Limits...
Improvement of the polarized neutron interferometer setup demonstrating violation of a Bell-like inequality.

Geppert H, Denkmayr T, Sponar S, Lemmel H, Hasegawa Y - Nucl Instrum Methods Phys Res A (2014)

Bottom Line: For precise measurements with polarised neutrons high efficient spin-manipulation is required.The gain in performance is exploited demonstrating violation of a Bell-like inequality for a spin-path entangled single-neutron state.The new setup is more flexible referring to state preparation and analysis, therefore new, more precise measurements can be carried out.

View Article: PubMed Central - PubMed

Affiliation: Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Vienna, Austria.

ABSTRACT

For precise measurements with polarised neutrons high efficient spin-manipulation is required. We developed several neutron optical elements suitable for a new sophisticated setup, i.e., DC spin-turners and Larmor-accelerators which diminish thermal disturbances and depolarisation considerably. The gain in performance is exploited demonstrating violation of a Bell-like inequality for a spin-path entangled single-neutron state. The obtained value of [Formula: see text], which is much higher than previous measurements by neutron interferometry, is [Formula: see text] above the limit of S=2 predicted by contextual hidden variable theories. The new setup is more flexible referring to state preparation and analysis, therefore new, more precise measurements can be carried out.

No MeSH data available.


Related in: MedlinePlus

(a) Schematic view of the Larmor accelerator boxes with coils in Helmholtz geometry (yellow), magnetic field (red), neutron beam (green) and water flux (blue), (b) Larmor acceleration coil with Helmholtz geometry in box, (c) closed box with connectors for water cooling, and (d) boxes in the interferometer with connected cooling system and absorber holder for adjustment of the Larmor accelerators. (For interpretation of the references to colour in this figure caption, the reader is referred to the web version of this paper.)
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4375610&req=5

f0035: (a) Schematic view of the Larmor accelerator boxes with coils in Helmholtz geometry (yellow), magnetic field (red), neutron beam (green) and water flux (blue), (b) Larmor acceleration coil with Helmholtz geometry in box, (c) closed box with connectors for water cooling, and (d) boxes in the interferometer with connected cooling system and absorber holder for adjustment of the Larmor accelerators. (For interpretation of the references to colour in this figure caption, the reader is referred to the web version of this paper.)

Mentions: The state preparation requires two Larmor accelerator coils placed in the IFM as shown in Fig. 2. These coils in Helmholtz geometry apply an additional parallel or an anti-parallel field to the guide field in z-direction locally and thereby changing the spin precession in the xy-plane. Since the rotation angle is given by , where μ is the magnetic moment of the neutron, l is the length of the coils and v is the velocity of the neutrons, a magnetic field of about 0.33 mT is required for a spin rotation of π/2. For the fabricated coil a current of about 0.7 A is required for a spin rotation of π/2. Since the coils produce heat and due to the high sensitivity of the IFM to thermal influences, the coils need to be cooled down. The coils are placed in small boxes which are completely flooded with temperature controlled water. The coil wire is in direct contact with the water, insulated only by lacquer. The boxes are made of acrylic glass, which is a thermal and electrical insulator. Length, width and height of the boxes amount to 22, 26 and 26 mm respectively. Fig. 7(a) shows a schematic view of a box. The boxes have a straight passage for the neutron beam (green arrows), so that the beam does not pass any material and therefore no dephasing occurs. The figure also shows the magnetic field in z-direction (red arrow) applied by the coils in Helmholtz configuration (yellow). The flux of the cooling water is depicted by blue arrows. Fig. 7(b) and (c) shows the box without top and finished with the connectors for the water cooling respectively. In Fig. 7(d) one can see the boxes placed in the IFM. In this picture the mountings for beam stoppers between second and third plates of the IFM are depicted. The beam stoppers are used to calibrate the Larmor accelerators one at a time by blocking the other path. The beam stoppers used here are 1 mm thick cadmium plates.


Improvement of the polarized neutron interferometer setup demonstrating violation of a Bell-like inequality.

Geppert H, Denkmayr T, Sponar S, Lemmel H, Hasegawa Y - Nucl Instrum Methods Phys Res A (2014)

(a) Schematic view of the Larmor accelerator boxes with coils in Helmholtz geometry (yellow), magnetic field (red), neutron beam (green) and water flux (blue), (b) Larmor acceleration coil with Helmholtz geometry in box, (c) closed box with connectors for water cooling, and (d) boxes in the interferometer with connected cooling system and absorber holder for adjustment of the Larmor accelerators. (For interpretation of the references to colour in this figure caption, the reader is referred to the web version of this paper.)
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4375610&req=5

f0035: (a) Schematic view of the Larmor accelerator boxes with coils in Helmholtz geometry (yellow), magnetic field (red), neutron beam (green) and water flux (blue), (b) Larmor acceleration coil with Helmholtz geometry in box, (c) closed box with connectors for water cooling, and (d) boxes in the interferometer with connected cooling system and absorber holder for adjustment of the Larmor accelerators. (For interpretation of the references to colour in this figure caption, the reader is referred to the web version of this paper.)
Mentions: The state preparation requires two Larmor accelerator coils placed in the IFM as shown in Fig. 2. These coils in Helmholtz geometry apply an additional parallel or an anti-parallel field to the guide field in z-direction locally and thereby changing the spin precession in the xy-plane. Since the rotation angle is given by , where μ is the magnetic moment of the neutron, l is the length of the coils and v is the velocity of the neutrons, a magnetic field of about 0.33 mT is required for a spin rotation of π/2. For the fabricated coil a current of about 0.7 A is required for a spin rotation of π/2. Since the coils produce heat and due to the high sensitivity of the IFM to thermal influences, the coils need to be cooled down. The coils are placed in small boxes which are completely flooded with temperature controlled water. The coil wire is in direct contact with the water, insulated only by lacquer. The boxes are made of acrylic glass, which is a thermal and electrical insulator. Length, width and height of the boxes amount to 22, 26 and 26 mm respectively. Fig. 7(a) shows a schematic view of a box. The boxes have a straight passage for the neutron beam (green arrows), so that the beam does not pass any material and therefore no dephasing occurs. The figure also shows the magnetic field in z-direction (red arrow) applied by the coils in Helmholtz configuration (yellow). The flux of the cooling water is depicted by blue arrows. Fig. 7(b) and (c) shows the box without top and finished with the connectors for the water cooling respectively. In Fig. 7(d) one can see the boxes placed in the IFM. In this picture the mountings for beam stoppers between second and third plates of the IFM are depicted. The beam stoppers are used to calibrate the Larmor accelerators one at a time by blocking the other path. The beam stoppers used here are 1 mm thick cadmium plates.

Bottom Line: For precise measurements with polarised neutrons high efficient spin-manipulation is required.The gain in performance is exploited demonstrating violation of a Bell-like inequality for a spin-path entangled single-neutron state.The new setup is more flexible referring to state preparation and analysis, therefore new, more precise measurements can be carried out.

View Article: PubMed Central - PubMed

Affiliation: Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Vienna, Austria.

ABSTRACT

For precise measurements with polarised neutrons high efficient spin-manipulation is required. We developed several neutron optical elements suitable for a new sophisticated setup, i.e., DC spin-turners and Larmor-accelerators which diminish thermal disturbances and depolarisation considerably. The gain in performance is exploited demonstrating violation of a Bell-like inequality for a spin-path entangled single-neutron state. The obtained value of [Formula: see text], which is much higher than previous measurements by neutron interferometry, is [Formula: see text] above the limit of S=2 predicted by contextual hidden variable theories. The new setup is more flexible referring to state preparation and analysis, therefore new, more precise measurements can be carried out.

No MeSH data available.


Related in: MedlinePlus