New Interferometer Tests Quantum Mechanics and Gravity Interaction on Single Atoms

Testing Fundamental Theories

Physicists have long theorized about the effect of free fall on a quantum wave. If these theories are incorrect, it would indicate a direct contradiction between quantum mechanics and Einstein's theory of gravity. The challenge has been the inability to build an interferometer capable of performing the necessary measurements.

Novel Interferometer Design

A team led by Ron Folman at Ben-Gurion University of the Negev, in collaboration with researchers from Germany, the UK, and the US, including Nobel laureate Roger Penrose, has successfully constructed a new interferometer. This device allows a single atom to follow two simultaneous paths: one involving free fall and another where it remains stationary. Both paths converge at the same point and time, enabling the measurement of how free fall impacts the atom's wave-like properties.

Quantum Wave Properties

Quantum mechanics posits that every object, regardless of size, also behaves as a wave. The wave nature of an atom is observable when it is cooled to near absolute zero, a capability that became available in the late 1990s. The experiment measures the 'phase' of the wave, which indicates its position within its oscillation (e.g., peak or trough).

Measurement Challenges

Measuring a wave's phase directly is not possible; it can only be determined through comparison. This requires splitting a single particle into two trajectories and then recombining them to observe interference patterns. This principle is similar to the double-slit experiment, where interference patterns reveal the phase of particles.