Quantum imaging with undetected photons

A system, comprising:

• a coherent light source adapted to emit a coherent photon beam with a wavelength λ0;
• a first non-linear medium adapted to generate one or more first correlated photon pairs responsive to the coherent photon beam incident upon the first non-linear medium, each pair comprising two photons with a wavelength λ1 and a wavelength λ2, respectively, thereby generating a first and a second photon beam with the wavelengths λ1 and λ2, respectively, wherein the wavelength λ1 does not equal the wavelength λ2 and the first photon beam is adapted to illuminate an object;
• a second non-linear medium adapted to generate one or more second correlated photon pairs responsive to the coherent photon beam and the first photon beam incident upon the second non-linear medium, each pair comprising two photons with the wavelength λ1 and the wavelength λ2, respectively, thereby generating a third and a fourth photon beam with the wavelengths λ1 and λ2, respectively;
• a dichroic mirror adapted to overlap the photons of wavelength λ2 of the first correlated photon pairs with the photons of wavelength λ2 of the second correlated photon pairs, such that the overlapped photons of wavelength λ2 are indistinguishable;
• and
• an imaging device adapted to detect the overlapped photons of wavelength λ2 for imaging the object, such that the photons of wavelength λ1 that illuminate the object are not detected.