A quantum resonator that is large enough to be seen with the naked eye and that has about one trillion atoms (way above the previous record of just some 60 atoms) has been created by researchers of the University of California.
To make it behave in quantum ways, they first had to cool the object to a thousandth of degree above absolute zero, which is the temperature of its ground state, then they introduced a single quantum of energy (a phonon) and were able to measure the quantum state, meaning that the resonator was in two alternative states at the same time, as all quantum objects, such as electrons, are normally, but unlike any other massive objects known to date (as these are too much affected by the environment, losing their spooky quantum properties)
This achievement has groundbreaking implications for both theoritecal physics and practical applications such as the much fabled quantum computing.
More details at BBC.
A. D. O'Connell et al. Quantum ground state and single-phonon control of a mechanical resonator. Nature, 2010. Pay per view.