基于单个光电二极管的腔辅助零差检测
Cavity-assisted homodyne detection with a single photodiode
AI总结：
本文提出腔辅助零差检测方法，可在适中本地振荡器功率下实现近1的信号传输效率，抑制技术本地振荡器边带，解决了高带宽下平衡零差检测的匹配难题。
AI中文摘要：
高频压缩态对量子计量和信息处理至关重要，但吉赫兹频率下的正交测量仍具挑战性。标准方法平衡零差检测（BHD）需要两个光电探测通道具备紧密匹配的复传输函数，以抑制本地振荡器（LO）噪声并维持定义明确的读出正交分量，这种匹配在高带宽下愈发困难。强不对称的单光电二极管零差检测可避免该要求，但要实现高信号效率和散粒噪声余量，通常需要数百毫瓦的LO功率，且无法抑制技术LO边带。本文提出腔辅助零差检测：量子场和LO分别进入阻抗匹配行波腔的两个端口，谐振的LO载波传输至光电探测器，与从腔反射的非谐振信号边带拍频，同时抑制腔线宽外的技术LO边带。本文推导了包含腔内损耗的量子输入输出关系和线性化光电流，表明在适中入射LO功率下可实现近1的信号传输效率，腔线宽和自由光谱范围决定可用检测带宽。
英文摘要：
High-frequency squeezed states are important for quantum metrology and information processing, but quadrature measurements at gigahertz frequencies remain challenging. Balanced homodyne detection (BHD), the standard approach, requires closely matched complex transfer functions in both photodetection channels to suppress local-oscillator (LO) noise and maintain a well-defined readout quadrature. This matching becomes increasingly difficult at high bandwidths. Strongly asymmetric single-photodiode homodyne detection avoids this requirement, but achieving high signal efficiency and shot-noise clearance typically requires hundreds of milliwatts of LO power and does not suppress technical LO sidebands. I propose cavity-assisted homodyne detection, in which the quantum field and LO enter separate ports of an impedance-matched traveling-wave cavity. The resonant LO carrier is transmitted to the photodetector, where it beats with off-resonant signal sidebands reflected from the cavity. At the same time, technical LO sidebands outside the cavity linewidth are suppressed. I derive the quantum input-output relations and linearized photocurrent including intracavity loss, and show that near-unity signal-transfer efficiency can be achieved at moderate incident LO power. The cavity linewidth and free spectral range determine the usable detection band.
