| Light is an important physical system for experimental research on quantum information.On one hand,photons themselves can be used as photonic qubits.It includes the heralded single-photon sources based on spontaneous parametric down conversion and the deterministic single-photon sources based on solid-state systems,etc.The polarization,path,and orbital angular momentum of photons can all be encoded as qubits for experimental research in quantum fundamental physics.On the other hand,photons can assist in detecting and manipulating the qubits of other systems,such as trapped ions,semiconductor quantum dots,superconducting circuits,ultracold atoms,solid-state color center spin,and other physical qubits.For the solid-state color center spin systems,photons play an important role in assisting in the detection of solid-state spin energy-level structure and coherent manipulation.During my graduate career,my main work was to carry out experimental research on quantum information using photonic qubits,and to use photons-assisted methods to detect solid-state spin structure and demonstrate coherent manipulation.The main research results in this thesis are as follows:1.We successfully realized the weak-value amplification under non-unitary evolution by using photonic qubits and the spatial light modulator,which proves the advantages of non-unitary evolution over unitary evolution in parameter estimation.High-sensitivity metrology plays an important role in parameter estimation,and weak-value amplification is a significant tool to enhance sensitivity.However,the efficiency of weak-value amplification is always affected by the postselection probability and meter loss.We designed the device for weak interaction that realized the non-unitary evolution based on the spatial light modulator and applied the weak-value amplification of non-unitary evolution.The weak-value amplification of non-unitary evolution can achieve nearly 9-fold as efficient as that of unitary evolution experimentally under specific settings.We used the photon pairs generated by spontaneous parametric down conversion as the light source which possesses a high signal-to-noise ratio and then demonstrated the superiority of non-unitary evolution in weak-value amplification.We provided an experimental scheme of weak interaction for different forms of non-unitary evolution and it possesses the potential to be combined with other techniques for higher effi ciency.2.A PT symmetric quantum simulator with a recycling-structure was constructed for the first time using photonic qubits.The quantum dynamics characteristics of state distinguishability were experimentally observed,and the novel properties of PT symmetric quantum dynamics were exhibited.Comprehensive studies on parity-time(PT)symmetric systems demonstrated the novel properties and innovative application of non-Hermitian physics in recent years.However,the construction and control of PT symmetric quantum system are still challenging,which restricts the experimental investigation of PT symmetric quantum property and application.We proposed and constructed a recycling-structure PT symmetric quantum simulator for the first time based on the heralded single-photon sources,which can effectively simulate the discrete-time dynamical process of PT symmetric quantum system in both unbroken and broken phases.We investigate the dynamical features of quantum state distinguishability based on the PT symmetric simulator.Our results demonstrate the novel PT symmetric quantum dynamics characterized by the periodical oscillation of state distinguishability in the unbroken phase and the monotonic decay of that in the broken phase.This work also provides a practical experimental platform for the future study of PT symmetric quantum dynamics.3.We demonstrated the temperature dependence of the spin energy-level structure of negatively charged boron vacancy in hexagonal boron nitride by using the photons-assisted method,and its internal reasons were explored.The temperature dependence of the optically detected magnetic resonance(ODMR)spectrum of negatively charged boron vacancy in hexagonal boron nitride in the temperature range of 5 K to 600 K is investigated by using the photons-assisted method.The microwave transition energy is found to decrease monotonically with increasing temperature and can be described by the Varshni empirical equation very well.Considering the proportional relation between energy-level shifts and the reciprocal lattice volume,the thermal expansion might be the dominant cause for energy-level shifts.We also demonstrate that the VB-defects are stable at the temperature up to 600 K.Moreover,we find that there are evident differences among different hBN nanopowders.These results may provide insight into the spin properties of VB-and for the realization of miniaturized,integrated thermal sensors.4.The spin energy-level structure detection and coherent manipulation of the negatively charged boron vacancy in hexagonal boron nitride were realized by using the photons-assisted method,and the effect of nuclear spin bath on the energylevel structure was explored.We detected the energy-level structure of VB-spin defect ensembles in hexagonal boron nitride by using the photons-assisted method,and studied the Rabi oscillation and its related phenomena.We measured the spin-lattice relaxation time T1 and spinspin relaxation time T2,and realized the coherent manipulation of VB-spin defect.In addition,we also explored the effect of nuclear spin bath on the energy-level structure of VB-spin qubits through theoretical simulation of VB-spin dynamics,which laid a foundation for the further application of VB-spin qubits in hexagonal boron nitride on quantum information.The innovations in this thesis are as follows:1.We realized the weak-value amplification under non-unitary evolution by using the spatial light modulator,which proves the advantages of non-unitary evolution over unitary evolution in parameter estimation.2.A PT symmetric quantum simulator with a recycling-structure was constructed for the first time.The novel properties of the quantum dynamics characteristics of state distinguishability were experimentally observed.3.We demonstrated the temperature dependence and coherent spin manipulation of the spin energy-level structure of negatively charged boron vacancy in hexagonal boron nitride by using the photons-assisted method. |
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