Experimental non-classicality of an indivisible quantum system.

Area of Science:

• Quantum Physics
• Foundations of Quantum Mechanics

Background:

• Classical physics assumes properties are well-defined, unlike quantum theory (Heisenberg uncertainty principle).
• Non-contextual hidden-variable models propose pre-defined properties, independent of measurement.
• Previous experiments with qubits showed conflicts between quantum mechanics and these classical models.

Purpose of the Study:

• To experimentally test non-contextual theories using the simplest indivisible quantum system: a single qutrit.
• To demonstrate a fundamental incompatibility between quantum mechanics and classical physics that does not rely on entanglement.

Main Methods:

• Experimentation with single photonic qutrits.
• Testing a Bell-type inequality derived by Klyachko, Can, Binicioğlu, and Shumovsky.
• Analyzing measurement outcomes to identify violations of the inequality.

Main Results:

• Observed a violation of the Klyachko-Can-Binicioğlu-Shumovsky inequality using single photonic qutrits.
• Experimental results provide evidence against the existence of joint probability distributions for all possible measurements.
• The observed violation cannot be attributed to entanglement, as the system is indivisible.

Conclusions:

• The experiment confirms the incompatibility of quantum mechanics with non-contextual hidden-variable theories.
• Results highlight a fundamental departure from classical physics, independent of entanglement.
• The findings underscore the non-classical nature of quantum systems, even at the simplest level.