Physicists from the University of Warsaw believe that they may have achieved “the impossible.” They were able to create a hologram of a single particle of light. Previously, scientists believed that the fundamental laws of physics did not allow this, and to that end, their breakthrough allows physicists to further study quantum holography (which may give us a new way to peer into the heart of quantum phenomena).

To break this down a bit, holography takes advantage of classical interference, a phenomenon where two waves meet and form a new wave. However, property of photons called “phases” does not allow classical interference because the phases constantly fluctuate. The physicists instead used quantum interference wherein the photons’ wave functions interact.

Wave function is a fundamental concept in quantum mechanics and the core of the Schrödinger equation, one of the most important principles of quantum mechanics.

Two of the researchers, Radoslaw Chrapkiewicz and Michal Jachura, noticed two-photon interference while they were filming the behavior of pairs of photons. Two-photon interference occurs when pairs of distinguishable photons act randomly when entering a beam splitter while non-distinguishable photons exhibit either being reflected or transmitted.

Chrapkiewicz said that their experiment became their inspiration to find out if two-photon interference could be used just like classical interference in holography to gain further information about a photon in an unknown state by using a photon at a known state.

The result of their experiment is a huge step towards understanding the fundamentals of quantum mechanics. It allows scientists to further observe and gain more valuable insight regarding the phase of a photon’s wave function.

“Our experiment is one of the first allowing us to directly observe one of the fundamental parameters of photon’s wave function – its phase – bringing us a step closer to understanding what the wave function really is,” Jachura said.

The scientists are hoping that they could use this method to create holograms of complex objects in the future.