We propose a fully optical method to perform any quantum computation by supplying the prescriptions for a universal set of quantum gates. We also give the methods for the generation of input states and the realization of final measurements. The apparatus is scalable, and relies on high Kerr non-linearities.
Fortschr. Phys. 48 (2000) 5Β± Β±7, 573 Β± Β± 577 3.
Conclusions
We have presented a method to perform any quantum computation in a fully optical way, by encoding each qubit in a single photon polarization state. A universal set of gates has been proposed, along with the prescriptions for the generation of the input states and for the retrieval of the final results at the end of the quantum computation. A study of the practical feasibility of the Hamiltonian of the device needed to implement the Controlled-NOT gate was given. The proposed universal set of gates is fully scalable, since it is possible to increase the network size, without having an exponential increase in its physical resources. The decoherence in this setup is very low, and it is mostly due to losses in the Kerr medium. The major limitation in the practical realization of the present proposal is the very high Kerr nonlinearities that are needed. However, since methods for achieving Giant Kerr shifts by using electromagnetically induced transparency have been recently proposed we think that the present scheme may open new perspectives for experimental quantum computation.