Universal Scaling of Many-Body Quantum Tunneling ✛
Context
Quantum tunneling underlies many phenomena: from thermonuclear fusion in stars and Big Bang nucleosynthesis to the operation of scanning tunneling microscopes and flash memory. However, with the development of superconducting technologies and quantum computing, many-body tunneling processes have come to the fore, such as macroscopic tunneling of Cooper pairs in Josephson junctions. Until now, it remained unclear how the interaction between particles changes the fundamental scaling law for the critical tunneling barrier with temperature change — a question directly relevant to organic superconductors and high-temperature materials.
Methods
The experimentalists prepared a Bose-Einstein condensate of rubidium-87 atoms and loaded it into a three-dimensional optical lattice formed by laser beams (quantum optics). By changing the polarization of the beams, they switched between hexagonal and triangular geometries of the two-dimensional lattice, and by varying the intensity, they controlled the tunneling coupling. The temperature and number of atoms were adjusted independently. The critical lattice depth at which tunneling vanishes was determined through the fraction of zero momentum in quantum measurement of the momentum distribution after ballistic expansion. The system dynamics was described by Schrödinger's equation with the Lieb-Liniger Hamiltonian, and the macroscopic state of the condensate obeyed Bose–Einstein statistics.
Results
In the quantum regime, below the Bose condensation temperature, a universal power-law dependence of the critical tunneling matrix element Jc ~ T^α was discovered. For weak interactions, the exponent α ≈ 2, which matches predictions of mean-field theory for a Luttinger liquid. Verification at different particle numbers (1–3×$10^5$), longitudinal lattice depths (0 and 5 Er), and both geometries showed that all data fall onto a single line on a log-log scale after proper renormalization, confirming universality with α = 1.96(6). In the classical regime, the critical lattice depth Vc grew linearly with temperature, as expected from equipartition of energy. Using numerical simulations with the quantum Monte Carlo method, the applicability of the one-dimensional description was confirmed. With increasing longitudinal potential V1D, the effective interaction increased, and α gradually decreased, following the theoretical curve α = (4K−1)/(2K) (where K is the Luttinger parameter). In the limit V1D ≥ 60 Er, the exponent reached unity, meaning a transition to single-particle tunneling. Thus, a continuous crossover from collective to individual behavior was observed.
Implications
The results prove for the first time that many-body effects drastically renormalize quantum tunneling and that the scaling Jc ~ T^α with non-integer α is universal for a broad class of systems. This deepens the understanding of the role of interactions in low-dimensional quantum systems and lays the groundwork for engineering tunneling properties in superconducting devices and quantum information platforms.
Future development
In the future, the proposed approach could be extended to fermionic systems, which is particularly relevant for organic superconductors and high-temperature cuprates, where tunneling between one-dimensional chains plays a key role. Another direction is testing the universality of scaling in astrophysical and biological tunneling processes, where many-body effects may also be significant.
Impact
Condensed matter physics, quantum computing, superconducting electronics, astrophysics.
Next steps
Measuring scaling for stronger interactions up to the fermionic regime and studying the role of dimensionality at the 2D–1D transition.
Key open problems
Mechanism of high-temperature superconductivity, many-body problem in non-equilibrium conditions, fundamental limits of quantum tunneling in complex media.
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 paper experimentally investigates many-particle quantum tunneling of a Bose condensate in an optical lattice. The authors measured a universal power-law dependence of the critical tunneling matrix element on temperature and demonstrated a crossover from collective to single-particle behavior as the interaction strength is varied.
Where its strength is
The strength of the work lies in the direct experimental confirmation of the universal scaling with exponent α ≈ 2 for weak interactions and in the observation of a continuous crossover governed by the Luttinger parameter.
Where it could go next
- It might be interesting to see how the discovered universality manifests under non-equilibrium conditions, for instance, upon a sudden change of lattice parameters. Nearby in the archive there is a review of a work on quantum engines that considers controlling quantum systems via measurements.based on: Quantum Engines Powered by a Look arXiv:2510.22394
- A possible extension is to study tunneling in systems with more complex geometry or with additional internal degrees of freedom, such as spin. In the archive, there is a work on tunneling of a spinning particle, which discusses the influence of rotational degrees of freedom on the tunneling process.based on: A Tunnel for a Spinning Particle arXiv:2608.05511v1
- Another avenue is to consider the connection of the discovered scaling with phenomena in solid-state physics, for example, high-temperature superconductivity. In the archive, there is a quick review on how the geometry of electronic orbitals can lead to superconductivity, which may provide a bridge to interpreting the results.based on: How the Geometry of Electron Orbits Gives Rise to Superconductivity arXiv:2606.21166
Worth trying
- Test whether the universal scaling persists under a sudden switch-on of the tunneling coupling (quantum Kibble-Zurek).
- Investigate tunneling in a two-dimensional lattice with the addition of synthetic spin-orbit coupling.
- Compare experimental data with predictions for strongly interacting fermions in a similar geometry.
Why this may matter
Understanding many-particle tunneling could aid in the development of new quantum devices, such as atom interferometers and high-precision sensors, and also shed light on mechanisms in strongly correlated materials.
Nearby works in our archive
- Quantum Engines Powered by a Looksimilarity 0.66
- The Quantum Ghost of the Passsimilarity 0.65
- Lightning and Quantum Avalanches: One Signaturesimilarity 0.64
- A Tunnel for a Spinning Particlesimilarity 0.64
- The Edge of Time: How an Instant Turns a Quantum into a Frozen Wavesimilarity 0.64
- Motion as Fuel: Quantum Engines at Near-Light Speedssimilarity 0.64
- How the Geometry of Electron Orbits Gives Rise to Superconductivitysimilarity 0.63
The closest work in the archive sits at 0.66 by meaning — the usual level for our corpus.
Original abstract
as written by the authors arXiv:2606.31659
Quantum tunneling is fundamental to diverse phenomena and underpins a wide range of modern technologies. In the study of superconducting quantum computation and high-temperature superconducting materials, tunneling on multi-particle scale is central. Recently, several cold atom experiments successfully simulated the tunneling process in a many-particle ensemble. However, the many-body nature remains largely unexplored. Here, we observe the universal scaling of many-body effects in quantum tunneling process, using a hexagonal-triangular quantum simulator with independent control of barrier, temperature and interaction. In the weak-interaction regime, the critical tunneling coefficient scales parabolically with temperature under various conditions, in contrast to the linear scaling of single-particle tunneling. By further increasing the interactions beyond the mean-field regime, the scaling exponent decreases, consistent with quantum field theory predictions. Our results address the fundamental question of how many-body effects renormalize quantum tunneling, with direct implications for correlated quantum matter and devices.
The transition from collective to single-particle tunneling with increasing lattice depth resembles how a crowd of people going through a narrow door changes its behavior under a strong crush: interaction makes everyone 'feel' each other, but when the passage becomes too tight, each one squeezes through on their own.
Key numbers
- Typical condensate temperature: 20–150 nK
- Exponent α in the weakly interacting regime: ≈1.9–2.1
- Number of atoms in the condensate: 1×105 – 3×105
- Critical temperature of Bose condensation: ≈250 nK
- Lattice constant in the longitudinal direction: 532 nm