Experimental implementation of a quantum pulse gate for multi-mode quantum networks

We implemented a single-mode Quantum Pulse Gate (QPG), which singles out specific ultrafast time-frequency (TF) modes from multi-mode quantum pulses by transferring them to another wavelength. We directly measured the TF mode structure of our QPG and demonstrate a high degree of control over these modes. In addition, we prove the single-mode operation by monitoring a sharp drop in the conversion efficiencies for orthogonal TF mode combinations. Our QPG constitutes an important building block for future multi-mode quantum communication and information applications.