Integrated Quantum Rangefinding


Quantum Rangefinding is a quantum protocol for remote sensing. Inspired by quantum illumination it hinges on the thermal photon-pair probability distribution generated by spontaneous parametric down-conversion. Different from quantum illumination, however, the protocol does not offer an improved signal-to-noise ratio, but perfect covertness guaranteed by the laws of quantum mechanics.

The two-mode squeezed state produced by any spontaneous parametric down-conversion source has the astonishing property that each mode viewed on its own exhibits thermal photon statistics while both modes together are still perfectly correlated. 

This enables perfectly covert rangefinding when a single mode of surrounding background is replaced
with a single mode from a two-mode squeezed state. If the spectral properties of the mode and its brightness can be matched to that of the surrounding background modes, the resulting down-conversion mode becomes undetectable. This means the
Chernoff-bound between the presence and absence of a rangefinder becomes one half and a possible adversary can consequently only guess at best.

BRW cent

The quantum light sources used in quantum rangefinding must be of thermal nature but other properties are less critical. For example high heralding ratios are not necessary. Therefore quantum rangefinding is a well suited first technology demonstration for our Bragg-reflection waveguides. We are working on integrated implementations of quantum rangefinding using Bragg-reflection waveguides in aluminium gallium arsenide as spontaneous-parametric down-conversion sources in the telecom wavelength range.



The Austrian Science Fund funds our IGUANA project "Integrated Quantum Rangefinding" (Q 3)

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