Measurement of quantum states of neutrons in the Earth’s gravitational field

Nesvizhevsky, V. V.; Börner, Hans G.; Gagarski, A. M.; Petoukhov, A.; Petrov, G. A.; Abele, H.; Baeßler, S.; Divkovic, G.; Rueß, Frank J.; Stöferle, Thilo; Westphal, Alexander; Strelkov, A. V.; Протасов, К. В.; Voronin, A. Yu.

doi:10.1103/physrevd.67.102002

Cited by 242 publications

(307 citation statements)

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“…certain conditions, this problem can be reduced to a quantum particle above a mirror in a linear potential-the so-called quantum bouncer 10 , in analogy to the neutron quantum motion in the Earth's gravitational field above a flat mirror 11,[21][22][23][24][25][26] . Thus, we used similar approaches for the two problems; this analogy motivated the present study to a significant extent, as well as a consideration of a 'neutron centrifuge' in ref.…”

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Neutron whispering gallery

et al. 2009

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The 'whispering gallery' effect has been known since ancient times for sound waves in air 1,2 , later in water and more recently for a broad range of electromagnetic waves: radio, optics, Roentgen and so on 3-6 . It consists of wave localization near a curved reflecting surface and is expected for waves of various natures, for instance, for atoms 7,8 and neutrons 9 . For matter waves, it would include a new feature: a massive particle would be settled in quantum states, with parameters depending on its mass. Here, we present for the first time the quantum whispering-gallery effect for cold neutrons. This phenomenon provides an example of an exactly solvable problem analogous to the 'quantum bouncer' 10 ; it is complementary to the recently discovered gravitationally bound quantum states of neutrons 11 . These two phenomena provide a direct demonstration of the weak equivalence principle for a massive particle in a pure quantum state 12 . Deeply bound whispering-gallery states are long-living and weakly sensitive to surface potential; highly excited states are short-living and very sensitive to the wall potential shape. Therefore, they are a promising tool for studying fundamental neutron-matter interactions 13-15 , quantum neutron optics and surface physics effects [16][17][18] .The classical whispering-gallery phenomenon can be understood in terms of geometrical optics. Thus, neutron Garland trajectories with a high probability of specular reflection have been observed in curved neutron guides 19 and frequently used in neutron experiments. Elliptical focusing neutron guides using a single reflection are available in commerce. Sound can be reflected in an elliptical chamber from one focus to the other one after 'a single bounce'. A more complex phenomenon consists of wave localization in the vicinity of curved surfaces, also called the whispering-gallery effect. Owing to such localization, the sound can reach a person on the opposite side of a building, or even complete a circle, imitating an 'echo'. Lord Rayleigh explained and described quantitatively this phenomenon in his 'Theory of sound' 1,2 . He verified the theory using a whistle as a sound source and burning candles as the sound intensity 'detectors'. Whales are believed to communicate over long distances, profiting from a similar effect in surface layers of sea water. The electromagnetic whispering-gallery waves from radio to light ('glory' or 'heiligenschein') and Roentgen frequencies are of ever-growing interest 3-6 owing to their multiple applications. They are also known as 'Mie scattering' in light scattering from aerosols and in nuclear physics. An optical analogue of a quantum particle bouncing on a hard surface under the influence of gravity or centrifugal potential has been demonstrated recently using a circularly curved optical waveguide 20 . In all of these cases, a curved mirror acts as a waveguide; and interference of the waves falling to the mirror and those reflected causes specific stationary whispering-gallery modes.For a material wave ...

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confidence: 99%

Neutron whispering gallery

et al. 2009

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“…In the experimental method used [16,17,18,19] UCN move above a nearly perfect horizontal mirror in the presence of the Earth's gravitational field. A combination of a mirror and the gravitational potential binds neutrons close to the mirror surface in the so-called gravitational states.…”

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Constraint on the coupling of axionlike particles to matter via an ultracold neutron gravitational experiment

et al. 2007

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We present a new constraint for the axion monopole-dipole coupling in the range of 1 µm -a few mm, previously unavailable for experimental study. The constraint was obtained using our recent results on the observation of neutron quantum states in the Earth's gravitational field. We exploit the ultimate sensitivity of ultra-cold neutrons (UCN) in the lowest gravitational states above a material surface to any additional interaction between the UCN and the matter, if the characteristic interaction range is within the mentioned domain. In particular, we find that the upper limit for the axion monopole-dipole coupling constant is gpgs/( c) < 2 10 −15 for the axion mass in the "promising" axion mass region MA ∼ 1 meV.A vanishing value for the neutron electric dipole moment motivated the introduction of hypothetical light (pseudo) scalar bosons (commonly called axions), as an extension of the Standard Model [1,2,3,4]. According to the suggested theories the axion mass could be in the range of 10 −6 < M A < 10 −1 eV, while its coupling to photons, leptons and nucleons is not fixed by the existing models (though it is extremely weak). Following the theoretical predictions mentioned intensive searches for axions have been performed over recent decades. These studies include testing the astrophysical consequences of the axion theories, QED effects (axion-two photon coupling) and macroscopic forces (spin-matter coupling). They put severe constraints on axion-matter coupling in different axion mass ranges. A detailed review of axion studies can be found in [5,6].The recently reported positive results of the PVLAS experiment on light polarization rotation in a vacuum in the presence of a transverse magnetic field [7] may be seen as evidence of the long sought axion [8]. According to [7], the mass of neutral boson possibly responsible for the observed signal is 1 < M A < 1.5 meV.The value of the axion-photon coupling strength obtained from the PVLAS experiment is in contradiction with recent CAST observations [9]. Several ideas have been discussed recently, in [10,11], capable of explaining this discrepancy.This intriguing result makes it particularly important to carry out independent testing on the axion-matter coupling in the corresponding distance range of 130 < λ < 200 µm.In the present Letter we report on constraints for axion monopole-dipole coupling. Such coupling results in a spin-matter CP violating Yukawa-type interaction potential [12]between spin and matter, where g p g s is the product of couplings at the scalar and polarized vertices and λ is the force range. Here r is the distance between a neutron and a nucleus, n = r/r is a unitary vector, and m is the nucleon mass. Only a few experiments for distances below 100 mm have placed upper limits on the product coupling in a system of magnetized media and test masses [6]. One experiment [13] had peak sensitivity at ∼ 100 mm and two other ones [14,15] had peak sensitivity at ∼ 10 mm.The constraint for the g s g p presented in this article is competitive in the dista...

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“…A ground state filter made from the bottom mirror and a scatterer with a rough bottom surface that leaves an open slit height of about z slit ∼ 25 µm accepts ground state neutrons and rejects neutrons in higher quantum states. Earlier experiments [1][2][3] demonstrate the operation of this filter. The resonance condition in the transition region can only be fulfilled for neutrons with a certain velocity in forward direction.…”

Section: Spectroscopy Of Quantum-mechanical Bound Statesmentioning

confidence: 66%

Frequency shifts in gravitational resonance spectroscopy

et al. 2015

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Quantum states of ultracold neutrons in the gravitational field are to be characterized through gravitational resonance spectroscopy. This paper discusses systematic effects that appear in the spectroscopic measurements. The discussed frequency shifts, which we call Stern-Gerlach shift, interference shift, and spectator state shift, appear in conceivable measurement schemes and have general importance. These shifts have to be taken into account in precision experiments.

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Measurement of quantum states of neutrons in the Earth’s gravitational field

Cited by 242 publications

References 15 publications

Neutron whispering gallery

Neutron whispering gallery

Constraint on the coupling of axionlike particles to matter via an ultracold neutron gravitational experiment

Frequency shifts in gravitational resonance spectroscopy

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