Homodyne detection for pulse-by-pulse squeezing measurements

TL;DR

This work tackles the challenge of high-speed pulsed homodyne detection for continuous-variable quantum states, addressing electronic bandwidth and noise limitations that hinder pulsed quantum information processing. The authors design and implement three wideband homodyne detectors at near-infrared and telecom wavelengths using OPA856-based TIAs to achieve repetition-rate operation up to 150 MHz, while preserving shot-noise clearance and mode-matching. They demonstrate pulse-by-pulse squeezing measurements across multiple spectral modes, validating the detectors' ability to resolve ultrafast quantum features without sacrificing spectral multimode structure. The detectors offer high common-mode rejection, substantial shot-noise clearance, and room-temperature operation, enabling practical, high-rate CV quantum information protocols and spectral-mmultiplexed squeezing measurements.

Abstract

Homodyne detection is a phase-sensitive measurement technique, essential for the characterization of continuous-variable (CV)-encoded quantum states of light. It is a key component to the implementation of CV quantum-information protocols and benefits from operating, by design, at room temperature. However, performing high-speed quantum information processing remains a major challenge, as conventional homodyne detectors often fail to sustain pulsed operation at high repetition rates due to electronic limitations. We present wideband homodyne detectors operating at near-infrared (NIR) and telecom wavelengths, with optimized performance at repetition rates up to 150 MHz. We demonstrate their performance by resolving the pulse-by-pulse structure of squeezed states of light at telecom wavelengths while preserving their spectral multimode properties.

Figures (10)

• Figure 1: Schematics of a homodyne setup. BS: beam splitter; Piezo: piezo-electric actuator.
• Figure 2: Simplified schematics of a homodyne detector. $i_{12}$: subtracted photocurrent; $R_F$ and $C_F$ or the feedback resistance and capacitance respectively; $V_{out}$ is the voltage at the output of the TIA.
• Figure 3: Schematics of the photodedection and current subtraction. s3883: Hamamatsu Si photodiodes for the detection of NIR light.
• Figure 4: Simplified schematic of a transimpedance amplifier (TIA).
• Figure 5: OPA 856 lower-bandwidth. (a) SNC of the NIR homodyne detector as a function of frequency. (b) Experimental measurement of the CMRR.