Authors: Hussain, M., I; Heinrich, D.; Guevara-Bertsch, M.; Torrontegui, E.; Garcia-Ripoll, J. J.; Roos, C. F.; Blatt, R.


Publication date: 2021/02/23

DOI: 10.1103/PhysRevApplied.15.024054

Abstract: The conventional approach to perform two-qubit gate operations in trapped ions relies on exciting the ions on motional sidebands with laser light, which is an inherently slow process. One way to implement a fast entangling-gate protocol requires a suitable pulsed laser to increase the gate speed by orders of magnitude. However, the realization of such a fast entangling-gate operation presents a big technical challenge, as such the required laser source is not available off the shelf. For this, we engineer an ultrafast entangling-gate source based on a frequency comb. The source generates bursts of several hundred mode-locked pulses with pulse energy approximately 800 pJ at 5-GHz repetition rate at 393.3 nm and complies with all requirements for implementing a fast two-qubit gate operation. Using a single, chirped ultraviolet pulse, we demonstrate a rapid adiabatic passage in a Ca+ ion. To verify the applicability and projected performance of the laser system for inducing entangling gates we run simulations based on our source parameters. The gate time can be faster than a trap period with an error approaching 10(-4).