Characterization of the quantum-state in hot atomic vapour

Quantum-state tomography is a crucial ingredient in quantum-state engineering and computing. From the point of view of these fields, it is important to determine a state of a photon as well as atoms. While the first is commonly used for quantum-information transmission, the latter offers the possibility to manipulate the state by external magnetic and electromagnetic fields. Atomic gasses are also among the most promises candidates for quantum-information storage. Typically, this task is performed in cold atomic clouds, where various relaxation processes are mitigated, yet hot atomic vapours also offer various advantages, like the simplicity of ensemble preparing (lack of cooling apparatus). During presentation, I will describe a method enabling measurements of collective quantum-state in hot atomic vapours via weak nondemolition measurement performed by off-resonant laser light. Quantum-state estimation is performed by measurement of Faraday rotation of transmitted light, while the external optical and magnetic field are used to control over the evolution of the atomic state.