Optical preparation of entangled squeezed vacuum states

Jing-Ji Wen, Ming Wang, Hong‐Fu Wang +1 more

Jing-Ji Wen, Kyu-Hwang Yeon, Hong‐Fu Wang +1 more

Amir Karimi, Mohammad Kazem Tavassoly

Changyong Chen, Mang Feng, Kelin Gao

We propose a scheme to generate superposition and entanglement between the mesoscopic squeezed vacuum states by considering the two-photon interaction of $N$ two-level atoms in a cavity with high quality factor, assisted by a strong driving field. By virtue of specific choices of the cavity detuning, a number of multiparty entangled states can be prepared, including the entanglement between the atomic and the squeezed vacuum cavity states and between the squeezed vacuum states and the coherent states of the cavities. We also present how to prepare entangled states and ``Schr\"odinger cats'' states regarding the squeezed vacuum states of the cavity modes. The possible extension and application of our scheme are discussed. Our scheme is close to the reach with current cavity QED techniques.

Carlton M. Caves

Jiazhong Hu, Wenlan Chen, Zachary Vendeiro +3 more

We investigate the generation of entanglement (spin squeezing) in an optical-transition atomic clock through the coupling to an optical cavity in its vacuum state. We show that if each atom is prepared in a superposition of the ground state and a long-lived electronic excited state, and viewed as a spin-1/2 system, then the collective vacuum light shift entangles the atoms, resulting in a squeezed distribution of the ensemble collective spin, without any light applied. This scheme reveals that even an electromagnetic vacuum can constitute a useful resource for entanglement and quantum manipulation. By rotating the spin direction while coupling to the vacuum, the scheme can be extended to implement two-axis twisting resulting in stronger squeezing.