Macroscopic Quantum Superpositions

2026-07-22

Do the laws of quantum physics hold for massive objects of arbitrary size? Q-Xtreme will address this very important question by testing the quantum superposition principle at unprecedented macroscopic scales: we will place a levitated object in two locations at once, separated by a distance comparable to its size. Experimental confirmations of macroscopic quantum superpositions started as early as 1927, using electrons, and have today reached the size of organic molecules containing thousands of atoms. Q-Xtreme will bring macroscopic quantum physics to an entirely new level by preparing macroscopic quantum superpositions of objects containing billions of atoms, pushing current state-of-the-art by at least five orders of magnitude in mass.  This goal will be achieved by using a radically new approach: quantum controlling the center-of-mass motion of a levitated nanoparticle (a solid-state object of few hundred nanometers) in ultra-high vacuum by using optical, electrical and magnetic forces. Q-Xtreme requires cutting-edge expertise in photonics, nanotechnology, optoelectronics, and quantum technology, which this Synergy Group uniquely combines. The achievements of Q-Xtreme are only possible by the combined proficiency in both fundamental science and engineering of this Synergy Group.  The implications of Q-Xtreme are far-reaching. Testing the quantum superposition principle at unprecedented mass regimes opens the door to experimentally study the interplay of quantum physics and gravity, as well as dark matter and dark energy models. These macroscopic quantum superpositions will also give rise to ultrahigh sensing accuracies, with applications in inertial force sensing, measurements of short-range interactions and gravitational physics.

Spain

2025-10-01