Atomic "bomb testing": The Elitzur-Vaidman experiment violates the Leggett-Garg inequality

Robens, Carsten; Alt, Wolfgang; Emary, Clive; Meschede, Dieter; Alberti, Andrea

Abstract

Elitzur and Vaidman have proposed a measurement scheme that, based on the quantum superposition principle, allows one to detect the presence of an object—in a dramatic scenario, a bomb—without interacting with it. It was pointed out by Ghirardi that this interaction-free measurement scheme can be put in direct relation with falsification tests of the macro-realistic worldview. Here we have implemented the “bomb test” with a single atom trapped in a spin-dependent optical lattice to show explicitly a violation of the Leggett–Garg inequality—a quantitative criterion fulfilled by macro-realistic physical theories. To perform interaction-free measurements, we have implemented a novel measurement method that correlates spin and position of the atom. This method, which quantum mechanically entangles spin and position, finds general application for spin measurements, thereby avoiding the shortcomings inherent in the widely used push-out technique. Allowing decoherence to dominate the evolution of our system causes a transition from quantum to classical behavior in fulfillment of the Leggett–Garg inequality.

Citation

Robens, C., Alt, W., Emary, C., Meschede, D., & Alberti, A. (2018). Atomic "bomb testing": The Elitzur-Vaidman experiment violates the Leggett-Garg inequality. In Exploring the World with the Laser: Dedicated to Theodor Hänsch on his 75th Birthday (141-157). Springer International Publishing. https://doi.org/10.1007/978-3-319-64346-5_10

• Acceptance Date: Jan 2, 2018
• Online Publication Date: Jan 3, 2018
• Publication Date: Jan 2, 2018
• Deposit Date: Jun 27, 2018
• Publicly Available Date: Jun 29, 2018
• Pages: 141-157
• Book Title: Exploring the World with the Laser: Dedicated to Theodor Hänsch on his 75th Birthday
• Chapter Number: 11
• ISBN: 9783319643458; 9783319643465
• DOI: https://doi.org/10.1007/978-3-319-64346-5_10
• Public URL: https://hull-repository.worktribe.com/output/897392
• Publisher URL: https://link.springer.com/chapter/10.1007%2F978-3-319-64346-5_10
• Contract Date: Jun 29, 2018