Investigation of entangled spin state between two Rb⁸⁵ atoms in an optical tweezer

Spin-changing collisions have been widely used to generate entanglement in many-body systems. They have also been utilized to entangle two q-bits in a zero temperature experiment. However, generating entanglement at a higher temperature may pave the way to the development of practical quantum technologies. Recent research shows that the spin-changing collisions of two thermal atoms initially prepared in the F=2, m=0 ground state lead to strong spin pair correlations between the magnetic sub-states m=+1 and m=-1. These correlations can be a classical mixture of the initial spin states and the entangled spin state. Here, we use hot spin-changing collisions to generate entanglement between two rubidium-85 atoms trapped in an optical tweezer. We investigate the generation of the entangled state by driving stimulated Raman transition between the two magnetic sub-states. The result shows that spin-changing collisions generate the entanglement. We measure the lifetime of the entanglement as this is an important characteristic for a further use in quantum applications. Moreover, we perform a Ramsey-type experiment to demonstrate that the generated entanglement can be employed to make an entanglement enhanced magnetic field measurement. To further improve the efficiency of the entanglement generation, the experimental parameters such as bias magnetic field, and depth of the optical tweezer can be optimized.