Time-of-flight quantum tomography of an atom in an optical tweezer

A single particle trapped in a harmonic potential can exhibit rich motional quantum states within its high-dimensional state space. Quantum characterization of motion is key, for example, in controlling or harnessing motion in trapped ion and atom systems or observing the quantum nature of the vibrational excitations of solid-state objects. Here we show that the direct measurement of position and momentum can be used for quantum tomography of motional states of a single trapped particle. We obtain the momentum of an atom in an optical tweezer via time-of-flight measurements, which, combined with trap harmonic evolution, grants us access to all quadrature distributions. Starting with non-classical motional states of a trapped neutral atom, we demonstrate the Wigner function negativity and coherence of non-stationary states. Our work will enable the characterization of the complex neutral atom motion that is of interest for quantum information and metrology, and for investigations of the quantum behaviour of massive levitated particles. A tomography protocol that exploits the control offered by optical tweezers allows the reconstruction of motional states of a single trapped atom. This has implications for the study of non-classical states of massive trapped and levitated particles.

Automated summary

This study demonstrates the measurement and reconstruction of quantum mechanical states through the direct measurement of position and momentum. By using optical tweezers to measure the momentum and trap harmonic evolution, we have successfully observed non-classical motional states and demonstrated some of their quantum properties. This research is important for quantum information, metrology, and the study of quantum behavior in massive levitated particles.