Longitudinal Coherence in Neutron Interferometry

Abstract

of the oscillations in real space is somewhat longer on the trailing edge than on the leading edge. Therefore, interference effects are only observable when the two wave packets are nearly coincident as discussed by Klein, Opat, and Hamilton. 10 To our knowledge, this is the first experiment in which the detailed longitudinal shape of a neutron wave packet has been observed, and the uncertainty relation for neutrons in the longitudinal direction explicitly verified.

Coherence and spectral filtering in neutron interferometry

“…From Eq. (10), we see that this affects the behavior of the contrast curves. However, if the incident spectrum go(A, ) is measured, Eq.…”

“…However, if the incident spectrum go(A, ) is measured, Eq. (10) can be used to predict the shape of the contrast curve Cz;, (D). & is given by C. Phase difFerence between the C2 and analyzed C3 beams It is a well-known fact that the interferogram patterns in the C2 and C3 exit beams differ in phase by 180', that 1s,…”

“…In principle, the maximum contrast Cc3(0) in the C3 beam may vary from 0% to 100%, depending on how well the interferometer performs; experi-Or, if the displacement b l is in the longitudinal direction (parallel to k), we can replace~a(k)~by the wavelength spectrum g(A, ) to calculate I (D, a), namely r(D ) -1 f + (g) (40+4P( )+rS (D))dg &2m. (10) For this experiment ys &&Pp, so that the phase rotator has a negligible effect on the contrast. Thus, for a Gaussian distribution~a(k)~, the relative contrast falls off as a function of the sample thickness D according to the formula -(XbDa) ) /2 Such relative contrast curves were first measured for neutron interferometry by Kaiser, Werner, and George [7].…”

“…(6) for the intensity I(D,a) depends only on the magnitude~o(k)~of the spectrum a(k) [8]. There are therefore two interpretations as to why the relative contrast decreases with increasing sample thickness; both are equally valid and experimentally indistinguishable [9,10]. First, we know that a wave packet spreads as it propagates, with the faster wavelength components tending toward the leading end of the packet, and the slower components toward the trailing end.…”

The photo-neutronrefractive effect

“…Some very recent and amazing results on quantum states of the neutron in the gravitational field demonstrate the demand of further research on those topics [84]. Coherence and de-coherence effects, which are important in any experiment, were investigated [52,85,86]. Based on the knowledge about the neutron and being interested in fundamental questions of physics, several groups started to elaborate interferometry with more complex quantum objects like atoms [87,88,89,90] and molecules [91].…”