dipole forces to the chain of ions we control spin-spin couplings and can engineer interesting Hamiltonians. I will present a new method using ultrafast laser pulses to entangle pairs of ions. We engineer a short train of intense laser pulses to impart a spin-dependent kick, where each spin state receives a discrete momentum kick in opposite directions. Using a series of these spin-dependent kicks we can realize a two qubit gate. In contrast to gates using spectroscopically resolved motional sidebands, these gates may be performed faster than the trap oscillation period, making them potentially less sensitive to noise, independent of temperature, and more easily scalable to large crystals of ions. Multiple kicks can be strung together to create a “Schrodinger cat” like state, where the large separation between the two parts of the wavepacket allow us to accumulate the phase shift necessary for a gate in a shorter amount of time. I will present a realistic pulse scheme for a two ion gate, and our progress towards its realization.

Host: Jim Freericks