| With the rapid development of science today,the development of quantum mechanics technology has become an important foundation of world civilization.An important concept in quantum mechanics is quantum entanglement.What can not be done in classical physics can be achieved through the application of quantum entanglement.In recent years,people have used quantum entanglement to complete many important experiments in the field of quantum information,such as quantum key distribution,quantum teleportation,quantum computing,quantum simulation,etc.With the rapid development of quantum information technology,people are also vigorously developing and improving the core of quantum information technology,that is,the quantum entanglement light source.Practical applications require the design of better entangled beam generators and efficient measurement of entangled beams.The parametric down-conversion process in the nonlinear effect is used to prepare the quantum entangled beam,with a focus on second-order nonlinear effects in nonlinear effects.Commonly used nonlinear crystal materials are the KDP(potassium dihydrogen phosphate),BBO(barium metaborate),PPLN(periodically polarized lithium niobate),PPKTP(periodically polarized potassium titanyl phosphate)and so on.The nonlinear crystal material used in this thesis is KTP(potassium titanyl phosphate).Entangled beams can be generated by NOPA(Non-Degenerate Optical Parametric Amplifier)below the threshold,but the power of the entangled beams produced is low,and low-power entangled beams are not conducive to long-distance transmission.People can also generate quantum entangled beams by constructing a non-degenerate optical parametric oscillator(NOPO)that operates above the threshold.The entangled beam generated by the NOPO cavity can reach several milliwatts,tens of milliwatts,or even higher power.In this paper,a NOPO cavity with a higher degree of precision for pumping light above the threshold is designed,which can generate entangled beams at low pump power.In addition,a pair of unbalanced Mach-Zehnder interferometers with short optical path difference are constructed,and a high-frequency quantum noise detector is designed to make the generation and measurement of continuous variable entangled beams simpler and more efficient.The main contents are as follows:(1)The classical and quantum characteristics of the entangled light field output from the high-finesse cavity operating above the threshold are analyzed,and the NOPO cavity with low pump power is designed.(2)A high-frequency narrow-band quantum noise detector is designed.In this paper,a high-frequency narrow-band quantum noise detector is designed.In order to solve the problem of insufficient gain of the quantum noise detector at high frequencies,a narrowband amplification design is adopted to design a high-frequency narrow-band quantum noise detector at a center frequency of 83.1 MHz.(3)The measurement method of the entangled light field generated by NOPO above the threshold is introduced,an unbalanced Mach-Zehnder interferometer with an analysis frequency of 83.1 MHz is built,and the intensity difference noise spectrum and phase and noise spectrum of NOPO are measured at the analysis frequency.In the work done in this article,the innovations embodied are as follows:(1)Design a NOPO cavity with high green light precision that operates above the threshold to generate entangled beams at lower pump power.(2)A high-frequency narrow-band quantum noise detector was designed,which overcomes the problem of the previous broadband balanced zero-beat detector,which is affected by the gain-bandwidth product at high frequency,resulting in low gain or even detection.The analysis frequency is 83.1 MHz A good gain is achieved everywhere.(3)Constructed an unbalanced Mach-Zehnder interferometer that analyzes the frequency at high frequencies,and analyzed and measured the noise characteristics of the entangled light field generated by the NOPO cavity operating above the threshold at high frequencies. |
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