Fast quantum gates and coherent control with trapped ions
Juan José García‐Ripoll, Peter Zoller, Ignacio Cirac · 2004
Trapped ions are one of the most promising systems to implement quantum computations. In fact, there seems to be no fundamental obstacle to scale-up existing set-ups [1,2]. This is achieved by moving the ions without affecting their internal state, something that has been successfully demonstrated. The current limitations of trapped ions lie in the performance of the two--qubit quantum gates which are required for universal quantum computations. In particular, the time required to perform a gate is limited by the frequency of the trap holding the ions, something which cannot be increased arbitrarily. In this work [3] we show that such a time limitation is by no means fundamental. In fact, we propose a new concept of quantum gate which is not limited by the trap frequency, is completely independent of the temperature (even beyond the Lamb-Dicke limit), and requires no addressability. We also analyze the performance of quantum gates based on this new scheme.