Through the Eye of the Needle

Klaus Mølmer

Jacob Dunningham

Akira Imada

If we want to break someone else's PIN (personal identification number) of, say, an ATM (automated teller machine), how many trials would be necessary when we want to be efficient? This is a sort of what we calla-needle-in-a-hay-stackproblem. In 1987, in their wonderful paper, Hinton & Nowlan proposed a genetic algorithm with a needle being a unique configuration of 20-bit binary string while all other configurations being a haystack. What they proposed was to exploit alifetimelearningof individuals in their genetic algorithm, calling it the Baldwin effectinacomputer. Since then there has been a fair amount of exploration of this effect, claiming, "this is a-needle-in-a-hay-stack problem, and we've found a more efficient algorithm than a random search." Some of them, however, were found to be the results of an effect oflike-to-hear-what-we-would-like-to-hear. In this talk, we will try a bird's eye view on a few examples we have had so far, and how they were explored, including the approach by means of quantum computation which claims, "The steps to find a needle areO(radicN) while those of exhaustive search by a traditional computer are O(N) whereNis the number of search points."

Nikhil Kotibhaskar, Noah Greenberg, Sainath Motlakunta +2 more

Despite the progress in building sophisticated microfabricated ion traps, Paul traps employing needle electrodes retain their significance due to the simplicity of fabrication while producing high-quality systems suitable for quantum information processing, atomic clocks, etc. For low noise operations such as minimizing "excess micromotion," needles should be geometrically straight and aligned precisely with respect to each other. Self-terminated electrochemical etching, previously employed for fabricating ion-trap needle electrodes, employs a sensitive and time-consuming technique, resulting in a low success rate of usable electrodes. Here, we demonstrate an etching technique for the quick fabrication of straight and symmetric needles with a high success rate and a simple apparatus with reduced sensitivity to alignment imperfections. The novelty of our technique comes from using a two-step approach employing turbulent etching for fast shaping and slow etching/polishing for subsequent surface finish and tip cleaning. Using this technique, needle electrodes for an ion trap can be fabricated within a day, significantly reducing the setup time for a new apparatus. The needles fabricated via this technique have been used in our ion trap to achieve trapping lifetimes of several months.

Olimpiu G. Urcan