Abstract
Evanescent waves are ubiquitous at interfaces with optical, seismic or acoustic waves, and also with electron, neutron or atom beams. Newton was the first to suspect that both small time delays and spatial shifts exist during total internal reflection. However, these effects are so tiny that the spatial shifts were only observed in 1947 in optics, whereas the time delay values predicted by the Wigner model in the 10−14 s range in optics had to await femtosecond lasers to be detected with difficulty. The spatial shifts have been isolated in many areas but the time delays, though fundamental, generally remain out of reach, particularly with particles. In textbooks usually both quantities are supposed to be simply linked. Here we report, using swivelling detectors, that the spatial and temporal measurements are intimately intermingled, especially in the so-called cyclical regime. Indeed, while the spatial shift does not depend on the type of detection, the measured time delay can be positive, negative or zero, but controllable. We also discuss how such intricate measurements of spatial and temporal effects allow crucial time penalties to be eliminated in guided soliton propagation, and should be used to unambiguously identify the Newton-Wigner time delays for particles.
Highlights
Suggesting a mechanical corpuscular model of light, Newton was the first to observe and use evanescent waves at total reflection[1]
In contrast to the measurement of spatial shifts that remain unchanged in a continuous wave or a pulsed regime, the measurement of time delays requires a pulse regime with short optical pulses and is expected to exhibit experimentally paradoxical dynamics, according to the chosen finish line
On the other hand, combining spatial shifts with time delays could provide us with the possibility to compensate for unwanted penalties occurring in fast phenomena such as soliton propagation
Summary
Suggesting a mechanical corpuscular model of light, Newton was the first to observe and use evanescent waves at total reflection[1]. From the experimental point of view, while the spatial shift requires only a continuous wave (CW) set-up to be observed, measuring the Newton-Wigner time delay (in the range of 10−14 s in optics) necessitates short pulses, a reference clock, and an appropriate finish line for the arrival of two pulses, when two spatially separated trajectories are used. The measurement of such delays requires detecting the difference between the time arrivals of two pulses propagating along parallel pathways. Beyond the difficulties to access the delays, several experiments[22,23,24] have used counterintuitive schemes, where the detection line is oriented parallel to the interface
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
