Periodically driven quantum systems should thermalize. You shake a quantum system at a fixed frequency (Floquet driving), and the standard expectation is that the system absorbs energy from the drive, heats up, and approaches a featureless infinite-temperature state. Thermalization is the second law applied to driven systems: order degrades, energy spreads, structure dissolves.
A 2026 study (PRX, Cornell) shows this expectation fails in a specific, calculable way. Certain Floquet-driven systems remain ordered for timescales that are not just long but astronomically long — the instanton-mediated transition to thermalization is suppressed so severely that the prethermal lifetime exceeds all laboratory timescales and approaches cosmic ones. Not a violation of the second law, but a delay so extreme it is functionally indistinguishable from one.
The mechanism is instanton suppression. In quantum field theory, instantons are tunneling events that connect different configurations of a system. For the Floquet system to thermalize, it needs to tunnel from its ordered prethermal state to the disordered thermal state. The study shows that the tunneling rate can be computed from first principles, and for certain parameter values, the rate is suppressed to the point where the lifetime of the ordered state becomes predictable — and enormous.
The system sits in what the authors describe as “a finely balanced state, poised between order and chaos.” This is not metastability in the usual sense. A metastable state (a ball sitting in a shallow valley) can be dislodged by thermal fluctuations. The prethermal Floquet state resists thermalization because the tunneling pathway is suppressed by the drive itself. The periodic shaking that should destroy order instead stabilizes it, by making the escape route exponentially unlikely.
The prediction is quantitative: given the drive parameters, you can calculate the prethermal lifetime. This moves the phenomenon from “sometimes things stay ordered longer than expected” to “here is the formula for how long order persists.” The formula says: for the right drive parameters, the answer is effectively forever.
For quantum computing, the implication is a mechanism for decoherence-resistant storage. Quantum information stored in a periodically driven system could be protected not by isolation from the environment (the standard approach) but by driving the system in a way that suppresses the transition to thermal equilibrium. The drive doesn't just maintain the state — it actively prevents the escape pathways that would destroy it.
The broader principle is that driving a system at the right frequency doesn't always heat it. It can freeze it. The same energy input that destabilizes most systems stabilizes this one, because the drive's effect on the tunneling landscape is to close the routes through which order decays. Thermalization requires specific pathways, and periodic driving can block them. The result is a system that is continuously pumped with energy but never heats up — eternal motion without entropy production, until the instantons finally find a way through.