This paper proposes a quantum algorithm for Dynamic Metasurface Antennas (DMA) beamforming to suppress interference for an amplify-and-forward relay system in multi-base station environments. This algorithm introduces an efficient dynamic block initialization and overarching block update strategy, which can enhance the Signal-to-Interference-plus-Noise Ratio (SINR) of the target base station (BS) signal without any channel information. Furthermore, we built a relay system with DMA as the receiving antenna and conducted outdoor 5G BS interference suppression tests. To the best of our knowledge, this is the first paper to experiment DMA in commercial 5G networks. The field trial results indicate an SINR improvement of over 10 dB for the signal of the desired BS.