Manipulation And Noise Analysis Of Photonic Polarization State

Quantum information science is a comprehensive subject combining quantum physics,computer science and information science.Recent years,the experiments in quantum information processing base on many systems have substantial developments,including trapped ions,superconducting quantum circuits,ultracold atoms,photons.Photons,as one of them,are not easy to decoherence but easy to preparation and manipulation.Moreover,photons are the natural flying qubits,which plays an indispensable role in quantum communication.Investigations about manipulation and evolution of photons is key components in optical quantum information processing.In the research about optical quantum information,the high-speed control of photonic state is important to achieve high quantum communication rate.Utilizing the electro-optical effect,peoples realized light modulators above 100 GHz,which have been used in for classical light communication,generation and characterization of optical frequency comb.In the domain of quantum optics,electro-optical modulators combined with commercial radio frequency device can also provide coherent highspeed manipulation of photonic state.To implement scalable quantum information processing device,we must overcome the decoherence induced by the coupling between quantum system and environment.At present,peoples developed many methods to endure decoherence,including quantum error correction code,dynamical decoupling and decoherence-free space(DFS).DFS exploits the symmetry in the noisy interaction,has the advantage of inherently coherence preserving ability.The investigation of the system-environment interaction can help people design concise and effective scheme to overcome decoherence.This dissertation mainly includes the following contents:1.The introduction chapter introduces the research background,related concepts and research progress,including quantum information science,commonly used optical components,interferometers.2.The second chapter introduces our scheme to achieve high speed manipulation of photon polarization based on commercial electro-optical modulation.We experimental demonstrated arbitrary single qubit phase gate in polarization encoded photons based on our scheme.3.The second chapter introduces the quantum walk experiments based on our polarization control scheme.We using high speed arbitrary waveform generator to apply different modulation signals at photons in different time bins,and realized position dependent coin in quantum walk.We use gated single photon detectors to characterize the distribution and entanglement entropy after quantum walk.We adopt the subspace quantum state reconstruction and semidefinite optimization method to estimate the low bound of the purity of quantum state after quantum walk,which proves the photon coherence is preserving in our quantum walk.4.The fourth chapter presents a theoretical study of the properties of single mode multi photon states in Pauli noise.We adopt the normalized linear entropy to charactering the quantum state purity after noise channel.In comparison to single photon states,multiphoton states cannot always evolve to maximal mixed state.And we fine multiple decoherence free states and decoherence free subspaces,the information encoded in these spaces cannot be destroyed in noise channel.These results mean that multiphoton state has the ability to preserving coherence in noises.The analysis can also be generalized to the other bosonic quantum system.