Groundbreaking “Dark” Nanoparticle Experiment Set To Unveil Mysteries of the Macroscopic Quantum World

Physics Quantum Mechanics

 A glass bead with nanoscale dimensions that is evolving in a potential generated by magnetic or electrostatic forces reaches a macroscopic quantum superposition state. Thank you, Helene Hainzer

Making a nanoscale-sized glass bead exhibit quantum effects at macroscopic scales.

It’s still unclear how to distinguish between the quantum world and the real world. When an object cools its motion to absolute zero via a quantum transformation, its localization becomes more intense with increasing size.


Under the direction of Oriol Romero-Isart, researchers from the Department of Theoretical Physics at the University of Innsbruck and the Institute for Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences (ÖAW) propose an experiment in which an optically levitated nanoparticle cools to its ground state and evolves in a non-optical (“dark”) potential generated by electrostatic or magnetic forces. It is anticipated that a macroscopic quantum superposition state would be produced quickly and consistently by this evolution in the dark potential.

Overcoming Challenges in Quantum Experiments

A glass sphere the size of a nanometer can be cooled to its motional ground state by laser light. Left alone, attacked by air molecules and scattering incoming light, such glass spheres quickly heat up and depart the quantum realm, restricting quantum control. The researchers suggest letting the sphere evolve in complete darkness, without the use of light, using only non-uniform electrostatic or magnetic forces, to prevent this. This evolution lifts the severe localization and imprints unambiguously quantum properties, yet it proceeds quickly enough to avoid heating by random gas molecules.


Addressing Practical Challenges and Future Prospects

How this concept gets beyond the practical difficulties of these kinds of tests is also covered in the recent study published in Physical Review Letters. Among these difficulties are the requirement for quick experimental runs, the necessity to use laser light as little as possible to prevent decoherence, and the speedy repetition of experimental runs using the same particle. To lessen the effects of low-frequency noise and other systematic mistakes, several factors are essential.
states of superposition.
With the experimental partners in Q-Xtreme, an EU-funded ERC Synergy Grant project, this proposition has been thoroughly examined. “Our protocol with thermal particles in the classical regime should be tested soon, as it is in line with current developments in their labs. This will be very helpful to measure and minimize sources of noise when lasers are off,” the theory team of Oriol Romero-Isart says. “Although the ultimate quantum experiment will inevitably be difficult, we think it should be possible because it satisfies all the requirements for creating these macroscopic quantum superposition states.”
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