Nonclassicality of the Harmonic-Oscillator Coherent State Persisting up to the Macroscopic Domain (NoHarmMacro)

谐波振荡器相干态的非经典性持续到宏观域 (NoHarmMacro)

• 批准号: EP/X009491/1
• 负责人: Hendrik Ulbricht
• 金额: $ 86.65万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FX009491%2F1
• 关键词: Nonclassicality; Harmonic; Oscillator; Coherent; State

Can the most "classical-like" of all quantum states, namely the Schrödinger coherent state of a harmonic oscillator, exhibit nonclassical behavior? We find that for an oscillating object initially in a coherent state, merely by observing at various instants which spatial region the object is in, the Leggett-Garg inequality (LGI) can be violated through a genuine negative result measurement, thereby repudiating the everyday notion of macrorealism. This violation thus reveals an unnoticed nonclassicality of the very state which epitomizes classicality within the quantum description. It is found that for any given mass and oscillator frequency, a significant quantum violation of LGI can be obtained by suitably choosing the initial peak momentum of the coherent state wave packet. It thus opens up potentially the simplest way (without coupling with any ancillary quantum system or using nonlinearity) for testing whether various recently engineered and sought after macroscopic oscillators, such as feedback cooled thermal trapped nanoparticles, are indeed bona fide nonclassical objects.The overarching goal of this project is to perform a levitated optomechanical experiment that, by sampling the Leggett-Garg inequality (LGI) for a coherent motional state of a nanoparticle, directly probing quantum non-locality in the context of predictions made by macroscopic realism. In order to reach this goal, we will develop an experimental platform that will allow the following achievements: 1) To rapidly repeat single-particle experimental dynamical trajectories to gain sufficient counting statistics in order to reconstruct the unique features of the delocalized quantum state; 2) To trap and manipulate (cool) sufficiently large particles (around 100 nm in diameter), to enable sufficient time for the wavefunction evolution, and to realise position measurements at sufficient high resolution. The NoHarmMacro experiment will open the door to a new macroscopic domain for testing quantum mechanics in the low energy non-relativistic regime -- the very regime where gravity is expected to affect the dynamics of quantum systems.NoHarmMacro leverages substantial expertise in experimental levitated optomechanical techniques (PI Ulbricht at Southampton) with pioneering analytical expertise (Co-I Bose at UCL) to maximise the success of both objectives.

所有量子状态中最“古典”的状态，即谐波振荡器的Schrödinger相干状态，暴露了非古老行为？我们发现，对于最初处于连贯状态的振荡对象，仅通过观察该物体所在的空间区域的各个瞬间，可以通过真正的负面结果测量来违反leggett-garg不平等（LGI），从而否认每天的大核主义通知。揭示了状态的未经宣传的非经典性，它表现了量子描述中的经典性。发现对于任何给定的质量和振荡器频率，可以通过适当选择相干状态波包的初始峰动量来获得对LGI的重大量子违规。因此，它可以打开最简单的方法（不与任何辅助量子系统耦合或使用非线性）来测试各种最近设计和寻求的宏观振荡器，例如反馈冷却的热捕获纳米颗粒，确实是真正的非经典物体。该项目的总体目标是执行悬浮的光力学实验，通过对纳米颗粒的相干运动状态进行leggett-garg不平等（LGI），直接探测量子非元素在宏观现实主义所做的预测的上下文中。为了实现这一目标，我们将开发一个实验平台，该平台将允许以下成就：1）快速重复单粒子实验动力学轨迹，以获得足够的计数统计量，以重建DELAICALIZED量子状态的独特特征； 2）捕获并操纵（冷却）足够大的颗粒（直径约100 nm），以使足够的时间进行波函数演化，并以足够的高分辨率实现位置测量值。 Noharmmacro实验将为一个新的宏观领域打开大门，用于测试低能量非偏见性方案中的量子力学 - 预计重力会影响量子系统动力学的一个机制。Noharmmacro利用实验性的Opemanial Botiroice Botirose（PIISE BOISE）（PIISE BOISE pi ulbrich at at South Atmpton）的实质性专业知识（ UCL）最大化这两个目标的成功。