# Passive CPHASE Gate via Cross-Kerr Nonlinearities.

@article{Brod2016PassiveCG, title={Passive CPHASE Gate via Cross-Kerr Nonlinearities.}, author={Daniel Jost Brod and Joshua Combes}, journal={Physical review letters}, year={2016}, volume={117 8}, pages={ 080502 } }

A fundamental and open question is whether cross-Kerr nonlinearities can be used to construct a controlled-phase (cphase) gate. Here we propose a gate constructed from a discrete set of atom-mediated cross-Kerr interaction sites with counterpropagating photons. We show that the average gate fidelity F between a cphase and our proposed gate increases as the number of interaction sites increases and the spectral width of the photon decreases; e.g., with 12 sites we find F>99%.

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