Optimal Efficiency For The Orbital Angular Momentum Photon Quantum Interface Via Single Photon Frequency Upconversion

As the application of orbital angular momentum(OAM)of light develops in quantum communication,the OAM photon quantum interface for the transmission wavelength from the telecom communication to quantum information storage in visible regime is required.Here we demonstrate the optimal efficiency for the OAM photons quantum interface based on the frequency upconversion from telecom wavelength to visible regime by sum-frequency generation.The infrared photons at 1558.0 nm carrying different OAM values could be converted to the visible regime of 622.2 nm with the optimal efficiency via adjusting the pump beam waist radius and the pump beam intensity.In recent years,the light with orbital angular momentum has received enough attention in many natural science field.Its special vortex phase structure results the intensity of the light beam at the center is zero,and around the center the phase is rotated,and the phase in the center is undefined.However,its topological charge number lmultiplied by h decides the orbital angular momentum value of one photon.The OAM is quantized to equivalent to be lh,which is larger than spin angular momentum.The space of orbital angular momentum has infinity dimension if we use OAM to express one photon.As a result,its capacity of carrying information improves vastly and make a great contribution in quantum communication and computation.And its special construction of vortex phase gives us a new technique to manipulate micro particles,such as cells,in biography,and medical research.On account of the hollow core structure the reflective power from the cell wall would be decreased,we can move,rotate,and capture cells via the OAM light beam.In this paper,we combine the OAM light beam and frequency upconversion technique to simulate the process of Laguerre-Gaussian shape light being converted in the nonlinear material.The frequency upconversion is an infrared light detection technique based on nonlinear sum frequency generation process,in which the energy and momentum of the photons are conserved.When combine with the OAM pulse light,we can find the orbital angular momentum is conserved,the third conservation equation formula.In fact,we simulate three cases,each case has different OAM value and get the different conversion process and set the pump beam size and pump beam intensity to get the optimal quantum conversion efficiency in combination with the experiment result.Fortunately,we discovery the suitable ratio value of the beam size and the pump intensity to realize the maximum conversion of the signal light,and can be used to construct the quantum information interface,spectral analysis application and new imaging system.In this paper,we vary the orbital angular momentum value of the signal light and pump light from 0 to h,and get different conversion efficiency,for example,when the orbial angular momentum of signal light and pump light are both h,the conversion efficiency can be up to 93.6%.