Experimental method measures quantum coherence, the ability of being in two states at once

Researchers from the UAB Department of Physics and the Indian Institute of Science, Education and Research Kolkata propose a new way of measuring the robustness of the quantum coherence of a superimposed state. The method is based on the measurement of the visibility of interference fringes, a figure formed by alternate dark and intense stripes similar to that of a zebra, produced when two coherent states coincide.

According to UAB researcher Andreas Winter, "The existence of quantum superpositions is at the heart of the non-classical nature of quantum physics. It manifests itself by producing interference patterns in interferometric experiments. We show that each visibility parameter of the interference pattern, such as the difference between maximums and minimums in intensity, gives rise to a measure of coherence. The study thus connects the recently burgeoning, but hitherto rather abstract resource theory of coherence, to concrete and physically relevant observations."

The scientists, experts in information quantum theory, study the intrinsic properties of quantum mechanics such as entanglement, uncertainty, superposition, indeterminism and interference, to be used as resources in quantum information processing, the foundation of future quantum computers.