South Korean researchers have invented a new measure to quantify macroscopic quantum superpositions based on phase-space structures of quantum states.

A team led by Professor Jeong Hyun-seok at Seoul National University says the “measure simultaneously quantifies two different kinds of essential information for a given quantum state in a harmonious manner.” Those are “the degree of quantum coherence and the effective size of the physical system that involves the superposition.”

The principle of superposition claims that while we do not know what the state of any object is, it is actually in all possible states simultaneously because the measurement itself causes the object to be limited to a single possibility.

Whether superposition can be observed in the real world and not only in the atomic world has been a big challenge for physicists.

The finding is published in the Physical Review Letters of the American Physical Society.