Daniele Parodi | Searcharxiv

arXiv2007

Environmental noise reduction for holonomic quantum gates

We study the performance of holonomic quantum gates, driven by lasers, under the effect of a dissipative environment modeled as a thermal bath of oscillators. We show how to enhance the performance of the gates by suitable choice of the loop in the manifold of the controllable parameters of the laser. For a simplified, albeit realistic model, we find the surprising result that for a long time evolution the performance of the gate (properly estimated in terms of average fidelity) increases. On the basis of this result, we compare holonomic gates with the so-called stimulated Raman adiabatic passage (STIRAP) gates.

quant-ph↗

arXiv2006

Fidelity optimization for holonomic quantum gates in dissipative environments

We analyze the performance of holonomic quantum gates in semi-conductor quantum dots, driven by ultrafast lasers, under the effect of a dissipative environment. In agreement with the standard practice, the environment is modeled as a thermal bath of oscillators linearly coupled with the excitonic states of the quantum dot. Standard techniques of quantum dissipation make the problem amenable to a numerical treatment and allow to determine the fidelity (the common gate-performance estimator), as a function of all the relevant physical parameters. As a consequence of our analysis, we show that, by varying in a suitable way the controllable parameters, the disturbance of the environment can be (approximately) suppressed, and the performance of the gate optimized--provided that the thermal bath is purely superhomic. We conclude by showing that such an optimization it is impossible for ohmic environments.

quant-ph↗