A comparative study of an analogue optical Fourier transform quantum computer working in entanglement and non-entanglement mode

摘要

A gedanken model of an analog optical computer for general purpose Fourier transform tasks is built and studied assuming entangled or non-entangled photons appearing at the input. The performance of the entangled and non-entangled operation modes, regarding information content, power consumption, acquisition time, wavelength and bandwidth limitations are analyzed as function of qubit repetition rate and number of qubits in the entangled state, respectively, based on fundamental physical laws. The total number of input photons is assumed the same for the two operation modes. It is sown that the entangled mode outperforms the non-entangled one, but only above a certain number of qubits in the entangled state. It is argued that, for practical applications to general purpose computing, several limitations should be imposed regarding qubit repetition rate and number of qubits in the entangled state. In addition, it is pointed out that the conclusions that we present are equally valid for general purpose optical quantum computing and for quantum information processing, too.