1. A method for range finding of a target comprising: a) generating a first single photon; b) transmitting the first single photon towards the target; c) generating a second single photon identical to the first single photon; d) delaying the second single photon by a time delay; e) receiving the transmitted first single photon reflected from the target; f) receiving the delayed second single photon; g) interacting the received reflected first single photon and the delayed second single photon to produce Hong-Ou-Mandel (HOM) interference; h) detecting photo-statistics at an output of the HOM interference; i) when the reflected first single photon and the delayed second single photon are output at the same output port, repeating a) to h); j) when the reflected first single photon and the delayed second single photon are output at different output ports, changing the time delay and repeating a) to h); k) repeating a) to j) for a pre-determined number of times to arrive at a final estimate for a value of the time delay; and l) determining the target range corresponding to the final estimate for the value of the time delay after said predetermined number of times.