Vortices on the Quantum Stage ✛ ✎

Original: "Simulating fluid vortex interactions on a superconducting quantum processor"
arXiv:2506.04023v1 · 2025-06-04 · arXiv non-exclusive · independent analysis · 3 min
A superconducting quantum processor has, for the first time, reproduced the interaction of vortices in a fluid, without a grid and without intermediate measurements.

Context

Classical calculations of vortex interactions hit a wall in computational resources: you need to resolve fine details and track long-term evolution simultaneously. Neighboring works have already tried to port hydrodynamics to quantum computers, using lattice methods, Schrödinger equations, or hybrid schemes, but complex vortex phenomena remained out of reach. This work follows the line of quantum algorithms for partial differential equations, but takes a step toward directly describing vortices rather than the whole grid.

Methods

The authors took the classical vortex method, where the fluid is described by a set of point vortices, and rewrote it as a Schrödinger equation with an effective Hamiltonian. Vortex positions are encoded in the amplitudes of the wavefunction, and time is encoded in additional qubits prepared in superposition. Controlled evolution operators, trained on a short segment of classical simulation, act on the spatial qubits depending on the state of the temporal ones. Thus, a single run of the circuit yields the entire history of the system. The experiment was performed on eight qubits of a superconducting processor with single-qubit gate fidelity of 99.97% and two-qubit fidelity of 99.76%.

Results

For a system of four vortices mimicking two vortex rings, the quantum method reproduced the leapfrogging effect, where the rings alternately pass through each other. The overlap with the ideal simulation exceeded 97% in state fidelity, and vortex position deviations remained below 0.2 throughout the evolution. The reconstructed velocity fields matched the calculated ones. For an eight-vortex turbulent system, numerical simulation on the MindQuantum platform showed stable dynamics with preservation of coherent structures. In the viscous case, the quantum method accurately tracked the evolution of two vortices, while the classical Lagrangian method showed noticeable deviations.

Implications

This work shows that a quantum computer can directly manipulate vortices as objects, not as perturbations on a grid. This differs from neighboring approaches that either require high spatial discretization or suffer from state collapse when measuring at each step. Here, temporal superposition removes the need to re-prepare the state, and the vortex description drastically reduces the number of qubits. This is the first experimental demonstration of a quantum vortex method on real hardware for nonlinear interactions.

Future development

The method could be extended to more vortices and three-dimensional flows. Improved quantum gates, error correction, and more efficient tomography will allow scaling up simulations. It might also be combined with hybrid quantum-classical schemes to compute turbulence at high Reynolds numbers.

Impact

The results could impact computational fluid dynamics, meteorology, oceanography, and plasma physics, wherever vortex structures matter. The method also opens new ways to encode dynamical data in quantum memory.

Next steps

Immediate next steps are extending to three-dimensional vortex rings, incorporating viscosity in multi-vortex systems, and reducing noise through error correction. It would be useful to compare with classical vortex methods on problems where they perform well.

Key open problems

For hydrodynamics, the exact description of the energy cascade in turbulence and the role of coherent vortex structures remains an open question. The quantum vortex method could provide a new tool for testing hypotheses about vortex interactions, but its applicability to real turbulent flows has yet to be proven.

The knowledge machine's view

This section is addressed to the author of the paper and their colleagues. Neighbouring works were found by meaning-based search across our archive, not by word overlap. We do not review: we show the field around the work.

What the work does

The authors recast the classical vortex method in a quantum-mechanical form, encoding vortex positions and time in a single quantum state, and ran it on eight qubits of a superconducting processor. They reproduced the leapfrogging effect for two vortex rings and the dynamics of a turbulent system, demonstrating high state fidelity and agreement of velocity fields.

Where its strength is

The method yields the entire time evolution in a single circuit run, avoiding intermediate measurements and repeated state preparation, which substantially reduces resource requirements compared to step-by-step approaches.

Where it could go next

Worth trying

  • Test the scaling of the method to more vortices and qubits, using ideas from the work on quantum turbulence.
  • Try to incorporate viscosity via non-Hermitian terms in the effective Hamiltonian, building on experience with shock waves in liquid light.
  • Check the method's applicability to superfluid vortices by adding quantum circulation as in the work on a vortex with memory.

Why this may matter

If the vortex method can be extended to more complex flows and a larger number of vortices, it could pave the way for quantum simulation of hydrodynamics in regimes inaccessible to classical computers, including turbulence and superfluidity.

The leapfrogging of vortex rings was first observed back in the 19th century: two smoke rings released one after the other alternately pass through each other, swapping places. Now this dance has been reproduced on a quantum processor.

In Liu Cixin's novel "The Three-Body Problem," aliens use vortex structures to control weather. Quantum simulation of vortices is a step toward understanding such extreme hydrodynamic scenarios.

Key numbers

  • qubits: 8
  • single-qubit gate fidelity: 99.97%
  • two-qubit gate fidelity: 99.76%
  • state fidelity: >97%
  • vortex position deviation: <0.2
Scientists
Klaus von KlitzingLev LandauDaniel BernoulliLeonhard EulerAlexander HolevoAsher Peres
Concepts
quantum simulation of physical systems quantum simulator computational fluid dynamics hydrodynamic simulation Navier-Stokes equations Water hybrid approach computational method memory single qubit operation feynman droplet superfluid vortex magnetic vortex hybrid algorithm data center virtual particle complexity gate voltage molecular dynamics acceleration