Precision measurements using squeezed spin states via two-axis countertwisting interactions

A Superradiant Laser and Spin Squeezed States: Collective Phenomena in a Rubidium Cavity QED System for Enhancing Precision Measurements

Precision measurements of spin interactions with high density atomic vapors

Polarized atomic vapors can be used to detect fields interacting with a spin. Recent advances have extended the sensitivity of atomic magnetometers to a level favorable for fundamental physics research, and in many cases the sensitivity approaches quantum metrology limits. In this thesis, we present a high density atomic K-He comagnetometer, which features suppressed sensitivity to magnetic fie...

Control of Squeezed Phonon and Spin States

In this paper we analyze the quantum control of squeezed states of harmonic oscillators as well as spin squeezing and its relationship to quadrature squeezed states of other bosonic fields. Squeezing provides a method for reducing noise below the quantum limit and provides an example of the control of under-actuated control systems in the stochastic and quantum context. We consider also the int...

Spin squeezing and pairwise entanglement for symmetric multiqubit states

We show that spin squeezing implies pairwise entanglement for arbitrary symmetric multiqubit states. If the squeezing parameter is less than or equal to 1, we demonstrate a quantitative relation between the squeezing parameter and the concurrence for the even and odd states. We prove that the even states generated from the initial state with all qubits being spin down, via the one-axis twisting...

Deterministic Secure Communications using Two-Mode Squeezed States

We propose a scheme for quantum cryptography that uses the squeezing phase of a two-mode squeezed state to transmit information securely between two parties. The basic principle behind this scheme is the fact that each mode of the squeezed field by itself does not contain any information regarding the squeezing phase. The squeezing phase can only be obtained through a joint measurement of the t...