Spin-orbit coupled Bose-Einstein condensates in a cavity


It is well known that the interplay of Coulomb interaction among particles in electronic systems and quantum statistics leads to various orderings of spins in quantum mechanical ground states of the system leading to the quantum theory of magnetism. Since the outbreak of various trapping and cooling methods, neutral ultra cold atoms have become a playground for testing many of our understandings in physics. They provide a unique possibility for mimicking real solid state systems of charged electrons under much more controlled experimental situation . With the experimental success of synthesis of spin like degrees of freedom ( dubbed as pseudo-spin ), such ultra cold atoms provide a new vista to the realization of various quantum magnetic orders. However, even in case of ultra cold atoms, the detection of such spin-orderings is still quite a challenging task. In this work the authors have shown that the detection of such (pseudo-)spin orderings in ultra cold atomic systems can be made much simpler and versatile by placing them in an optical cavity (see the Figure ) and using the quantum properties of light in such cavity. The standing wave of light (the optical lattice) generated inside such cavity with highly polished mirrors need to be treated quantum mechanically when this standing wave interacts strongly with the atoms. The photons (quantized light) decaying out of the cavity after making several round trips are collected by a camera and this count is monitored with different pump laser strengths (also known as cavity spectrum). The work shows that such photon count is characteristic of the spin-arrangement of ultra cold atoms inside the cavity (see Figure) and can reveal various quantum magnets made out of ultra-cold atoms, such as ferromagnet, anti-ferromagnet, etc. . If the suggested system can be experimentally realized, the detection of spin-arrangements in cold atom system can become more simplified and opens new possibilities for quantum simulation with cold atoms.

Contact details: 

Bikash Padhi and Sankalpa Ghosh

Department of Physics