Pinhole quantum ghost imaging

We propose a quantum ghost imaging scheme based on biphotons, which, by using a collimated pump beam of the right size for biphoton generation, obviates the need for lenses to achieve imaging. The scheme is found to be analogous to the classical pinhole camera, where we show that the equivalent to the classical pinhole size depends not only mainly on the width of the pump beam but also on the thickness of the nonlinear crystal and the wavelengths of the biphoton.