High-efficiency Weak-trace-free Counterfactual Communication via Quantum Zeno Effect

Abstract

The quantum Zeno effect, which inhibits quantum state evolution via repeated weak measurements, significantly enhances the efficiency of interaction-free measurement (IFM). This fundamental mechanism facilitates high-efficiency counterfactual quantum communication, enabling information delivery without particle transmission through the channel. However, the transmission time of the counterfactual communication requires minutes for bit and suffers the bit error when transmitting an image. Applying the quantum Zeno effect, we experimentally demonstrate high-efficiency weak-trace-free counterfactual communication on a quantum photonic chip, achieving a transmission probability of 74.2 $\pm$ 1.6\% for bit 0 and 85.1 $\pm$ 1.3\% for bit 1. Furthermore, we successfully transmit our group's logo -- Quanta -- through counterfactual communication, and reduce the time cost from minutes to seconds for bit, with zero bit errors after information processing. Our study provides a promising approach for secure and efficient communication using integrated silicon quantum photonics.

Figures (3)

• Figure 1: The schematic and structure of the upgraded counterfactual communication protocol. (a) During the classical communication process, Eve can obtain the information from Alice to Bob by intercepting the information-carried particles. However, since Alice and Bob do not transmit any particles during the counterfactual communication, Eve can not acquire any information. (b) The updated protocol for the counterfactual communication. (c) The success probabilities of transmitting bit 0 and bit 1 are simulated with various $M$ and $N$. Balancing the trade-off between feasibility of implementation and success probabilities of transmission, we choose $M = 3$ and $N = 6$ in our experimental scheme.
• Figure 2: The experimental setup and transmission result. (a) The chip contains photon-pairs source and the counterfactual transmission structure. The structures of outer and inner cycle in chip are shown as above, and the two red components in the outer cycle represent the reconfigurable BS-N and the SW in the inner cycle. (b) Success probabilities for bit 0 and bit 1 are 74.2 ± 1.6% and 85.1 ± 1.3%, compared to theoretical limits. (c) The transmission of our group logo, Quanta, in $50 \times 50$ pixels. We transmitted the logo in different transmission time cost for 1 bit, with $T$ =1s for 1 bit in (c-2) and $T$ =5s for 1 bit in (c-3).
• Figure 3: The whole experiment platform. Before entering the chip, pump light is produced by the laser and is adjusted with several steps, including spectral filtering by WDM and polarization modification by PC. The parameters of the on-chip interferometer are adjusted by the signal DAC with Alice and Bob. Finally, the output photons are adjusted again and are detected by the SNSPD and counted with the TDC.