The Entangling Power of Spacetime

时空的纠缠力量

• 批准号: RGPIN-2020-05205
• 负责人: Mann, Robert
• 金额: $ 4.44万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=740451
• 关键词: Entangling; Power; Spacetime

Quantum physics and gravity, the two foundational pillars of modern physics, remain incompatible despite substantive efforts by the theoretical physics community to unite them. This proposal is about advancing our understanding of their relationship using a novel approach called entanglement harvesting. It brings together the phenomenon of quantum entanglement, perhaps the strangest aspect of quantum physics, with black holes, the most perplexing objects in gravitational physics. Over the past decade it has become clear that spacetime has the capacity to both entangle qubits and to destroy the information they carry. A subtle relationship exists between quantum entanglement, detector responses, quantum fields, and the structure of spacetime. The goal of this proposal is to investigate this relationship by providing both a firm theoretical foundation for its description, and to obtain predictions that can be tested (or at least simulated) by experiment. Qubits can be regarded as idealized detectors that can have high (excited) or low (ground) internal energy. Entanglement harvesting exploits the property that 2 otherwise independent qubits will become entangled upon exposure to the quantum vacuum. The qubits therefore extract (harvest) this vacuum entanglement, the amount depending on their separation, relative motion, and - most importantly - on the structure of space and time in their vicinity. Here gravity is introduced: it curves space and time, so that the entanglement the detectors extract provides information as to how gravity influences quantum entanglement. This proposal focuses on how black holes impact the entanglement that 2 qubits can harvest and preserve. Black holes curve spacetime more than any other objects, trapping anything venturing too close to their edge. Absorbing everything and emitting nothing, they apparently violate the 2nd law of thermodynamics (that disorder, or entropy, always increases). Quantum physics implies black holes radiate (the radiated particles being entangled with inside partners), increasing disorder and restoring the 2nd law. But strangely, as the hole evaporates away, its radiation becomes `entangled with nothing', a situation impossible in normal quantum physics. This is the black hole information paradox: the quantum physics restoring the 2nd law ultimately predicts a contradictory situation. Entanglement harvesting will be used to see how actual quantum objects (the qubits) become entangled when they are near black holes, when black holes form, and when one (or both) falls into a black hole. By quantifying how entanglement depends on qubit separation, energy, and motion in these various settings, we will learn new information about the quantum structure of spacetime. The impact of this research program will be important new knowledge about the entangling properties of black holes, yield new insight into the information paradox, and advance the reconciliation of gravity with quantum physics.

量子物理和引力是现代物理学的两个基本支柱，尽管理论物理界做出了实质性的努力来联合它们，但它们仍然是不相容的。这项提议是关于使用一种名为纠缠收获的新方法来促进我们对他们关系的理解。它将量子纠缠现象与黑洞结合在一起，黑洞是引力物理学中最令人困惑的物体。量子纠缠可能是量子物理学中最奇怪的方面。在过去的十年里，很明显，时空既有纠缠量子比特的能力，也有摧毁它们携带的信息的能力。量子纠缠、探测器响应、量子场和时空结构之间存在着微妙的关系。这项提议的目标是通过为描述这种关系提供坚实的理论基础来研究这种关系，并获得可以通过实验检验(或至少是模拟)的预测。量子比特可以被认为是理想的探测器，它可以具有高(激发)或低(地面)内能。纠缠收获利用了这样一种特性，即两个原本独立的量子比特在暴露在量子真空中时将变得纠缠。因此，量子比特提取(收获)这种真空纠缠，纠缠的数量取决于它们的分离、相对运动，最重要的是，取决于它们附近的时空结构。这里引入了引力：它使空间和时间弯曲，因此探测器提取的纠缠提供了关于重力如何影响量子纠缠的信息。这项提议的重点是黑洞如何影响2个量子比特可以收获和保存的纠缠。黑洞比任何其他物体更能弯曲时空，捕捉任何冒险靠近黑洞边缘的物体。它们吸收一切，不释放任何东西，显然违反了热力学第二定律(无序，或称熵，总是增加)。量子物理意味着黑洞辐射(辐射的粒子与内部伙伴纠缠)，增加无序并恢复第二定律。但奇怪的是，随着黑洞的蒸发，它的辐射变得“一无所有”，这种情况在正常的量子物理学中是不可能的。这就是黑洞信息悖论：恢复第二定律的量子物理学最终预测了一种矛盾的情况。纠缠收获将被用来观察实际的量子物体(量子比特)在接近黑洞时、当黑洞形成时以及当一个(或两个)落入黑洞时是如何变得纠缠的。通过量化纠缠如何在这些不同的环境中依赖于量子比特分离、能量和运动，我们将了解到关于时空量子结构的新信息。这一研究计划的影响将是关于黑洞纠缠性质的重要新知识，对信息悖论有新的见解，并推动引力与量子物理的和解。