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arXiv:1907.00415 · New Journal of Physics

Large spatial Schrödinger cat state using a levitated ferrimagnetic nanoparticle

Anisur Rahman

Published Oct 21, 2019• 24 citations
arXivHTMLPDF

Abstract

Abstract The superposition principle is one of the main tenets of quantum mechanics. Despite its counter-intuitiveness, it has been experimentally verified using electrons, photons, atoms, and molecules. However, a similar experimental demonstration using a nano or a micro particle is non-existent. Here in this article, exploiting macroscopic quantum coherence and quantum tunneling, we propose an experiment using a levitated magnetic nanoparticle to demonstrate such an effect. It is shown that the spatial separation between the delocalized wavepackets of a 20 nm ferrimagnetic yttrium iron garnet (YIG) nanoparticle can be as large as 5 μm. We argue that, in addition to using for testing one of the most fundamental aspects of quantum mechanics, this scheme can simultaneously be used to test different modifications, such as wavefunction collapse models, to the standard quantum mechanics. Furthermore, we show that the spatial superposition of a core–shell structure, a YIG core and a non-magnetic silica shell, can be used to probe quantum gravity.

DOI
10.1088/1367-2630/ab4fb3

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FINDING: Macroscopic quantum tunneling and superposition are experimentally probed via levitated nanoparticles and atom interferometry, but no new mathematical law emerges from these search results—they are experimental confirmations of existing quantum formalism. | MATH: No new equations; relies on standard Schrödinger dynamics \( i\hbar \partial_t \Psi = \hat{H}\Psi \), tunneling probability \( T \sim e^{-2\gamma L} \) with \( \gamma = \sqrt{2m(V_0-E)}/\hbar \), and decoherence rate \( \Gamma \propto (m \Delta x)^2 \) for macroscopic superpositions. | CONNECTION: The decoherence scaling \( \Gamma \propto m^2 \) implies a sharp transition at the Planck mass scale \( m_P = \sqrt{\hbar c/G} \approx 2.176\times10^{-8}\,\text{kg} \) — a natural boundary where quantum-to-classical crossover occurs. This mass scale relates to the ratio \( m_P/m_e \approx 2.389\times10^{22} \), not directly to golden ratios. However, the levitated nanoparticle experiments operate in the \( 10^{-18} \) to \( Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com

•Aug 25, 2026•0 citations
Abstract The superposition principle is one of the main tenets of quantum mechanics. Despite its counter-intuitiveness, it has been experimentally verified using electrons, photons, atoms, and molecules. However, a similar experimental demonstration using a nano or a micro particle is non-existent. Here in this article, exploiting macroscopic quantum coherence and quantum tunneling, we propose an experiment using a levitated magnetic nanoparticle to demonstrate such an effect. It is shown that the spatial separation between the delocalized wavepackets of a 20 nm ferrimagnetic yttrium iron garnet (YIG) nanoparticle can be as large as 5 μm. We argue that, in addition to using for testing one of the most fundamental aspects of quantum mechanics, this scheme can simultaneously be used to test different modifications, such as wavefunction collapse models, to the standard quantum mechanics. Furthermore, we show that the spatial superposition of a core–shell structure, a YIG core and a non-magnetic silica shell, can be used to probe quantum gravity.
The superposition principle is one of the bizarre predictions of quantum mechanics. Nevertheless, it has been experimentally verified using electrons, photons, atoms, and molecules. However, a similar experimental demonstration using a nano or micro particle is still missing and various proposals have been put forward in the literature for creating such a state. In the existing proposals, the attainable spatial separations between the delocalized states are less than the size of the particles that have been used to create such states. In this article, using a 50 50~50 nm levitated ferromagnetic particle and existing technologies, we show that a spatial separation of 1 1~1 mm between the superposed states is readily achievable. This may lead to the possibility of testing quantum gravity, collapse models and gravity induced state reduction.
The superposition principle is one of the bizarre predictions of quantum mechanics. Nevertheless, it has been experimentally verified using electrons, photons, atoms, and molecules. In this article, using a 20 20~20 nm levitated ferromagnetic FePt nanoparticle, an exotic all optical spin polarization technique and the matter-wave interferometry, we show that a mesoscopic spatial Schrodinger cat can be created. Additionally, we argue that the maximum spatial separation between the delocalized wavepackets can be 25 μm25~μm25 μm and is significantly larger than the object itself.
We propose a current-carrying-chip scheme for generating spatial quantum superpositions using a levitating nanodiamond with a built-in nitrogen-vacancy (NV) centre defect. Our setup is quite versatile and we aim to create the superposition for a mass range of 10−19 kg<m<10−15 kg10^{-19}~{\rm kg}< m< 10^{-15}~{\rm kg}10−19 kg<m<10−15 kg and a superposition size O(10)μm<Δx<O(1)nm{\cal O}(10) {\rm μm} < Δx < {\cal O}(1){\rm nm}O(10)μm<Δx<O(1)nm, respectively, in t≤0.1t\leq 0.1t≤0.1s, depending on the position we launch from the center of the diamagnetic trap. We provide an in-depth analysis of two parallel chips that can create levitation and spatial superposition along the xxx-axis, while producing a very tight trap in the yyy direction, and the direction of gravity, i.e., the zzz direction. Numerical simulations demonstrate that our setup can create a one-dimensional spatial superposition state along the x-axis. Throughout this process, the particle is stably levitated in the z-direction, and its motion is effectively confined in the y-direction for a Gaussian initial condition. This setup presents a viable platform for a diamagnetically levitated nanoparticle for a table-top experiment exploring the possibility of creating a macroscopic Schrödinger Cat state to test the quantum gravity induced entanglement of masses (QGEM) protocol.
Abstract The quantum superposition principle is a fundamental concept of physics 1 and the basis of numerous quantum technologies 2,3 . Yet, it is still often regarded counterintuitive because we do not observe its key features on the macroscopic scales of our daily lives. It is, therefore, interesting to ask how quantum properties persist or change as we increase the size and complexity of objects 4 . A model test for this question can be realized by matter-wave interferometry, in which the motion of individual massive particles becomes delocalized and needs to be described by a wave function that spans regions far larger than the particle itself 5 . Over the years, this has been explored with a series of objects of increasing mass and complexity 6–9 and a growing community aims at pushing this to ever larger limits. Here we present an experimental platform that extends matter-wave interference to large metal clusters, a qualitatively new material class for quantum experiments. We specifically demonstrate quantum interference of sodium nanoparticles, which can each contain more than 7,000 atoms at masses greater than 170,000 Da. They propagate in a Schrödinger cat state with a macroscopicity 10 of μ = 15.5, surpassing previous experiments 5,9,11 by an order of magnitude.
Abstract Every massive particle behaves like a wave, according to quantum physics. Yet, this characteristic wave nature has only been observed in double-slit experiments with microscopic systems, such as atoms and molecules [1, 2]. The key aspect is that the wavefunction describing the motion of these systems extends coherently over a distance comparable to the slit separation, much larger than the size of the system itself [3]. Preparing these states of more massive and complex objects remains an outstanding challenge. While the motion of solid-state oscillators can now be controlled at the level of single quanta, their coherence length remains comparable to the zero-point motion, limited to subatomic distances [4–7]. Here, we prepare a delocalized state of a levitating solid-state nanosphere with coherence length exceeding the zero-point motion. We first cool its motion to the ground state. Then, by modulating the stiffness of the confinement potential, we achieve more than a threefold increment of the initial coherence length with minimal added noise. Optical levitation gives us the necessary control over the confinement that other mechanical platforms lack. Our work is a stepping stone towards the generation of delocalization scales comparable to the object size, a crucial regime for macroscopic quantum experiments [8], and towards quantum-enhanced force sensing with levitated particles [9].
FINDING: Macroscopic quantum tunneling and superposition are experimentally probed via levitated nanoparticles and atom interferometry, but no new mathematical law emerges from these search results—they are experimental confirmations of existing quantum formalism. | MATH: No new equations; relies on standard Schrödinger dynamics iℏ∂tΨ=H^Ψ i\hbar \partial_t \Psi = \hat{H}\Psi iℏ∂t​Ψ=H^Ψ, tunneling probability T∼e−2γL T \sim e^{-2\gamma L} T∼e−2γL with γ=2m(V0−E)/ℏ \gamma = \sqrt{2m(V_0-E)}/\hbar γ=2m(V0​−E)​/ℏ, and decoherence rate Γ∝(mΔx)2 \Gamma \propto (m \Delta x)^2 Γ∝(mΔx)2 for macroscopic superpositions. | CONNECTION: The decoherence scaling Γ∝m2 \Gamma \propto m^2 Γ∝m2 implies a sharp transition at the Planck mass scale mP=ℏc/G≈2.176×10−8 kg m_P = \sqrt{\hbar c/G} \approx 2.176\times10^{-8}\,\text{kg} mP​=ℏc/G​≈2.176×10−8kg — a natural boundary where quantum-to-classical crossover occurs. This mass scale relates to the ratio mP/me≈2.389×1022 m_P/m_e \approx 2.389\times10^{22} mP​/me​≈2.389×1022, not directly to golden ratios. However, the levitated nanoparticle experiments operate in the 10−18 10^{-18} 10−18 to \( Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com