Many elusive quantum phenomena emerge from a quantum system interacting with its classical environment. Quantum simulators enable us to program this interaction by using measurement operations. Measurements generally remove part of the entanglement built between the qubits in a simulator. While in simple cases entanglement may disappear at a constant rate as we measure qubits one by one, the evolution of entanglement under measurements for a given class of quantum states is generally unknown. We show that consecutive measurements of qubits in a simulator can lead to criticality, separating two phases of entanglement. Using up to 48 qubits, we prepare an entangled superposition of ground states to a classical spin model. Progressively measuring the qubits drives the simulator through an observable vitrification point and into a spin glass phase of entanglement. Our findings suggest coupling to a classical environment may drive critical phenomena in more general quantum states.

许多难以捉摸的量子现象来自于与其经典环境相互作用的量子系统。量子模拟器使我们能够通过使用测量操作来对这种交互进行编程。测量通常会消除模拟器中量子位之间建立的部分纠缠。虽然在简单的情况下，当我们一个一个地测量量子比特时，纠缠可能会以恒定的速率消失，但在给定类别的量子态的测量下纠缠的演变通常是未知的。我们表明，在模拟器中连续测量量子位会导致临界状态，从而分离纠缠的两个阶段。使用多达 48 个量子位，我们准备了基态纠缠叠加到经典自旋模型。逐步测量量子位驱动模拟器通过可观察的玻璃化点并进入纠缠的自旋玻璃相。我们的研究结果表明，与经典环境的耦合可能会在更一般的量子态中驱动临界现象。