arXiv subjects

Qian Xiang

Publications and source records attributed to Qian Xiang.

10 recordsLinked to original sources

arXiv2026

Magnetic levitation and spatial superposition of a nanodiamond with a current-carrying chip

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 versatile, for a mass range of $10^{-19}~{\rm kg}\leq m\leq 10^{-17}~{\rm kg}$ a superposition size of range ${\cal O}(100){\rm nm} < Δx < {\cal O}(10) {\rm μm}$ is achievable in $t\leq 0.1$s, depending on the position we launch from the centre of the diamagnetic trap. Using numerical simulations, we provide an in-depth analysis of the chip that can support stable trapping of the particle in all three dimensions as well as create a spatial superposition along the $x$-axis, while producing a very tight trap in the transverse directions. This setup enables the creation of a Schrödinger cat state with a diamagnetically levitated nanoparticle in a table-top experiment. Although the mass and superposition size considered here remain below those required for a QGEM test, the proposed device provides a building block toward future QGEM experiments.

quant-ph↗

arXiv2026

A Computational Journey Toward an Optimal Design for Metamaterial Epicardial Passive Sleeves

Heart failure (HF) following myocardial infarction (MI) is a major clinical challenge with severe complications. Epicardial sleeves and patches are increasingly investigated to improve heart function post-MI, yet their passive mechanical effects remain underexplored. This has resulted in limited insight into how sleeves mechanically interact with the infarct and remote myocardium. This study used 3-D in-silico cardiac models to examine how sleeve shape, material properties, and architecture affect global and regional mechanics. A high-fidelity biventricular model is used to investigate how a continuum cardiac sleeve alters function. Designs that improve regional mechanics successfully limited pathological bulging, modulated fiber strains, and influenced torsional behavior without over-constraining remote tissue, whereas overly restrictive and stiff sleeves penalized healthy myocardium and reduced the intended relief of infarct bulging. These findings highlight the importance of considering regional biomechanical markers when developing sleeve designs. Building on these continuum sleeve insights, a spheroidal left ventricle model demonstrated the proof-of-concept advantage of an "auxetic" metamaterial sleeve, engineered with a negative Poisson ratio. This programmed architecture provided region-specific benefits beyond those of conventional continuum sleeves. Ultimately, this work contributes to an improved understanding of passive sleeve-heart interactions and improves the targeted biomechanical support therapies following MI.

physics.med-ph↗

arXiv2026

Smell with Genji: Rediscovering Human Perception through an Olfactory Game with AI

Olfaction plays an important role in human perception, yet its subjective and ephemeral nature makes it difficult to articulate, compare, and share across individuals. Traditional practices like the Japanese incense game Genji-ko offer one way to structure olfactory experience through shared interpretation. In this work, we present Smell with Genji, an AI-mediated olfactory interaction system that reinterprets Genji-ko as a collaborative human-AI sensory experience. By integrating a game setup, a mobile application, and an LLM-powered co-smelling partner equipped with olfactory sensing and LLM-based conversation, the system invites participants to compare scents and construct Genji-mon patterns, fostering reflection through a dialogue that highlights the alignment and discrepancies between human and machine perception. This work illustrates how sensing-enabled AI can participate in olfactory experience alongside users, pointing toward new possibilities for AI-supported sensory interaction and reflection in HCI.

cs.HC↗

arXiv2025

A Spin-Based Pathway to Testing the Quantum Nature of Gravity

A key open problem in physics is the correct way to combine gravity (described by general relativity) with everything else (described by quantum mechanics). This problem suggests that general relativity and possibly also quantum mechanics need fundamental corrections. Most physicists expect that gravity should be quantum in character, but gravity is fundamentally different to the other forces because it alone is described by spacetime geometry. Experiments are needed to test whether gravity, and hence space-time, is quantum or classical. We propose an experiment to test the quantum nature of gravity by checking whether gravity can entangle two micron-sized crystals. A pathway to this is to create macroscopic quantum superpositions of each crystal first using embedded spins and Stern-Gerlach forces. These crystals could be nanodiamonds containing nitrogen-vacancy (NV) centres. The spins can subsequently be measured to witness the gravitationally generated entanglement. This is based on extensive theoretical feasibility studies and experimental progress in quantum technology. The eventual experiment will require a medium-sized consortium with excellent suppression of decoherence including vibrations and gravitational noise. In this white paper, we review the progress and plans towards realizing this. While implementing these plans, we will further explore the most macroscopic superpositions that are possible, which will test theories that predict a limit to this.

quant-ph↗

arXiv2025

Spin-Dependent Force and Inverted Harmonic Potential for Rapid Creation of Macroscopic Quantum Superpositions

Creating macroscopic spatial superposition states is crucial for investigating matter-wave interferometry and advancing quantum sensor technology. Currently, two potential methods exist to achieve this objective. The first involves using inverted harmonic potential (IHP) to spatially delocalize quantum states through coherent inflation [1]. The second method employs a spin-dependent force to separate two massive wave packets spatially [2]. The disadvantage of the former method is the slow initial coherent inflation, while the latter is hindered by the diamagnetism of spin-embedded nanocrystals, which suppresses spatial separation. In this study, we integrate two methods: first, we use the spin-dependent force to generate initial spatial separation, and second, we use IHP to achieve coherent inflating trajectories of the wavepackets. This approach enables the attainment of massive large spatial superposition in minimal time. For instance, a spatial superposition with a mass of $10^{-15}$ kg and a size of 50 $μ$m is realized in $0.1$ seconds. We also calculate the evolution of wave packets in both harmonic potential (HP) and IHP using path integral approach.

quant-ph↗

arXiv2024

Phonon-induced contrast in a matter-wave interferometer

Utilizing the Stern-Gerlach apparatus to create matter-wave superposition states is a long-sought-after goal, not only due to its potential applications in the quantum realm but also because of its fundamental implications for studying the quantum properties of gravity. The main challenge in creating a macroscopic quantum interferometer arises from the loss of coherence, primarily through two channels. One channel involves strong coupling with the environment for macroscopic matter, leading to decoherence. The other channel relates to the precision of wave packet overlap, which can occur due to external and internal fluctuations of various sources. The latter introduces a unique challenge for larger-scale masses by perturbing the centre of mass motion of the macroscopic object. Here, we study a particular challenge, namely, the issue of internal degrees of freedom, specifically phonon fluctuations and contrast reduction. This work will investigate the contrast reduction caused by spin-magnetic field and diamagnetic interactions at the phonon occupation level in the quantum gravity-induced entanglement of masses (QGEM) protocol configuration.

quant-ph↗

arXiv2022

Spontaneously translational symmetry breaking in the excited states of holographic superconductor

We revisit HHH model in [Phys. Rev. Lett. {\bf 101}, 031601 (2008)] and extend the ansatz of matter fields to being of depending on a spatial dimension except the holographic direction. Despite homogeneous solutions of ground and excited states, especially for the excited states, there also exists solutions where the translational invariance is broken. It is worth mentioning that no periodic sources are assigned to the matter fields, so the translational symmetry is broken spontaneously. We investigate how the new solutions and the condensates of excited states develop with the change of temperature. Moreover, since this kind of condensate will decrease at certain temperature and eventually vanish at sufficiently low temperature, we also study the relation between this interval and length of lattice. Besides, we compare the free energies of non-translational invariant solutions and those of translational invariance in the HHH model, and find that the free energies of the former situations are lower.

hep-th↗

arXiv2020

Flat and bent branes with inner structure in two-field mimetic gravity

Inspired by the work [Eur. Phys. J. C 78 (2018) 45], we study the linear tensor perturbation of both the flat and bent thick branes with inner structure in two-field mimetic gravity. The master equations for the linear tensor perturbations are derived by taking the transverse and traceless gauge. For the Minsowskii and Anti-de-Sitter brane, the brane systems are stable against the tensor perturbation. The effective potentials of the tensor perturbations of both the flat and bent thick branes are volcano-like, and this structure may potentially lead to the zero-mode and the resonant modes of the tensor perturbation. We further illustrate the results of massive resonant modes.

hep-th↗

arXiv2020

Excited states of holographic superconductors from massive gravity

In this paper, we generalize the study of the model of holographic superconductor in the excited states to the framework of massive gravity. By taking into account the effect of massive graviton, we numerically present a family of solutions of the holographic superconductor in excited states, and find that the critical temperatures can be higher due to the effect of massive graviton comparing with the superconductor in Einstein gravity. We also investigate the condensates and conductivities in the ground state and the excited states with studying various parameters that determine the framework of gravity background.

hep-th↗

arXiv2020

Holographic flows with scalar self-interaction toward the Kasner universe

Considering a thermal state of the dual CFT with a uniform deformation by a scalar operator, we study a holographic renormalization group flow at nonzero temperature in the bulk described by the Einstein-scalar field theory with the self-interaction term $λϕ^4$ in asymptotic anti-de Sitter spacetime. We show that the holographic flow with the self-interaction term could run smoothly through the event horizon of a black hole and deform the Schwarzschild singularity to a Kasner universe at late times. Furthermore, we also study the effect of the scalar self-interaction on the deformed near-singularity Kasner exponents and the relationship between entanglement velocity and Kasner singularity exponents at late times.

hep-th↗