Research

Research Projects

Strongly coupled Cavity QED and the precision measurement of single atoms

The primary objective of this research is to study atom-quantized field interactions in regions of confined space, in which single atom is strong coupled with the light field. Currently far off resonance optical dipole traps, either in blue trap or red trap, have been used to control the atoms and the internal state of the single atom, known as the single qubit, can be well controlled with long coherent time. Through the low loss micro cavity, the interaction between light field and atoms can be implemented, thus the radiant properties of atom and properties of quantum entanglement and nonclassical state generation based on this strongly coupled cavity QED system can be investigated.

Cavity QED based on microtoroidal resonator and nanofibre for quantum information

Strong-coupled cavity quantum electrodynamics (Cavity QED) system with single emitter has been a wonderful tool to explore fundamental problems of many quantum systems, precision measurements, quantum metrology and quantum information processing. Microtoroidal resonators with whispering-gallery-mode and high Q factor coupled with tapered nanofiber make cavity QED system possible to be smaller and easier to be integrated，which can not only demonstrate and explain many new quantum problems with multi-cavities or multi-atoms， but also become a candidate for quantum information and quantum internet.

Manipulation of Single Neutral Atoms

In recent years, quantum information processing (QIP) has attracted intense attention . The basic unit for QIP is a qubit encoded in an isolated two-level quantum system on which one can perform arbitrary single-qubit unitary operations. Our quantum systems are trapped neutral atoms. Qubits encoded in the ground states of laser-trapped neutral atoms are free of interactions with phonons and they are insensitive to external electric field. More importantly the stable and clean ground states provide long coherence time in room temperature. On the other hand, strong interaction between neutral atoms and external electromagnetic field provides convenient ways to manipulate both internal and external atomic states. Single atom can be confined in a small region and cooled to its vibrational ground state by means of laser cooling, faroff resonant trap (FORT) and sideband cooling. Other techniques of optical pumping, Raman process, microwave interaction and resonant fluorescence provide methods for initializing, rotating and reading the atomic qubit with high accuracy. All these developments and the related techniques have helped to bring about the single neutral atoms being a powerful candidate for QIP.

Polarized-squeezed state quantum magnetometer system

Squeezed states of optical fields are important quantum resources for the research of light-atom interaction, quantum precision measurement and information storage. We aim to improve the sensitivity of the weak magnetic field measurement by using a low frequencies polarization-squeezed probe light tuned the Cs atomic D2 transition line. We prepare squeezed vacuum corresponding to the Cs atomic D2 line from a below-threshold optical parametric oscillator (OPO), and generate polarization-squeezed light using the linear interference method, which will be applied to ultra sensitive magnetic field measurement.

	Strongly coupled Cavity QED and the precision measurement of single atoms The primary objective of this research is to study atom-quantized field interactions in regions of confined space, in which single atom is strong coupled with the light field. Currently far off resonance optical dipole traps, either in blue trap or red trap, have been used to control the atoms and the internal state of the single atom, known as the single qubit, can be well controlled with long coherent time. Through the low loss micro cavity, the interaction between light field and atoms can be implemented, thus the radiant properties of atom and properties of quantum entanglement and nonclassical state generation based on this strongly coupled cavity QED system can be investigated.
	Cavity QED based on microtoroidal resonator and nanofibre for quantum information Strong-coupled cavity quantum electrodynamics (Cavity QED) system with single emitter has been a wonderful tool to explore fundamental problems of many quantum systems, precision measurements, quantum metrology and quantum information processing. Microtoroidal resonators with whispering-gallery-mode and high Q factor coupled with tapered nanofiber make cavity QED system possible to be smaller and easier to be integrated，which can not only demonstrate and explain many new quantum problems with multi-cavities or multi-atoms， but also become a candidate for quantum information and quantum internet.
	Manipulation of Single Neutral Atoms In recent years, quantum information processing (QIP) has attracted intense attention . The basic unit for QIP is a qubit encoded in an isolated two-level quantum system on which one can perform arbitrary single-qubit unitary operations. Our quantum systems are trapped neutral atoms. Qubits encoded in the ground states of laser-trapped neutral atoms are free of interactions with phonons and they are insensitive to external electric field. More importantly the stable and clean ground states provide long coherence time in room temperature. On the other hand, strong interaction between neutral atoms and external electromagnetic field provides convenient ways to manipulate both internal and external atomic states. Single atom can be confined in a small region and cooled to its vibrational ground state by means of laser cooling, faroff resonant trap (FORT) and sideband cooling. Other techniques of optical pumping, Raman process, microwave interaction and resonant fluorescence provide methods for initializing, rotating and reading the atomic qubit with high accuracy. All these developments and the related techniques have helped to bring about the single neutral atoms being a powerful candidate for QIP.
	Polarized-squeezed state quantum magnetometer system Squeezed states of optical fields are important quantum resources for the research of light-atom interaction, quantum precision measurement and information storage. We aim to improve the sensitivity of the weak magnetic field measurement by using a low frequencies polarization-squeezed probe light tuned the Cs atomic D2 transition line. We prepare squeezed vacuum corresponding to the Cs atomic D2 line from a below-threshold optical parametric oscillator (OPO), and generate polarization-squeezed light using the linear interference method, which will be applied to ultra sensitive magnetic field measurement.

Research Projects