Is a single photon's wave front observable?
ZagoskinAlexandre
WilsonRichard D.
EverittMark
Savel'evSergey
GulevichDmitry R.
AllenJ.
DubrovichV.K.
Il'ichevE.
2015
We propose a method of resolving a spatially coherent signal, which contains on average just a single photon,
against the background of local noise at the same frequency. The method is based on detecting the signal
simultaneously in several points more than a wavelength apart through the entangling interaction of the
incoming photon with the quantum metamaterial sensor array. The interaction produces the spatially
correlated quantum state of the sensor array, characterised by a collective observable (e.g., total magnetic
moment), which is read out using a quantum nondemolition measurement. We show that the effects of local
noise (e.g., fluctuations affecting the elements of the array) are suppressed relative to the signal from the
spatially coherent field of the incoming photon as ~1√N, where N
is the number of array elements. The
realisation of this approach in the microwave range would be especially useful and is within the reach of
current experimental techniques.