Leggett-Garg tests for macrorealism: interference experiments and the simple harmonic oscillator

• URL: http://arxiv.org/abs/2009.03856v4
• Date: Sun, 21 Mar 2021 15:28:42 GMT
• Title: Leggett-Garg tests for macrorealism: interference experiments and the simple harmonic oscillator
• Authors: J.J.Halliwell, A.Bhatnagar, E.Ireland, H.Nadeem and V.Wimalaweera
• Abstract summary: Leggett-Garg tests for macrorealism were originally designed to explore quantum coherence on the macroscopic scale. We show that LG violations are always accompanied by destructive interference. We also exhibit examples of some surprising relationships between LG inequalities and NSIT conditions that do not exist for dichotomic variables.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: Leggett-Garg (LG) tests for macrorealism were originally designed to explore quantum coherence on the macroscopic scale. Interference experiments and systems modelled by harmonic oscillators provide useful examples of situations in which macroscopicity has been approached experimentally and are readily turned into LG tests for a single dichotomic variable Q. Applying this approach to the double-slit experiment in which a non-invasive measurement at the slits is included, we exhibit LG violations. We find that these violations are always accompanied by destructive interference. The converse is not true in general and we find that there are non-trivial regimes in which there is destructive interference but the two-time LG inequalities are satisfied which implies that it is in fact often possible to assign (indirectly determined) probabilities for the interferometer paths. Similar features have been observed in recent work involving a LG analysis of a Mach-Zehnder interferometer and we compare with those results. We extend the analysis to the triple-slit experiment again finding LG violations, and we also exhibit examples of some surprising relationships between LG inequalities and NSIT conditions that do not exist for dichotomic variables. For the simple harmonic oscillator, we find an analytically tractable example showing a two-time LG violation with a gaussian initial state, echoing in simpler form recent results of Bose et al (Phys. Rev. Lett. 120, 210402 (2018)).

Related papers

• Violation of the Leggett-Garg Inequality for Dynamics of a Bose-Einstein Condensate in a Double-Well Potential [0.0]
  We investigate the violation of the Leggett-Garg inequality (LGI) for the system of bosons in a double-well potential. Our analysis reveals that the LGI is violated due to Josephson oscillations, while it remains unviolated in the strong coupling regime.
  arXiv  Detail & Related papers  (2024-07-07T08:53:27Z)
• Test of transient deviations from Quantum Mechanics in Bell's experiment [41.94295877935867]
  The conflict between Quantum Mechanics (QM) and Local Realism is most noticeable in the correlations observed between distant regions of a spatially spread entangled state. It has been hypothesized that transient deviations (from the values predicted by QM) may be observed if the correlations are measured in a time shorter than L/c. We present the results of such a test performed on a specially designed optical Bell setup with a distance between stations up to 24 m in straight line.
  arXiv  Detail & Related papers  (2024-04-15T13:01:30Z)
• Large violation of Leggett-Garg inequalities with coherent-state projectors for a harmonic oscillator and chiral scalar field [0.0]
  We investigate violations of Leggett-Garg inequalities (LGIs) for a harmonic oscillator and a (1+1)-dimensional chiral scalar field with coherent-state projectors. We find that the vacuum and thermal states violated the LGIs by evaluating the two-time quasi-probability distribution function. We also find a violation of the LGIs for the local mode of a quantum chiral scalar field by constructing a coherent-state projector.
  arXiv  Detail & Related papers  (2024-01-19T13:47:25Z)
• Doubly Stochastic Models: Learning with Unbiased Label Noises and Inference Stability [85.1044381834036]
  We investigate the implicit regularization effects of label noises under mini-batch sampling settings of gradient descent. We find such implicit regularizer would favor some convergence points that could stabilize model outputs against perturbation of parameters. Our work doesn't assume SGD as an Ornstein-Uhlenbeck like process and achieve a more general result with convergence of approximation proved.
  arXiv  Detail & Related papers  (2023-04-01T14:09:07Z)
• Test of macroscopic realism with coherent light [7.43265504719989]
  We report the LGI violation of path observable in a composite interference experiment with coherent light. Experiment results confirm the occurrence of destructive interference providing per se as evidence of macro-realism violation.
  arXiv  Detail & Related papers  (2023-02-17T10:56:19Z)
• Leggett-Garg violations for continuous variable systems with gaussian states [0.0]
  We seek LG violations for measurements of a dichotomic variable $Q = textrmsign(x)$. An exploration of parameter space reveals significant regimes in which the two-time LG inequalities are violated. We exploit the continuous nature of the underlying position variable and analyse the relevant quantum-mechanical currents.
  arXiv  Detail & Related papers  (2022-11-18T15:30:48Z)
• Experimental Higher-Order Interference in a Nonlinear Triple Slit [50.591267188664666]
  We experimentally show that nonlinear evolution can in fact lead to higher-order interference. Our work shows that nonlinear evolution could open a loophole for experiments attempting to verify Born's rule by ruling out higher-order interference.
  arXiv  Detail & Related papers  (2021-12-13T19:05:38Z)
• Leggett-Garg tests for macrorealism in the quantum harmonic oscillator and more general bound systems [0.0]
  We present a simple method to calculate the temporal correlation functions appearing in the LG inequalities for any bound system. We find substantial regions of parameter space in which the LG inequalities at two, three and four times can each be independently violated or satisfied. We also show that two-time LG violations in a gaussian state are readily found if the dichotomic variable at one of the times is taken to be the parity operator.
  arXiv  Detail & Related papers  (2021-09-07T14:27:21Z)
• Quantum asymmetry and noisy multi-mode interferometry [55.41644538483948]
  Quantum asymmetry is a physical resource which coincides with the amount of coherence between the eigenspaces of a generator. We show that the asymmetry may emphincrease as a result of a emphdecrease of coherence inside a degenerate subspace.
  arXiv  Detail & Related papers  (2021-07-23T07:30:57Z)
• Towards probing for hypercomplex quantum mechanics in a waveguide interferometer [55.41644538483948]
  We experimentally investigate the suitability of a multi-path waveguide interferometer with mechanical shutters for performing a test for hypercomplex quantum mechanics. We systematically analyse the influence of experimental imperfections that could lead to a false-positive test result.
  arXiv  Detail & Related papers  (2021-04-23T13:20:07Z)
• Assessment of weak-coupling approximations on a driven two-level system under dissipation [58.720142291102135]
  We study a driven qubit through the numerically exact and non-perturbative method known as the Liouville-von equation with dissipation. We propose a metric that may be used in experiments to map the regime of validity of the Lindblad equation in predicting the steady state of the driven qubit.
  arXiv  Detail & Related papers  (2020-11-11T22:45:57Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.