Quantum Entanglement Producing and Precision Measurement with Spinor BECs

[摘要] In this dissertation we focused on some quantum states with strong entanglement and robustness to noise. We constructed a spinor BEC Hamiltonian which has already been realized in experiment with several different kinds of atoms and proposed an adiabatic passage method to produce the maximal entangled Dicke state.We also analyzed the entanglement behavior of the Dicke state under various noises and demonstrate its use in high precision measurement experiment. We introduce a new class of quantum many-particle entangled states, called the Dicke squeezed (or DS) states, which can be used to improve the precision in quantum metrology beyond the standard quantum limit. We show that the enhancement in measurement precision is characterized by a single experimentally detectable parameter, called the Dicke squeezing, which also bounds the entanglement depth for this class of states. The measurement precision approaches the ultimate Heisenberg limit as the Dicke squeezing parameter attains the minimum in an ideal Dicke state. Compared with other entangled states, we show that the Dicke squeezed states are more robust to decoherence and give better measurement precision under typical experimental noise.On the other hand, we explore other choices of precision measurement with spin squeezed states. Spin squeezed states have strong manybody entanglement and are good candidates to be used in quantum metrology. A robust squeezing parameter is proposed to characterize the experimental phase measurement precision for spin squeezed states. The behavior of this parameter under various experimental noises is compared with other parameters in the history and it is shown to have better performance.Finally we present a scalable implementation scheme for Boson sampling using local transverse phonon modes in trapped ion system, which is a promising model for quantum computers.

[发布机构] University of Michigan

[效力级别] Physics

[关键词] Quantum information and quantum computation;Physics;Science;Physics