Emergent hydrodynamics in a strongly interacting dipolar spin ensemble

Abstract

Conventional wisdom holds that macroscopic classical phenomena naturally emerge from microscopic quantum laws (1-8). However, despite this mantra, building direct connections between these two descriptions has remained an enduring scientific challenge. In particular, it is difficult to quantitatively predict the emergent "classical" properties of a system (e.g. diffusivity, viscosity, compressibility) from a generic microscopic quantum Hamiltonian (8-19).Here, we introduce a hybrid solid-state spin platform, where the underlying disordered, dipolar quantum Hamiltonian gives rise to the emergence of unconventional spin diffusion at nanometer length scales. In particular, the combination of positional disorder and on-site random fields leads to diffusive dynamics that are Fickian yet non-Gaussian (20-26). Finally, by tuning

Quantum gas microscopy of Kardar-Parisi-Zhang superdiffusion

“…As depicted in Fig. 2A, the data exhibit a superdiffusive exponent, z = 1.54 (7), consistent with KPZ scaling. By comparison, neither a diffusive (z = 2) nor ballistic (z = 1) exponent accurately capture the observed dynamics (Fig.…”

“…To explore the nature of anomalous spin transport in the 1D Heisenberg model, we initialize the spins in a high-entropy domain-wall state with η = 0.22. We characterize the subsequent spin transport by measuring the The polarization transfer for a domain-wall initial state with a contrast of η = 0.22 grows as a power law (P (t) ∝ t 1/z ) with a fitted exponent z = 1.54 (7) (solid line), indicating superdiffusive transport. The experimental data agrees well with numerical Heisenberg-model simulations (dashed line).…”

“…Hydrodynamics captures the evolution of a system from local to global equilibrium [1,2]. In many-particle systems, the conventional lore is that-upon coarsegraining-such hydrodynamics naturally emerges from the microscopic equations of motion of both classical and quantum systems [3][4][5][6][7]. A celebrated example of the emergence of hydrodynamics is the so-called Kardar-Parisi-Zhang (KPZ) equation, which governs a wealth of disparate phenomena ranging from interface growth to the shapes of polymers and the propagation of shock waves [8][9][10].…”

“…Superdiffusive spin transport in a high-temperature Heisenberg chain. (A) The polarization transfer for a domain-wall initial state with a contrast of η = 0.22 grows as a power law (P (t) ∝ t 1/z ) with a fitted exponent z = 1.54(7) (solid line), indicating superdiffusive transport. The experimental data agrees well with numerical Heisenberg-model simulations (dashed line).…”

Emergent decoherence induced by quantum chaos in a many-body system: A Loschmidt echo observation through NMR

“…The last two decades have shown a growing interest on the understanding of how the classical limit [1], thermalization [2] and hydrodynamic behavior [3,4] emerge from quantum dynamics in closed many-body systems [5][6][7][8][9][10]. This interest is driven by new quantum technologies ranging from hetero-structures to cold atoms, NV and P1 centers in diamond, Bose-Einstein condensates, and a number of others [11][12][13][14][15][16].…”