Yu Zhang

In the current Noisy Intermediate-Scale Quantum (NISQ) era, noise is widely viewed as a primary obstacle to fault-tolerant quantum computation. In this work, we flip this perspective by demonstrating that noise can be harnessed constructively in key quantum algorithms. First, drawing on the Eigenstate Thermalization Hypothesis, we show that using both classical and quantum simulations that noise generically accelerates Gibbs state preparation. In our model, we find that phase-flip noise, and more generally Haar-random noise, drives localized thermalization that yields speedups of up to a factor of ∼3.5× as compared to noiseless systems. We also show that this induces thermalization in systems that would otherwise fail to do so. Building on this, we further show that intrinsic noise can be selectively leveraged to emulate nonunitary dynamics, enabling efficient simulation of open quantum systems without encoding dissipation into unitary circuits. By preserving physical noise rather than correcting it entirely, we show that this approach reduces qubit and gate overhead and relaxes fidelity requirements on quantum hardware. Taken together, these results establish a paradigm in which noise is harnessed as a computational resource, enabling practical quantum advantages on near-term and future quantum devices.

Communication and sensing technologies play crucial roles in various aspects of modern society. The seamless combination of communication and sensing systems has attracted significant interest in recent years. Without adding core devices, vibration-sensing functions can be integrated to build a quantum network with high efficiency and versatility. In this study, we propose and demonstrate a network architecture that integrates a downstream quantum access network (DQAN) and vibration sensing in optical fibers. By encoding the key information of eight users simultaneously on the sidemode quantum states of a single laser source and successively separating them using a specially designed narrow-bandwidth filter network, we achieved a secure and efficient DQAN with an average key rate of 19.4 kbps over an 80 km single-mode fiber. Meanwhile, vibration locations with spatial resolutions of 131, 25, and 4 m at vibration frequencies of 100 Hz, 1 kHz, and 10 kHz, respectively, were implemented using the existing DQAN system infrastructure. The results indicate that the backward probe beam has a negligible effect on the DQAN system. Our integrated architecture provides a viable and cost-effective solution for building a quantum communication sensor network and paves the way for the functionality expansion of quantum communication networks.

Quantum key distribution (QKD) is the fastest-growing and relatively mature technology in the field of quantum information, enabling information-theoretically secure key distribution between two remote users. Although QKD based on off-the-shelf telecom components has been validated in both laboratory and field tests, its high cost and large volume remain major obstacles to large-scale deployment. Photonic integration, featured by its compact size and low cost, offers an effective approach to addressing the above challenges faced by QKD. Here, we implement a high-performance, integrated local local oscillator continuous-variable (CV) QKD system based on an integrated silicon photonic transmitter and receiver. By employing a high-speed silicon photonic integrated in-phase and quadrature modulator, a high signal-to-noise ratio and high bandwidth silicon photonic integrated heterodyne detector, and digital signal processing, our CV-QKD system achieves a symbol rate of up to 1.5625 GBaud. Furthermore, the system achieves high secret key rates of 14.7 and 2.46 Mbps over 25.8 and 50.4 km standard single-mode fiber, respectively, using an 8-phase-shift keying discrete modulation. Our fully integrated CV-QKD system with high symbol rate and long transmission distance pays the way for the quantum secure communication network at metropolitan area.