Generation Of Continuous Variable High-dimensional Multimode Entanglement

Quantum entanglement states are essential for solving questions in quantum measurement,quantum communication,quantum computing and are at the heart of quantum information science.With the development of quantum technologies,it enables the applications in high-capacity quantum information tasks,such as large-capacity quantum communication,distributed and multi-parameter,fault-tolerant quantum computing.For the purpose,it is of key importance to generate multimode and large-scale continuous variable(CV)quantum states.To date,preparing multimode entanglement with individual degrees of freedom(Do Fs),such as spatial mode,frequency or wavelength,and time bin,has gradually matured.With the boost of multimode entanglement,multiplex CV quantum communication has been realized and demonstrates the prospect of reinforcing the channel capacity.To further extend the scale and dimension of entanglements,it is necessary to develop techniques for simultaneous control of multiple degrees of freedom.Similar to the demonstrations in the field of discrete variables,such as compact quantum information processing protocols based on single-photon time and frequency degree-of-freedom coding,quantum teleportation of the composite quantum states of a single photon encoded in both spin angular momentum(SAM)and orbit angular momentum(OAM),quantum key distribution based on spatiotemporal degrees of freedom and rotation invariant modes,and the reversible quantum logic operations between the photons’ three degrees of freedom of path,polarization,and orbital angular momentum,continuous variable high-dimensional multimode entanglements are expected to play an advantage in these applications.This thesis focuses on the relevant theoretical and experimental work of CV highdimensional multimode entangled light field.The main research content are as follows:1.Based on the two spatial shaping schemes,an arbitrary high-order laser mode was experimentally generated and evaluated in quality.By single spatial light modulator(SLM)spatial filtering technology,high-purity high-order laser modes were prepared,which may be directly used as the pump field for multi-mode optical parametric oscillator(OPO)in the related research,such as spatial multi-mode entanglement in the OPO process.By cascading two SLM,high-order modes were produced in a low-loss manner,which were used for the study of squeezed light fields in different spatial modes.Meanwhile,the corresponding control program had been independently developed for the phase hologram calculation and experimental control.2.By compensating both the astigmatism and the dispersion,we had directly generated high-dimensional multimode entanglement states with frequency comb entanglement,OAM,and SAM entanglement simultaneously.For each pair of entanglement modes,the degree of entanglement is about-3.3 d B.In addition,the optimal entanglement measurement scheme under detuning conditions was proposed.3.Based on the high-order Poincaré sphere,we discussed the spin-orbital mode entanglement.We also provide the spin-orbital mode entanglement criterion according to Duan and Simon’s entanglement criterion.By implementing a unitary transformation on one beam of the entangled pair,arbitrary spin-orbit modes entanglement on the high-order Poincaré sphere can be realized.Under the Stokes basis of the high-order Poincaré sphere,the spin-orbit total angular momentum entanglement was characterized.4.The multiplexed quantum dense coding(QDC)was experimentally studied.We implemented the traditional QDC,the spatial mode multiplexing QDC and space-frequency multiplexing QDC.When the average photon number in the channel is greater than 1.46,the channel capacity of the space-frequency multiplexing QDC scheme exceeds the optimum channel capacity for single-mode dense coding.5.The signal transmission characteristics of noiseless amplifier assisted phasesensitive amplifier was analyzed.By comparing different noise channels on the signal transmission performance for quantum state,we evaluated the performances of the amplifier in quantum information sensing applications,and conducted the experiment based on the coherent state.The innovative work among this thesis are as follows:1.We optimized the holographic algorithm and improved the preparation efficiency of the high-purity laser mode.The energy efficiency for 10 th order Hermite-Gaussian modes and Laguerre-Gaussian modes were surpassed over 32.5% and 43% respectively.We have also developed an application control program for producing an arbitrary complex light field based on spatial light modulators.2.We reported an approach based on a single type-II OPO cavity that was optimized for multi-frequency,multi-polarization and multi-spatial modes using dispersion,astigmatism compensation and locking control.We have directly generated highdimensional CV entanglement states with frequency comb entanglement,OAM,and SAM entanglement simultaneously.3.We had experimentally demonstrated space-frequency multiplexing quantum dense coding for the first time.The channel capacity has been significantly enhanced.4.We characterized of the high-order Poincaré sphere Stokes parameters.Besides,we proposed and verified the spin-orbit total angular momentum entanglement.