Application Cases

Experiment Title: Experimental Techniques for the Generation of High-Performance Light-Atom Entanglement Interfaces

Testing Purpose:Fidelity of entanglement, retrieval efficiency, and storage lifetime are crucial indicators for high-performance photon-atom entanglement interfaces. The primary factors contributing to the decrease in entanglement fidelity are the leakage of write light, read light, and locking light into the detection system. We use a combination of mode cleaners and F-P filters to eliminate these interferences. A ring cavity is employed to enhance the coupling strength between light and atomic ensembles, thereby improving retrieval efficiency. We implement PDH (Pound-Drever-Hall) locking technology to stabilize the cavity length.

Testing Equipment: High Voltage Amplifier, Function Generator, Optical Isolator, Electro-Optic Modulator, Laser, PZT, etc.

Experiment Process:

Figure 1: Schematic Diagram of PDH Locking. Laser: Laser; ISO: Optical Isolator; EOM: Electro-Optic Modulator; Cavity: Mode Cleaner (Ring Cavity); PZT: Piezoelectric Ceramic; BS: Beam Splitter; Detector: Photodetector; HP: High Pass Filter; HV: High Voltage Amplifier; Oscillator: Function Generator; DB: Phase Delay; Mixer: Mixer; LP: Low Pass Filter; PID: Proportional-Integral Controller

A mode cleaner is used to filter out the incoherent components of the light source, and a ring cavity is used to enhance the coupling strength between light and atomic ensembles. Both the mode cleaner and the ring cavity utilize PDH locking technology to stabilize the cavity length, as shown in Figure 1. A frequency-locked laser beam passes through an optical isolator and an electro-optic modulator (driven by a signal from the function generator amplified by the high voltage amplifier) and is then injected into the mode cleaner (ring cavity). The transmitted or reflected cavity signal is detected by a photodetector. The detected signal is mixed with the signal from the function generator after passing through a phase delay and a high pass filter. The mixed signal is filtered by a low pass filter to obtain an error signal. The error signal is processed by a proportional-integral controller and a high voltage amplifier and then fed back to the piezoelectric ceramic of the mode cleaner (ring cavity) to drive the ceramic and stabilize the cavity length.

Experimental Results:

The experimental setup was constructed, and the experimental techniques and methods necessary for realizing high-performance memory were introduced, including precise compensation of the geomagnetic field, mode cleaners, F-P filters, and PDH frequency locking technology. The basic theory of light-atom interaction was also discussed. These techniques and theories lay the foundation for the generation of high-performance atom-photon entanglement interfaces.

High Voltage Amplifier Recommendation: ATA-7015

Figure: Specifications of the ATA-7015 High Voltage Amplifier

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