不用测量就能保存量子态,实现可重复使用的量子记忆。
Guess, SWAP, Repeat : Capturing Quantum Snapshots in Classical Memory
- 用机器学习+交换测试估算量子态,非破坏性捕获状态快照。
- 实测在IBM硬件上对已知态重建保真度接近1.0,模拟平均保真度0.999。
- 适合量子调试、长期存储,为未来量子内存架构奠基。
我们提出一种新方法,可在不直接测量的情况下观测量子态,从而保留其以供重复使用。该方法允许在单个量子电路中任意位置逐次观察多个量子态,并将其保存至经典内存而不被破坏。这些保存的态可按需由下游应用调用,引入动态可编程的量子内存概念,支持模块化、非破坏性的量子工作流。我们设计了一个与硬件无关的、基于机器学习的框架,通过仅利用保真度作为学习信号,实现对量子态的非破坏性估计(即“快照”),并支持经典存储与后期重构,类似经典计算中的内存操作。这一能力对量子系统的调试、内省和持久记忆至关重要,但受制于无克隆定理与测量破坏性。我们的猜-检策略采用交换测试进行保真度估计,指导状态重构。实验探索了基于梯度的深度神经网络与无梯度进化策略,均仅依赖保真度信号。我们在IBM量子硬件上验证了框架关键组件,对哈达玛态等已知态实现了约1.0的高保真度重建;在仿真中,对100个随机量子态的平均保真度达0.999。这为非挥发性量子内存提供了路径,支持量子信息的长期存储与复用,为未来量子内存架构奠定基础。
原文摘要 · Abstract (English)
We introduce a novel technique that enables observation of quantum states without direct measurement, preserving them for reuse. Our method allows multiple quantum states to be observed at different points within a single circuit, one at a time, and saved into classical memory without destruction. These saved states can be accessed on demand by downstream applications, introducing a dynamic and programmable notion of quantum memory that supports modular, non-destructive quantum workflows. We propose a hardware-agnostic, machine learning-driven framework to capture non-destructive estimates, or "snapshots," of quantum states at arbitrary points within a circuit, enabling classical storage and later reconstruction, similar to memory operations in classical computing. This capability is essential for debugging, introspection, and persistent memory in quantum systems, yet remains difficult due to the no-cloning theorem and destructive measurements. Our guess-and-check approach uses fidelity estimation via the SWAP test to guide state reconstruction. We explore both gradient-based deep neural networks and gradient-free evolutionary strategies to estimate quantum states using only fidelity as the learning signal. We demonstrate a key component of our framework on IBM quantum hardware, achieving high-fidelity (approximately 1.0) reconstructions for Hadamard and other known states. In simulation, our models achieve an average fidelity of 0.999 across 100 random quantum states. This provides a pathway toward non-volatile quantum memory, enabling long-term storage and reuse of quantum information, and laying groundwork for future quantum memory architectures.
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