Quantum manipulation and quantum control pave a new path to approach the fundamentals of quantum mechanics and inspire many applications using quantum physics. In this talk, I will review a few recent demonstrations of manipulating the quantum states in many-body system at the single-particle resolution, exploring the new regime of quantum manipulations.

We experimentally realized the first demonstration of all-optical transistor at the single photon level in the cavity QED system with a transistor gain of 400. By applying this scheme to an all-optical circuit, it could realize photon logic gate at the single-photon level. With a similar system, we also proposed a pioneer method to generate an arbitrary entangled state in the atomic system, just by detecting one single photon.

Then I will switch gears and present the ongoing experiment that enables non-trivial spin-ordering state of two-component Bosons in optical lattice. By adiabatically increasing the interspecies interactions, a gapped phase called spin Mott phase is adiabatically ramped to a non-gapped state called xy-ferromagnetic phase. And the bosonic system are adiabatically cooled to picokelvin temperatures which allow the observation of magnetic ordering via superexchange in optical lattices. Combining with the technique of quantum microscope, we can provide a powerful platform to explore the versatile behaviors of new quantum matters.

At the end, a briefly introduction of the experimental realization of all-laser cooling to the quantum degenerate will be presented. This will be a powerful tool to engineer new quantum matter in ultracold atom systems.