Publications (34)
Confined Contextuality in Neutron Interferometry: Observing the Quantum Pigeonhole Effect
Mordecai Waegell, Tobias Denkmayr, Hermann Geppert +6
Previous experimental tests of quantum contextuality based on the Bell-Kochen-Specker (BKS) theorem have demonstrated that not all observables among a given set can be assigned non…
Observation of a quantum Cheshire Cat in a matter wave interferometer experiment
Tobias Denkmayr, Hermann Geppert, Stephan Sponar +4
From its very beginning quantum theory has been revealing extraordinary and counter-intuitive phenomena, such as wave-particle duality, Schrödinger cats and quantum non-locality.…
Experimental test of an entropic measurement uncertainty relation for arbitrary qubit observables
Bülent Demirel, Stephan Sponar, Alastair A. Abbott +2
A tight information-theoretic measurement uncertainty relation is experimentally tested with neutron spin-1/2 qubits. The noise associated to the measurement of an observable is de…
Experimental Test of Entropic Noise-Disturbance Uncertainty Relations for Three-Outcome Qubit Measurements
Stephan Sponar, Armin Danner, Vito Pecile +3
Information-theoretic uncertainty relations formulate the joint immeasurability of two non-commuting observables in terms of information entropies. The trade-off of the accuracy in…
Experimental test of symmetron-field based dark energy model using neutron interferometry
Andreas Dvorak, Kazuma Obigane, Hartmut Lemmel +2
We report phase shift measurements of neutron matter waves propagating in vacuum and low-pressure Argon gas, using a technique developed for neutron interferometric scattering leng…
Quantifying the presence of a neutron in the paths of an interferometer
Hartmut Lemmel, Niels Geerits, Armin Danner +3
It is commonly assumed that no accurate experimental information can be obtained on the path taken by a particle when quantum interference between the paths is observed. However, r…
Measuring the Angular Momentum of a Neutron Using Earth's Rotation
Niels Geerits, Stephan Sponar, Kyle E. Steffen +6
A coupling between Earths rotation and orbital angular momentum (OAM), known as the Sagnac effect, is observed in entangled neutrons produced using a spin echo interferometer. Afte…
Multifold paths of neutrons in the three-beam interferometer detected by tiny energy-kick
Hermann Geppert-Kleinrath, Tobias Denkmayr, Stephan Sponar +3
A neutron optical experiment is presented to investigate the paths taken by neutrons in a three-beam interferometer. In various beam-paths of the interferometer, the energy of the…
Twisting Neutral Particles with Electric Fields
Niels Geerits, Stephan Sponar
We demonstrate that spin-orbit coupled states are generated in neutral magnetic spin 1/2 particles travelling through an electric field. The quantization axis of the orbital angula…
Residual error-disturbance uncertainties in successive spin-1/2 measurements tested in matter-wave optics
Bülent Demirel, Stephan Sponar, Georg Sulyok +2
The indeterminacy inherent in quantum measurement is an outstanding character of quantum theory, which manifests itself typically in Heisenberg's error-disturbance uncertainty rela…
Response to `Comment on "Experimental demonstration of a universally valid error-disturbance uncertainty relation in spin measurements" '
Jacqueline Erhart, Stephan Sponar, Georg Sulyok +3
Here, we reply to the comment by Y. Kurihara. We show that the argument by the author is on an improper basis and thus disagree with his opinion.
Tests of Fundamental Quantum Mechanics and Dark Interactions with Low Energy Neutrons -- Extended Version
Stephan Sponar, Rene I. P. Sedmik, Mario Pitschmann +2
Among the known particles, the neutron takes a special position, as it provides experimental access to all four fundamental forces and a wide range of hypothetical interactions. De…
Spin - Rotation Coupling Observed in Neutron Interferometry
Armin Danner, Bülent Demirel, Wenzel Kersten +4
Einstein's theory of general relativity and quantum theory form the two major pillars of modern physics. However, certain inertial properties of a particle's intrinsic spin are inc…
Violation of Heisenberg's error-disturbance uncertainty relation in neutron spin measurements
Georg Sulyok, Stephan Sponar, Jacqueline Erhart +3
In its original formulation, Heisenberg's uncertainty principle dealt with the relationship between the error of a quantum measurement and the thereby induced disturbance on the me…
Kochen-Specker theorem studied with neutron interferometer
Yuji Hasegawa, Katharina Durstberger-Rennhofer, Stephan Sponar +1
The Kochen-Specker theorem theoretically shows evidence of the incompatibility of noncontextual hidden variable theories with quantum mechanics. Quantum contextuality is a more gen…
Engineering of triply entangled states in a single-neutron system
Yuji Hasegawa, Rudolf Loidl, Gerald Badurek +2
We implemented a triply entangled Greenberger-Horne-Zeilinger(GHZ)-like state and coherently manipulated the spin, path, and energy degrees of freedom in a single neutron system. T…
Experimental Test of Tight State-Independent Preparation Uncertainty Relations for Qubits
Stephan Sponar, Armin Danner, Kazuma Obigane +2
The well-known Robertson-Schroedinger uncertainty relations miss an irreducible lower bound. This is widely attributed to the lower bound's state-dependence. Therefore, Abbott \emp…
Experimental demonstration of a universally valid error-disturbance uncertainty relation in spin-measurements
Jacqueline Erhart, Stephan Sponar, Georg Sulyok +3
The uncertainty principle generally prohibits determination of certain pairs of quantum mechanical observables with arbitrary precision and forms the basis of indeterminacy in quan…
Three-Path Quantum Cheshire Cat Observed in Neutron Interferometry
Armin Danner, Niels Geerits, Hartmut Lemmel +3
The paradoxical phenomenon of the quantum Cheshire Cat (qCC) refers to situations where different properties of a particle appear to be localised in different paths of an interfero…
General complex Spin Weak Values obtained in Matter-Wave Interferometer Experiments
Stephan Sponar, Tobias Denkmayr, Hermann Geppert +3
Weak values of the spin operator Sz of massive particles, more precisely neutrons, have been experimentally determined by applying a novel measurement scheme. This is achieved by c…
Experimental test of entropic noise-disturbance uncertainty relations for spin-1/2 measurements
Georg Sulyok, Stephan Sponar, Buelent Demirel +4
Information-theoretic definitions for noise and disturbance in quantum measurements were given in Phys. Rev. Lett. 112, 050401 (2014) and a state-independent noise-disturbance unce…
Direct experimental test of commutation relation via weak value
Richard Wagner, Wenzel Kersten, Armin Danner +3
The canonical commutation relation is the hallmark of quantum theory and Heisenberg's uncertainty relation is a direct consequence of it. But despite its fundamental role in quantu…
Experimental demonstration of direct path state characterization by strongly measuring weak values in a matter-wave interferometer
Tobias Denkmayr, Hermann Geppert, Hartmut Lemmel +4
A novel method was recently proposed and experimentally realized for characterizing a quantum state by directly measuring its complex probability amplitudes in a particular basis u…
Improvement of the polarized neutron interferometer setup demonstrating violation of a Bell-like inequality
Hermann Geppert, Tobias Denkmayr, Stephan Sponar +2
For precise measurements with polarized neutrons high efficient spin-manipulation is required. We developed several neutron optical elements suitable for a new sophisticated setup,…
CANISIUS The Austrian Neutron Spin Echo Interferometer
Niels Geerits, Simon Hack, Lara Brukner +4
The broad band resonant spin echo interferometer, CANISIUS, is presented. CANISIUS is built in a versatile way, such that it can be operated in both a continuous broad band beam or…
Orbital Angular Momentum Generation in Schwinger Scattering from Perfect Quartz
Niels Geerits, Anna-Sophie Berger, Hartmut Lemmel +4
Static electric fields have been suggested as a spin to orbital angular momentum converter in neutrons. Initial calculations showed that the field required to facilitate significan…
Covariant correlation-disturbance and its experimental realization with spin-1/2 particles
Ali Asadian, Florian Gams, Stephan Sponar
We formulate a precise tradeoff relation between correlation and disturbance for sequential -outcome quantum measurements in Hilbert spaces of arbitrary dimension. This relation…
Search for dark energy with neutron interferometry
Hauke Fischer, Christian Käding, Hartmut Lemmel +2
We use previously obtained experimental results by neutron interferometry to effectively constrain the parameter space of several prominent dark energy models. This investigation e…
Neutron optical test of completeness of quantum root-mean-square errors
Stephan Sponar, Armin Danner, Masanao Ozawa +1
One of the major problems in quantum physics has been to generalize the classical root-mean-square error to quantum measurements to obtain an error measure satisfying both soundnes…
Additive Manufactured and Topology Optimized Permanent Magnet Spin-Rotator for Neutron Interferometry Applications
Wenzel Kersten, Laurids Brandl, Richard Wagner +5
In neutron interferometric experiments using polarized neutrons coherent spin-rotation control is required. In this letter we present a new method for Larmor spin-rotation around a…
Violation of a Leggett-Garg inequality using ideal negative measurements in neutron interferometry
Elisabeth Kreuzgruber, Richard Wagner, Niels Geerits +2
We report on an experiment that demonstrates the violation of a Leggett-Garg inequality (LGI) with neutrons. LGIs have been proposed in order to assess how far the predictions of q…
Tight qubit uncertainty relations studied through weak values in neutron interferometry
Andreas Dvorak, Ismaele V. Masiello, Yuji Hasegawa +3
In its original formulation, Heisenberg's uncertainty principle describes a trade-off relation between the error of a quantum measurement and the thereby induced disturbance on the…
Anomalous weak values in a generalized Mach-Zehnder interferometer extracted directly from intensity measurements
Ismaele V. Masiello, Hartmut Lemmel, Andreas Dvorak +2
Weak values provide a powerful framework for characterizing quantum systems. Their experimental extraction conventionally relies on weak conditioned von Neumann measurements, invol…
Phase Vortex Lattices in Neutron Interferometry
Niels Geerits, Hartmut Lemmel, Anna-Sophie Berger +1
A combination of aluminium prisms inserted into a nested loop interferometer is used to generate a neutron phase vortex lattice with significant extrinsic orbital angular momentum,…