Amplitude Interferometry

Lawrence N. Mertz

Chenyu W Hu, Ben Wang, Jiandong Zhang +4 more

Resolving high-contrast targets is a fundamental, yet highly challenging, task in astronomy. Using quantum estimation theory, we demonstrate that the ultimate limit for estimating the separation between two unequal-brightness thermal sources via interferometry remains constant, enabling the potential for superresolution. We give a comparative analysis of two primary stellar interferometric schemes: amplitude interferometry and intensity interferometry. Notably, the nulling strategy employed in amplitude interferometry, a configuration specifically proposed for exoplanet detection by leveraging destructive interference to suppress the brighter source, is quantum optimal for separation estimation. While intensity interferometry is less effective than amplitude interferometry in lossless scenarios and fails to achieve superresolution, it becomes competitive when optical loss in large-scale interferometry is considered. By applying these methodologies to modern stellar interferometry, we highlight the promise of large-scale interferometry for advancing high-resolution astronomical observation.

Timothy J. Schulz, Neeraj K. Gupta

Amplitude interferometry and intensity interferometry are methods for processing the complex amplitude and the intensity, respectively, of an electromagnetic field to estimate the mutual intensity of the field at two spatial locations. Whereas complex amplitude measurements allow for the direct estimation of the mutual-intensity phase, intensity measurements do not. We consider applications for which the estimation of the magnitude or the squared magnitude of the mutual intensity is adequate, and we provide fundamental limits on the estimation accuracy of any unbiased estimator of the squared magnitude of the mutual intensity from coherent (complex amplitude) or incoherent (intensity) measurements. Our analysis is performed for the high-light-level (classical-noise-limit) case and quantifies the advantages of making the more difficult coherent measurements.

Peter Hawkes, Erwin K. Kasper

Johann Summhammer, Klaus A. Hamacher, Helmut Kaiser +3 more

Polarized neutron interferometry has been used to measure the amplitudes for the exchange of up to five photons between the neutron and an oscillating magnetic field. The Rabi spin flip configuration and a configuration in which spin flip is suppressed were investigated, because they raise different questions on the conservation of angular momentum. Because of the linearity of the time-dependent interference signal in the exchange amplitudes, photon exchange probabilities below 1% could be resolved.