Title: High-precision sensing based on thermal light interference beyond coherence
Abstract: In the mid fifties Hanbury-Brown and Twiss (HBT) proposed to measure the angular dimension of stars by retrieving second-order interference in the absence of first-order interference. Remarkably, the HBT effect was at the heart of the development of the field of quantum optics. We describe here a novel interference scheme where two classically correlated beams of light produced by beam-splitting of a thermal light beam as in an HBT scheme are sent to two unbalanced Mach-Zehnder interferometers before a second order correlation measurement is performed.
The unbalancing between the long and the short arm of the interferometers is such that no first-order interference exists at each detector, separately. Nonetheless, second-order interference was theoretically predicted [1] and recently experimentally verified [2] to occur between the long-long and short-short pairs of path. This effect seems to contradict our common understanding of optical coherence. Furthermore, differently from an HBT scheme, sinusoidal fringes can be observed as a function of the difference between the relative phases in the two Mach-Zehnder interferometers, independently of how far the two interferometers are placed with respect to each other. Therefore, this phenomenon has the potential for the development of novel remote sensing and imaging applications. Indeed, we showed how, when employed in the spatial domain, enables to monitor the transverse position and the spatial structure of two distant double-slit masks [3], as verified experimentally in Ref. [4]. Finally, the correlations associated with the two pairs of interfering paths can be employed to simulate a controlled-NOT gate [1,3], as experimentally verified in Ref. [5].
[1] V. Tamma, & J. Seiler, Multipath correlation interference and controlled-not gate simulation with a thermal source, New J. of Physics 18 032002 (2016)
[2] Y. S. Ihn, Y. Kim, V. Tamma, & Y.H. Kim, Second-order temporal interference with thermal light: Interference beyond the coherence time, , Phys. Rev. Lett. 119, 263603 (2017)
[3] M. Cassano, M. D’Angelo, A. Garuccio, T. Peng, Y. Shih, & V. Tamma, Spatial interference between pairs of disjoint optical paths with a chaotic source, Opt. Express 25, 6589 (2017)
[4] M. D’Angelo, A. Mazzilli, F. V.Pepe, A. Garuccio, & V. Tamma, Characterization of two distant double-slit by chaotic light second-order interference, Sci. Rep. 7, 2247 (2017)
[5] T. Peng, V. Tamma, & Y Shih, Experimental controlled-not gate simulation with thermal light, Sci. Rep. 6, 30152 (2016)
