Locking The Phase Of Balanced Homodyne Detection System For Squeezed Light

Quantum optic is an advanced research topic in modern science in the world. As the existence of light particles, so even completely coherent light field exist noise. This kind of noise is determined by the light emission process itself, is called shot noise limit(SNL).It is a manifestation of the particle of light.Although the noise is very low, but as the highly development of modern science and technology, we need more precise measurements in many sectors. So we need to reduce the noise of the light. Therefore, reducing the noise of the light has already become an important research subject. A good way to breakthrough shot noise limit is to produce squeezed light. According to Heisenberg’s uncertainty principle, if light’s one component’s noise is lower than the shot noise limit, its conjugate component’s noise will be greater than shot noise limit. This kind of light is called squeezed light. Squeezed light can be widely used in many research fields of quantum optics, such as quantum computer, quantum information ultra-weak transmission, quantum communication and so on. Especially in the case of quantum communication, two single-mode squeezed light interference through a beam splitter output can be a good source of quantum entanglement. And quantum entanglement source, which is the core of the quantum information, can be used in quantum secret communication, quantum teleportation, quantum dense coding, and others that classic light can not do.In this paper, we mainly to introduce the production of vacuum squeezed light and lock the phase of balanced homodyne detection system for squeezed light.The main content has the following three parts:Firstly, simply review the emergence and development of quantum mechanics and quantum optics, introduces the classification and definition of squeezed light.Secondly, nonlinear process and phase matching technology is introduced, using PPKTP crystal as the core to build optical parametric oscillation cavity, a single-mode polarization-preserving fiber was carried out as the mode clean of1064nm light, the532nm green light was injected into the cavity. We measured2dB vacuum squeezing and5dB amplification.Thirdly, we put a phase modulator on the path of signal light, then the signal light that was injected into the phase sensitive optical parameter amplifier is phase modulated. The output squeezed light of OPA is detected by the balanced homodyne detection system. We can demodulate the phase modulation signal to achieve the error signal, which is used to lock the relative phase of zero between the local and the quantum light fields (corresponding to the quadrature-amplitude of the unknown light field). We obtained2dB squeezing and4dB amplification. And we can judge which the quadrature components we measured is by observing the modulation...