P – 30677

December 14, 2017 8:59 am Published by

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Principal Investigator: Dr. Stephan Sponar

Duration: 01.01.2018 – 31.12.2022

Funding Amount: 339 kEUR

Heisenberg’s uncertainty principle is, without any doubt, one of the most profound statements in modern quantum physics. Its widespread formulation in terms of standard deviations captures the essence of quantum mechanics and is a consequence of a very basic approach of this particular theory, namely to treat massive particles as travelling waves. However, Heisenberg’s original formulation is based on a description of an (underlying) measurement process. The reintroduction of this concept, generally referred to as error-disturbance uncertainty relations, has gained a lot of attention in recent years, both on theoretical and experimental sides. In this project we proceed with experimental studies of weak values, i.e., extended values of an observable depended on both a pre– and a post-selected state vector, as well as generalized error-disturbance uncertainty relations using neutron matter waves.

Scientific Achievements:

  • Experimental test of uncertainty principle in joint unsharp measurements

  • Observation of a strengthened relation for operationally defined error-disturbance uncertainty relations

  • Entropic uncertainty relations for non-orthogonal observables

  • Tight Noise-noise uncertainty relation

 Publications:

H. Lemmel, N. Geerits, A. Danner, H. F. Hofmann, and S. Sponar, Quantifying the presence of a neutron in the paths of an interferometer, Physical Review Research 4, 023075 (2022) or arXiv:2202.00272 [quant-ph].

S. Sponar, A. Danner, M. Ozawa, and Y. Hasegawa, Neutron Optical Test of Completeness of Quantum Root-Mean-Square Errors, npj Quantum Information 7, 106 (2021) or arXiv:2009.06418 [quant-ph].

R. Wagner, W. Kersten, A. Danner, H. Lemmel, A. Kumar Pan, and S. Sponar, Direct experimental test of commutation relation via imaginary weak value, Physical Review Research 3, 023243 (2021) or arXiv:2012.08171 [quant-ph].

S. Sponar, A. Danner, V. Pecile, N. Einsidler, B. Demirel, and Y. Hasegawa, Experimental Test of Entropic Noise-Disturbance Uncertainty Relations for Three-Outcome Qubit Measurements, Physical Review Research 3, 023175 (2021) or arXiv:2005.13410 [quant-ph].

S. Sponar, R. I. P. Sedmik, M. Pitschmann, H. Abele, and Y. Hasegawa, Tests of fundamental quantum mechanics and dark interactions with low-energy neutrons, Nature Reviews Physics 3, 309 – 327 (2021), DIO: 10.1038/s42254-021-00298-2, Extended Vers. [quant-ph/2012.09048].

S. Sponar, A. Danner, K. Obigane, S. Hack, and Y. Hasegawa, Experimental Test of Tight State-Independent Preparation Uncertainty Relations for Qubits, Physical Review A 102, 042204 (2020) or [quant-ph/2002.10725].

A. Danner, B. Demirel, W. Kersten, H. Lemmel, R. Wagner, S. Sponar, and Y. Hasegawa, Spin-rotation coupling observed in neutron interferometry, npj Quantum Information 6, 23 (2020) or [quant-ph/1904.07085].

B. Demirel, S. Sponar, and Y. Hasegawa, Measurements of Entropic Uncertainty Relations in Neutron Optics,
Applied Science 10, 1087 (2020).

S. Sponar, H. Geppert-Kleinrath, T. Denkmayr, H. Lemmel, and Y. Hasegawa, Asking Neutrons where they have been,
J. Phys.: Conf. Ser. 1316, 012002 (2019).

R. Wagner, L. Brandl, W. Kersten, S. Sponar, Y. Hasegawa, C. Huber, F. Bruckner and D. Suess, 3D printed magnets for neutron spin manipulation, EPJ Web Conf. 219, 10008 (2019).

W. Kersten, L. Brandl, R. Wagner, C. Huber, F. Bruckner, A. Hasegawa, D. Suess, and S. Sponar, Additive-Manufactured and Topology-Optimized Permanent-Magnet Spin Rotator for Neutron Interferometry, Physical Review Applied 12, 014023 (2019) or [quant-ph/1810.13225 ].

A. Danner, B. Demirel, S. Sponar and Y. Hasegawa, Development and perfomance of a miniaturised spin rotator suitable for neutron interferometer experiments, Journal of Physics Communications 3, 035001 (2019).

B. Demirel, S. Sponar, A. A. Abbott, C. Branciard, and Y. Hasegawa, Experimental test of an entropic measurement uncertainty relation for arbitrary qubit observables, New Journal of Physics 21, 013038 (2019) or [quant-ph/1711.05023].

H. Geppert-Kleinrath, T. Denkmayr, S. Sponar, H. Lemmel, T. Jenke, and Y. Hasegawa, Multifold paths of neutrons in the three-beam interferometer detected by a tiny energy kick, Physical Review A 97, 052111 (2018) or [quant-ph/1805.05093].

T. Denkmayr, J. Dressel, H. Geppert-Kleinrath, Y. Hasegawa. and S. Sponar, Weak values from strong interactions in neutron interferometry, Physica B, 551, 339-346  (2018).