Researchers at New York University have successfully engineered a novel manifestation of an exotic state of matter, wherein particles are suspended via acoustic forces and engage in mutual interactions through the transmission of sound waves.
Morrell and colleagues documented a novel variant of a time crystal, characterized by particles that levitate on an acoustic platform and interact by exchanging sonic energy.
Time crystals, defined as collections of particles exhibiting periodic temporal behavior, present substantial potential for advancements in quantum computation, data storage, and various other applications.
The particles within this newly developed time crystal deviate from the principles of Newton’s third law of motion, which posits that for every action, an equal and opposite reaction ensues, implying forces consistently manifest in balanced pairs (i.e., possessing identical magnitude and opposing direction).
In contrast, these particles exhibit a more independent mode of interaction, not inherently bound by balanced force dynamics—they operate on a nonreciprocal basis.
Remarkably, these observable time crystals, discernible to the unaided eye, are suspended by a compact, handheld apparatus approximately one foot in height.
“The integrated speakers generate acoustic waves, enabling us to position minute particles within the pressure antinodes of these waves, where they are levitated against the force of gravity,” explained Leela Elliott, an undergraduate student at New York University.
The team’s time crystal comprises polystyrene beads held aloft by sound waves, which function as an ‘acoustic levitation system’ to initially maintain the beads in a stationary state mid-air.
“We have ascertained that a remarkably straightforward system involving two particles, levitated within an acoustic standing wave, can achieve spontaneous oscillatory behavior and exhibit a time crystal phenomenon through their unbalanced interactions,” stated Mia Morrell, a graduate student at New York University.
“Crucially, when these levitated particles engaged with one another, their interaction occurred via the exchange of scattered sound waves.”
“More precisely, larger particles exhibit a greater capacity to scatter sound compared to smaller particles.”
“Consequently, a larger particle exerts a more significant influence on a smaller particle than the smaller particle does on the larger one.”
“The resultant interaction between a small and a large particle is therefore asymmetric.”
“Visualize two vessels of disparate sizes approaching a harbor.”
“Each vessel generates water waves that impinge upon the other, thereby imparting a push—yet the magnitude of this push varies proportionally to their respective sizes.”
These findings serve to broaden the horizon of possibilities that these crystals offer to technological and industrial sectors.
“Time crystals demonstrate a considerably higher degree of autonomy, as they self-determine all parameters and maintain their operational status,” commented Professor David Grier of New York University.
“They are captivating not only due to their inherent potential but also because they appear exceptionally exotic and intricate.”
“Our experimental setup, by comparison, is noteworthy for its exceptional simplicity.”
The published research can be found in the esteemed journal Physical Review Letters.
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Mia C. Morrell et al. 2026. Nonreciprocal Wave-Mediated Interactions Power a Classical Time Crystal. Phys. Rev. Lett 136, 057201; doi: 10.1103/zjzk-t81n
