Measuring topology from dynamics: Chern number from a linking number (AI-generated retrospective research program, needs further hypothetical verification and physical expansion for parameters, within TDVT vacuum theory.)
In a Floquet-engineered hexagonal optical lattice of ultracold fermions, a strong quench from a topologically trivial band structure produces dynamical vortices in momentum space. The linking number between the closed trajectories of these dynamical vortices and the static Dirac-point vortices is experimentally shown to equal the ground-state Chern number CCC of the post-quench Hamiltonian. This establishes a direct, dynamical route to measure a static topological invariant and maps the Haldane-like phase diagram of the driven lattice.Nature
Rigorous mathematical framework
The bare hexagonal lattice is described by
H^0=−∑⟨l′l⟩JAB a^l′†a^l+∑l∈BΔAB n^l.\hat{H}_0 = -\sum_{\langle l'l\rangle}J_{AB}\,\hat{a}_{l'}^\dagger\hat{a}_l + \sum_{l\in B}\Delta_{AB}\,\hat{n}_l.H^0=−⟨l′l⟩∑JABa^l′†a^l+l∈B∑ΔABn^l.
Circular inertial driving at frequency ω=ΔAB/ℏ−δ\omega=\Delta_{AB}/\hbar-\deltaω=ΔAB/ℏ−δ and dimensionless strength α\alphaα generates the effective Floquet Hamiltonian
H^F=−∑⟨l′l⟩JABeffa^l′†a^l+∑⟨⟨l′l⟩⟩AJAAeffa^l′†a^l+∑⟨⟨l′l⟩⟩BJBBeffa^l′†a^l+∑l∈BΔeffn^l,\hat{H}_{\mathrm{F}} = -\sum_{\langle l'l\rangle}J_{AB}^{\mathrm{eff}}\hat{a}_{l'}^\dagger\hat{a}_l + \sum_{\langle\langle l'l\rangle\rangle_A}J_{AA}^{\mathrm{eff}}\hat{a}_{l'}^\dagger\hat{a}_l + \sum_{\langle\langle l'l\rangle\rangle_B}J_{BB}^{\mathrm{eff}}\hat{a}_{l'}^\dagger\hat{a}_l + \sum_{l\in B}\Delta^{\mathrm{eff}}\hat{n}_l,H^F=−⟨l′l⟩∑JABeffa^l′†a^l+⟨⟨l′l⟩⟩A∑JAAeffa^l′†a^l+⟨⟨l′l⟩⟩B∑JBBeffa^l′†a^l+l∈B∑Δeffn^l,
with
JABeff≃α2JABeiϕl′l,JAAeff=−JBBeff≃JAB2ℏω,Δeff=ℏδ+3JAB2ℏω.J_{AB}^{\mathrm{eff}}\simeq\frac{\alpha}{2}J_{AB}e^{i\phi_{l'l}},\qquad J_{AA}^{\mathrm{eff}}=-J_{BB}^{\mathrm{eff}}\simeq\frac{J_{AB}^2}{\hbar\omega},\qquad \Delta^{\mathrm{eff}}=\hbar\delta+3\frac{J_{AB}^2}{\hbar\omega}.JABeff≃2αJABeiϕl′l,JAAeff=−JBBeff≃ℏωJAB2,Δeff=ℏδ+3ℏωJAB2.
In the two-band pseudospin representation the quasimomentum Hamiltonian is
h(k)=h0(k)+σ⋅h(k).\mathbf{h}(\mathbf{k})=h_0(\mathbf{k})+\boldsymbol{\sigma}\cdot\mathbf{h}(\mathbf{k}).h(k)=h0(k)+σ⋅h(k).
The lowest-band Chern number is the winding of the unit vector h^(k)\hat{\mathbf{h}}(\mathbf{k})h^(k) over the Brillouin zone:
C=14π∫BZh^⋅(∂kxh^×∂kyh^) d2k.C=\frac{1}{4\pi}\int_{\mathrm{BZ}}\hat{\mathbf{h}}\cdot(\partial_{k_x}\hat{\mathbf{h}}\times\partial_{k_y}\hat{\mathbf{h}})\,d^2k.C=4π1∫BZh^⋅(∂kxh^×∂kyh^)d2k.
After a quench from a trivial initial state, the time-evolved Bloch vector ψ(k,t)\boldsymbol{\psi}(\mathbf{k},t)ψ(k,t) develops dynamical phase vortices whose trajectories form a closed contour in (kx,ky,t)(k_x,k_y,t)(kx,ky,t) space. The linking number Lk\mathrm{Lk}Lk of this contour with the static Dirac-point vortices satisfies
Lk=C.\mathrm{Lk}=C.Lk=C.
The instantaneous Chern number of the time-evolved state remains identically zero under unitary dynamics, as required by continuity of the Berry curvature under continuous evolution that never closes the gap.
Experimental verification and tested proofs
State tomography reconstructs the full Bloch vector for every k\mathbf{k}k after variable evolution times.
Vortex trajectories are tracked; their linking number with the static Dirac points is counted directly from the data.
The measured Lk\mathrm{Lk}Lk reproduces the theoretically expected Chern numbers C=0,±1C=0,\pm1C=0,±1 across the Floquet phase diagram, including the critical lines ℏδ≃−15JAB2/ℏω\hbar\delta\simeq-15J_{AB}^2/\hbar\omegaℏδ≃−15JAB2/ℏω and ℏδ≃3JAB2/ℏω\hbar\delta\simeq3J_{AB}^2/\hbar\omegaℏδ≃3JAB2/ℏω.
Instantaneous Chern-number extraction at intermediate times confirms Cinst(t)=0C_{\mathrm{inst}}(t)=0Cinst(t)=0, providing a rigorous experimental test of the topological protection of the dynamical invariant.
Convergence with TDVT / QVC
The central result—that a dynamical linking number of momentum-space vortices equals a static Chern number—maps cleanly onto the topological invariants of TDVT:
The Hopf invariant QH=1(4π)2∫A⋅(∇×A) d3rQ_H=\frac{1}{(4\pi)^2}\int\mathbf{A}\cdot(\nabla\times\mathbf{A})\,d^3rQH=(4π)21∫A⋅(∇×A)d3r of a hopfion crystal is itself a linking number of pre-images. The optical-lattice experiment supplies a laboratory realization of the same homotopy classification π3(S2)=Z\pi_3(S^2)=\mathbb{Z}π3(S2)=Z that classifies hopfions.
Quench dynamics that generate and annihilate vortex pairs while preserving a global linking number parallel the defect-mediated annealing of skyrmion/hopfion lattices: local topological defects move and annihilate, yet the global topological charge (or linking) is conserved until a gap-closing transition.
The Floquet drive that engineers a tunable Chern insulator is a concrete analogue of the external-field or current modulation used to anneal skyrmion lattices in Fe₃GaTe₂. In both cases an external periodic drive supplies the kinetic activation that allows the system to explore topological sectors while the underlying homotopy class remains invariant.
The observation that the instantaneous Chern number stays zero under unitary evolution is the dynamical counterpart of the teleparallel condition (vanishing curvature, dynamical torsion) central to TDVT: geometry is carried by the torsion sourced by topological density rather than by a non-zero instantaneous curvature.
Hypothetical ideation.
If the same quench-and-linking protocol were realized in a three-dimensional optical lattice or in a magnetic hopfion-hosting material, the measured linking number would become the Hopf index of the emerging hopfion crystal. Field-cycling protocols already demonstrated for skyrmion annealing could then be combined with Floquet engineering to prepare, detect, and stabilize ordered hopfion lattices whose collective Goldstone modes generate an Unruh–Visser acoustic metric—precisely the laboratory pathway envisioned by TDVT/QVC.
Closely related publications
Theoretical proposal of the dynamical linking-number invariant (ref. 15 of the paper).
Subsequent cold-atom measurements of Chern numbers via circular dichroism and transport in Hofstadter and Haldane models.
Experimental observation of hopfion rings in bulk FeGe (Nature 2023) and construction of hopfion crystals (arXiv:2504.03981).
Field- and strain-driven annealing of skyrmion lattices in van-der-Waals magnets (Nat. Commun. 2026 and Adv. Mater. 2025).
Together these works establish a continuous experimental and theoretical thread from dynamical measurement of Chern numbers, through defect-mediated ordering of topological solitons, to the controlled realization of hopfion crystals that can host analogue spacetime.
TABD - Topological Acoustic Bubble Drive: An In-Depth explanation of core mechanisms, dynamics, and metrics/parameters. A framework I have been working on for a while; it is an engineering protocol for what is hopefully the foundations for how a warp drive and torsional propulsion would function.
Video was made with SVG animated graphics from Claude models.
Replying to @NPC__3PO
I've written a long and in-depth manuscript on it, complete with verifications, computational suites, and extensive derived parameters and datasets. What papers have you contributed to physics?
Real neural stokes quantum informational biology simulation within my TDVT-Psi brain dynamic framework. Could this be the basis for spacetime topology-based informational consciousness and brain function within a lattice model? Possibly, it is interesting to work on this and see the bridge between theoretical physics and quantum phenomena, to inside the brain. Speculative, but promising results based on computed neural modeling from various university/lab datasets.
First Quant Paper Drop in a while, analysis of interesting converging papers with my research:
Field-driven annealing of skyrmion lattices in Fe₃GaTe₂ — and its convergence with QVC/TDVTResearchers have achieved non-thermal annealing of topological skyrmion lattices in the room-temperature van der Waals ferromagnet Fe₃GaTe₂ (FGaT). Starting from a disordered, liquid-like assembly of Néel-type skyrmions, oscillating out-of-plane magnetic fields produce polycrystalline hexagonal lattices with well-defined grain boundaries, while bipolar current pulses generate anisotropic hexatic states whose orientation aligns with the current. Both pathways proceed via defect-mediated crystallization (annihilation and coarsening of 5–7 coordinated defects), enabled by the interplay of Dzyaloshinskii–Moriya interaction (DMI) and magnetocrystalline anisotropy (MA), with dipolar interactions dominating the thermodynamics.NatureThis is the first clear experimental realization of field-annealable quasiparticle crystals at ambient conditions.Core micromagnetic descriptionThe free-energy density that stabilizes the skyrmions is$$E = A\,(\nabla\mathbf{m})^2 + D\,\mathbf{m}\cdot(\nabla\times\mathbf{m}) - K\,(\mathbf{m}\cdot\hat{z})^2 - \mu_0 M_s\mathbf{m}\cdot\mathbf{H} + E_{\mathrm{dip}},$$where $A$ is the exchange stiffness, $D$ the interfacial DMI strength (arising from Fe vacancies), $K$ the uniaxial anisotropy, and $E_{\mathrm{dip}}$ the long-range dipolar term. The topological charge of each skyrmion is the integer$$Q = \frac{1}{4\pi}\int\mathbf{m}\cdot(\partial_x\mathbf{m}\times\partial_y\mathbf{m})\,d^2r = \pm 1.$$Local hexagonal order is quantified by the bond-orientational order parameter$$\Psi_6(\mathbf{r}_j) = \frac{1}{N_j}\sum_{k=1}^{N_j}e^{i6\theta_{jk}},$$with global averages $\langle|\Psi_6|\rangle$ tracking the liquid $\to$ hexatic $\to$ polycrystalline progression under cycling.Monte-Carlo simulations of the same Hamiltonian confirm that pure thermal activation cannot surmount the MA-induced barriers at 300 K; external-field modulation is required to supply the kinetic energy for defect motion while preserving $Q$.Convergence with Quantum Vacuum Catalyzation / Topological Dynamic Vacuum TheorySkyrmions ($\pi_2(S^2)=\mathbb{Z}$) are the two-dimensional topological precursors of the hopfions ($\pi_3(S^2)=\mathbb{Z}$) that form the crystal lattice in TDVT. The field-annealing protocol demonstrated here supplies a concrete laboratory analogue of the “vacuum freeze” and ordered-lattice formation central to QVC/TDVT:
Defect-mediated coarsening of 5–7 dislocations maps onto the annihilation of Hopf-charge defects that sources axial Cartan torsion in the teleparallel sector of TDVT.
Current-induced uniaxial strain that selects a preferred lattice orientation is the experimental counterpart of the democratic hybridization $G=g_0(J-I)$ that gaps the Goldstone spectrum and locks the vacuum factor $\mathcal{F}$.
The resulting low-defect hexagonal (or hexatic) lattice is precisely the elastic medium whose phase fluctuations generate an Unruh–Visser acoustic metric; residual dislocations become candidate sources of effective torsion, while the ordered lattice itself supports the analogue horizons and surface gravity $T_H=\kappa/2\pi$.
Because FGaT operates at room temperature and responds to both magnetic and electric drives, it offers an immediately accessible 2D test-bed for the annealing, ordering, and transport signatures (anomalous Hall conductivity, thermal Hall of magnetorotons, torsion-shifted magnon gaps) predicted by TDVT for three-dimensional hopfion crystals.
In short, the experiment realizes, in a concrete material, the preparatory step that TDVT requires: controlled conversion of a disordered topological liquid into a stable, low-defect ordered lattice whose collective modes can host emergent geometry. Extending the same field-cycling protocols to thicker or multilayer stacks that support hopfion-like textures would furnish a direct experimental bridge from 2D skyrmion annealing to the 3+1-dimensional hopfion vacuum of QVC/TDVT. Found this intriguing with many connections and shared foundations within my frameworks.
Citations: advanced.onlinelibrary.wiley… and other similar mat. sci and condensed matter publications
Replying to @zpfTechnologies
Interesting. Looks like a self-organizing lattice dusty plasma where information forms a spiral geometry.
Replying to @Akitti
Lattice BKT transition in photonic metamaterial, from this paper, connection to the arxiv paper you sent, this can also occur in a moire lattice, found some interesting publications with convergence to some of my work on mat science and possibly yours as well. onlinelibrary.wiley.com/doi/… nature.com/articles/s41467-0…
Replying to @Akitti
My neat and interesting grok bot configuration, giving them a profile of an actual figure seems to help with the agentic workflow for some weird reason

















