In a groundbreaking advancement bridging the realms of quantum mechanics and nanoscale physics, researchers at the University of Tokyo have successfully demonstrated quantum squeezing of a levitated nanomechanical oscillator. This achievement, led by Mitsuyoshi Kamba, Naoki Hara, and Kiyotaka Aikawa, reveals the ability to reduce the uncertainty in the motion of a nanoscale particle to levels surpassing the quantum mechanical zero-point fluctuations. Published in the prestigious journal Science, their work opens new frontiers for precision measurement and quantum technology applications, including autonomous vehicle navigation and sensor development impervious to conventional limitations.
Quantum mechanics, the fundamental theory governing the behavior of particles at the atomic and subatomic scales, is often regarded as counterintuitive when compared to classical physics. One of its defining characteristics is the inherent uncertainty principle, which sets a fundamental limit on the precision with which certain pairs of physical properties, such as position and momentum, can be simultaneously known. For particles trapped and cooled near their lowest quantum state, these uncertainties are manifested as zero-point fluctuations. The innovative concept of quantum squeezing aims to engineer states where uncertainties in one observable, such as velocity or position, are reduced below this zero-point limit at the expense of increased uncertainty in the conjugate variable, enhancing measurement precision beyond classical constraints.
Historically, the application of quantum mechanical principles to microscopic entities like photons and atoms has been a cornerstone of modern physics and technology. However, extending these principles to macroscopic or nanoscale objects poses significant challenges. Larger particles traditionally exhibit classical behavior due to interactions with their environments, which cause decoherence and mask quantum effects. Dr. Kiyotaka Aikawa and his team sought to overcome these challenges by isolating a nanoscale glass particle in a highly controlled optical and vacuum environment, effectively creating a suspended system akin to what is known as a levitated optomechanical oscillator.
Their experimental setup involved trapping a single glass nanoparticle within an optical potential formed by a tightly focused laser beam. This optical levitation allows the particle to be suspended stably in a vacuum, minimizing mechanical contact and environmental disturbances that would otherwise introduce noise and disrupt quantum behavior. By carefully cooling the nanoparticle’s motional degrees of freedom close to its quantum ground state through feedback and passive cooling techniques, the team effectively prepared its mechanical motion at the threshold where quantum effects become measurable.
Central to their methodology was the precise modulation of the trapping potential, which enabled them to manipulate the nanoparticle’s state; this involved releasing and recapturing the particle at carefully timed intervals. By measuring the scattered light from the nanoparticle’s motion, they could infer its center-of-mass velocity distribution immediately before the particle was allowed to “fly” or move freely for a brief period. Repeated measurements allowed them to statistically analyze the velocity distribution and detect deviations indicative of quantum squeezing.
Remarkably, the researchers observed a velocity uncertainty narrower than that of the particle’s zero-point motion, a clear signature of a squeezed state. This observation represents a milestone because it demonstrates that even nanoscale mechanical objects—substantially larger than atoms—can exist temporarily in quantum states with enhanced measurement precision. Quantum squeezing in such mesoscopic systems bridges the divide between microscopic quantum particles and macroscopic classical systems and sets the stage for novel quantum devices that leverage both scales’ unique advantages.
However, achieving this milestone was fraught with technical complexities. Environmental vibrations, laser intensity fluctuations, and residual gas collisions in the vacuum chamber introduced noise that could mask the delicate quantum properties of the nanoparticle. Overcoming these obstacles required innovations in laser stabilization, ultra-high vacuum techniques, and signal detection sensitive enough to distinguish quantum signatures from background noise.
The levitation technique itself presented fundamental challenges. Maintaining a stable optical trap that does not induce excess heating or perturb the particle’s quantum state demands exquisite control over laser parameters and mechanical feedback systems. The team’s success in balancing these factors demonstrates not only experimental prowess but also opens new paths to exploring quantum mechanics’ foundations at unprecedented scales.
From a fundamental physics perspective, this work allows scientists to probe the boundary where quantum mechanics transitions into classical behavior—a long-standing question in modern physics. Examining quantum squeezing in levitated nanoparticles sheds light on decoherence processes and the limits of quantum theory when applied to objects visible to the naked eye or practical technologies.
Practically, the implications extend far beyond academic curiosity. Sensors that operate near quantum limits of measurement could drastically improve navigation systems, especially in GPS-denied environments such as underground or underwater locations. Autonomous systems relying on precise inertial measurements would benefit from such squeezed states, enhancing safety and operational reliability. Furthermore, quantum squeezing could enhance signal-to-noise ratios across a variety of sensor platforms, from gravitational wave detection to biomedical imaging.
Dr. Aikawa notes the surprising sensitivity of levitated nanoparticles to environmental fluctuations—a double-edged sword that poses both challenges and opportunities. While this sensitivity necessitates stringent isolation methods, it also promises an ultra-responsive platform for measuring minute forces and fields at scales previously inaccessible.
Looking ahead, the research team envisions expanding these techniques to improve quantum control over larger and more complex mechanical systems. Such advancements could underpin the development of next-generation quantum technologies, including quantum communication devices, memory systems, and sensors with performance bounds dictated by fundamental quantum limits rather than classical noise.
This breakthrough represents a significant step on the roadmap toward a richer understanding of quantum mechanics’ applicability in the mesoscopic world and its technological exploitation. As the boundary between classical and quantum realms continues to be explored with innovative experiments like this, the potential for transformative applications in science and industry grows exponentially.
The demonstration of quantum squeezing in an optically levitated nanomechanical oscillator highlights the power of integrating optical trapping, ultra-cold physics, and quantum measurement techniques. By controlling and measuring mechanical motion with quantum-limited precision, the team has laid foundational groundwork whose influence will resonate across fields as diverse as fundamental physics, quantum information science, and applied engineering.
Subject of Research: Quantum squeezing in levitated nanomechanical oscillators
Article Title: Quantum squeezing of a levitated nanomechanical oscillator
News Publication Date: 18-Sep-2025
Web References: 10.1126/science.ady4652
Image Credits: Kamba et al. 2025
Keywords
Quantum squeezing, levitated nanoparticles, nanomechanical oscillators, zero-point fluctuation, optical levitation, quantum measurement, nanoscale physics, quantum-classical boundary, precision sensors, vacuum cooling, optomechanics, quantum uncertainty
