Low-noise, transformer-coupled resonant photodetector for squeezed state generation

Abstract

In an actual setup of squeezed state generation, the stability of a squeezing factor is mainly limited by the performance of the servo-control system, which is mainly influenced by the shot noise and gain of a photodetector. We present a unique transformer-coupled LC resonant amplifier as a photodetector circuit to reduce the electronic noise and increase the gain of the photodetector. As a result, we obtain a low-noise, high gain photodetector with the gain of more than 1.8×10 V/A, and the input current noise of less than 4.7 pA/Hz. By adjusting the parameters of the transformer, the quality factor Q of the resonant circuit is close to 100 in the frequency range of more than 100 MHz, which meets the requirement for weak power detection in the application of squeezed state generation.

Realization of ultralow power phase locking by optimizing Q factor of resonant photodetector*

“…The results indicate that the new-designed RPD can effectively improve the performance of quantum optics experiments. [28,29] Utilizing the sub-nW locking technique, we have experimentally completed the demonstration of channel multiplexing quantum communication. [33]…”

“…[28] Subsequently, by adding a winding transformer between the photodiode and the load resistance, the Q factor of the RPD was close to 100 in the frequency region of higher than 100 MHz. [29] Except for the extension of the resonant frequency, the improvement of the Q factor is another eternal pursuit of the RPD.…”

500MHz resonant photodetector for high-quantum-effciency, low-noise homodyne measurement

“…The terminal capacitance also deteriorates the SNR in high-frequency region 14 , making it difficult to simultaneously achieve high SNR and wide bandwidth. An alternative approach is the resonant architecture [15][16][17][18] , where a high transimpedance gain and good SNR is achieved at the resonant frequency. Resonant detectors are often used for high-sensitivity purposes, for example gravitational wave detectors 16 .…”

A low-noise resonant input transimpedance amplified photodetector

“…Initial prototype designs that had the resonant input connected directly to the non-inverting a) william.bowden@npl.co.uk op-amp stage were unable to achieve an input-referred current noise below 3 pA/ √ Hz at 50 MHz or higher 8 . One option would be to use a transformer 9 to couple the diode to the amplifier in order to boost the photocurrent, but this has the drawback of also amplifying the diode capacitance 10 . With the JFET input, the current noise depends on the drain leakage current set by the effective resistance R eq of the gate.…”