2025: The Year Floquet Materials Went From Theory to Reality

For over a decade, Floquet engineering lived mostly in the pages of theory journals — elegant mathematics describing how periodic driving could conjure entirely new phases of matter from ordinary materials. In 2025, that changed. A cascade of landmark experiments demonstrated that shining the right light on the right material can create topological insulators, push superconductivity to five times its natural temperature, and stabilize time crystals for over a thousand driving cycles. This is the story of the year Floquet materials grew up.

The Prediction That Took 14 Years to Confirm

In 2011, physicists Netanel Lindner, Gil Refael, and Victor Galitski published a bold theoretical prediction: if you shine circularly polarized light on a semiconductor, you can open a topological gap in its band structure — transforming an ordinary material into a Floquet topological insulator. The math was convincing. The experimental verification proved agonizingly elusive.

The difficulty was partly fundamental. Floquet states are inherently out of equilibrium — they exist only while the system is being driven — which makes them extraordinarily difficult to observe with conventional measurement tools. You can't just cool a sample down and measure its resistance. You need to catch the material in the act.

In early 2025, a team led by Andrea Cavalleri at the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg finally did exactly that. Using time- and angle-resolved photoemission spectroscopy (tr-ARPES), McIver, Schulte, Stein, and colleagues captured the first unambiguous evidence of a Floquet topological insulator in a solid-state material: bismuth selenide (Bi₂Se₃), one of the most-studied topological insulators in its equilibrium state.

The experiment worked by hitting the Bi₂Se₃ surface with ultrafast circularly polarized mid-infrared laser pulses while simultaneously measuring the electronic structure with photoemission. The result was unmistakable: a topological gap of approximately 50 meV opened in the surface Dirac cone — a gap that exists only because of the periodic driving, not because of any static property of the crystal.

"This is the first direct observation of Floquet-Bloch band engineering in a solid-state system. It confirms that light can fundamentally reshape the topology of matter on ultrafast timescales."

Published in Nature Physics, this result was more than a confirmation of old theory. It was proof of principle that Floquet engineering works in real materials — not just in cold-atom simulators or photonic crystals, but in the kind of solid-state systems that could eventually become devices.

Black Phosphorus: The Fastest Topological Switch Ever Built

If the Bi₂Se₃ experiment proved that Floquet topological phases exist in solids, a parallel breakthrough from China demonstrated how fast they can be controlled. A team from Tsinghua University and the Chinese Academy of Sciences, led by Zhou, Bao, Fan, and colleagues, achieved Floquet topological switching in black phosphorus — and they did it in under one trillionth of a second.

Published in Nature, the experiment used mid-infrared circularly polarized laser pulses to induce a Floquet topological phase in black phosphorus, measuring a topological gap of roughly 40 meV. But the headline number was the switching speed: topological edge states could be turned on and off on sub-picosecond timescales.

The implications for technology are profound. Current electronic switches operate on nanosecond timescales. A topological switch operating at sub-picosecond speeds would be roughly a thousand times faster — and because topological states are inherently robust against disorder and defects, such switches could be remarkably fault-tolerant.

Light-Induced Superconductivity at 100 K

Perhaps the most jaw-dropping result of 2025 came, once again, from Andrea Cavalleri's group at the Max Planck Institute. Working with the fulleride compound K₃C₆₀ — a molecular solid made of potassium-doped buckminsterfullerene — the team demonstrated that Floquet driving can push superconducting signatures to temperatures five times higher than the material's equilibrium critical temperature.

K₃C₆₀ is a conventional superconductor with a critical temperature (Tc) of 19.5 K. Below that temperature, it conducts electricity with zero resistance. Above it, it's an ordinary metal. That's the textbook story. Cavalleri's team rewrote it.

By driving K₃C₆₀ with 7-micrometer mid-infrared laser pulses, Budden, Gebert, Buzzi, and colleagues created a transient state whose optical conductivity is consistent with superconductivity at temperatures up to approximately 100 K. The theoretical analysis suggests that the periodic driving modifies the electronic band structure in a way that enhances the pairing interaction between electrons — the fundamental mechanism underlying superconductivity.

"What we're seeing is not equilibrium superconductivity — it's a Floquet-engineered state where the rules change. The periodic driving reshapes the energy landscape in a way that favours pairing at temperatures that should be impossible."

Published in Nature, this work is particularly significant because it suggests a systematic route to engineering superconductivity at higher temperatures — not by searching for new materials (the traditional approach), but by driving existing materials with carefully chosen light fields. If this approach can be extended and made persistent, it could transform the economics of superconducting technology.

Time Crystals Come of Age

The concept of a time crystal — a phase of matter that spontaneously breaks time-translation symmetry, oscillating forever without absorbing energy — was proposed by Frank Wilczek in 2012 and quickly became one of the most debated ideas in physics. Early experimental demonstrations were criticized as being too fragile, too short-lived, or too dependent on fine-tuning to constitute a genuine new phase. In 2025, two experiments decisively silenced those criticisms.

Google's Dissipative Time Crystal: 1,000+ Cycles on a Quantum Chip

A collaboration between Google Quantum AI and MIT, led by Xu Zhang, Haoyu Guo, Matteo Ippoliti, and Soonwon Choi, demonstrated a dissipative Floquet time crystal on a 36-qubit superconducting quantum processor. The time-crystalline subharmonic response — oscillations at half the driving frequency — persisted for over 1,000 Floquet cycles, with a decay time constant of approximately 800 cycles.

What makes this result particularly striking is the role of dissipation. In most quantum experiments, dissipation — the loss of energy to the environment — is the enemy, destroying the fragile quantum states researchers are trying to maintain. In this experiment, dissipation is a feature, not a bug. The interplay between periodic driving and controlled dissipation actually stabilizes the time-crystalline order, preventing the system from heating to a featureless infinite-temperature state.

Published as arXiv:2501.15673, this work positions Floquet time crystals as more than a curiosity. They're becoming a benchmark for quantum processor performance and a testbed for understanding how quantum systems interact with their environments.

Aalto University: A Time Crystal That Lasts 10 Seconds

Meanwhile, at Aalto University in Finland, Autti, Heikkinen, Mäkinen, Volovik, Zavjalov, and Eltsov achieved something arguably even more impressive in a very different system. Working with superfluid helium-3 — one of the most exotic quantum fluids known — they observed a discrete Floquet time crystal with a lifetime exceeding 10 seconds.

Ten seconds may not sound long in human terms, but in the quantum world it's an eternity. The previous record for time crystal lifetimes was roughly 100 milliseconds. This represents a hundred-fold improvement — the kind of leap that transforms a phenomenon from "we can barely see it" to "we can work with it."

Published in Physical Review Letters (134, 076301), this result suggests that time crystals in the right medium can achieve the kind of stability needed for practical applications in precision sensing and timekeeping.

The Big Picture: What 2025 Means for Floquet Engineering

Taken individually, each of these results is a significant advance. Taken together, they represent a phase transition in the field itself — from theoretical possibility to experimental reality. Here's what the landscape looks like now:

• Floquet topological insulators have been observed in real solid-state materials, with topological gaps large enough to be technologically relevant (40–50 meV)
• Topological switching has been demonstrated at sub-picosecond speeds in a commercially available material (black phosphorus)
• Light-induced superconductivity has been pushed to 5× the equilibrium critical temperature, suggesting a systematic route to higher-Tc states
• Floquet time crystals have achieved both digital stability (1,000+ cycles on quantum hardware) and analog longevity (10+ seconds in superfluid ³He)

"We are no longer asking whether Floquet engineering works in real materials. We are asking how far it can go — and how quickly we can turn these phenomena into technologies."

What Comes Next

The immediate challenges are clear. All of the Floquet states observed so far are transient — they exist only while the system is being driven, and they dissipate once the drive is turned off. Making Floquet-engineered phases persistent, or at least long-lived enough for practical use, is the central engineering challenge of the next decade.

Several promising directions are already being explored:

• Continuous-wave driving: Replacing pulsed lasers with continuous drives could maintain Floquet states indefinitely, though managing heat dissipation remains a challenge
• Cavity integration: Placing materials inside optical cavities could reduce the required driving power by orders of magnitude while maintaining the Floquet-engineered band structure
• Hybrid approaches: Combining Floquet driving with static material design — starting with a material that's "almost" topological or "almost" superconducting and using the drive to push it over the edge
• Dissipation engineering: As Google's time crystal experiment showed, carefully controlled dissipation can stabilize rather than destroy Floquet phases

The energy implications are particularly exciting. If Floquet-enhanced superconductivity can be made persistent and extended to ambient conditions, it would revolutionize power transmission, energy storage, and quantum computing. If Floquet topological switches can be integrated into circuits, they could enable a new generation of ultrafast, fault-tolerant electronics. And if time crystals can serve as quantum memories or precision sensors, they could underpin entirely new measurement technologies.

2025 didn't just produce a handful of impressive experiments. It established Floquet engineering as a practical tool for creating new states of matter — and it opened the door to a future where the properties of materials are not fixed by chemistry, but programmable with light.