That view shifted in 2024 when Igor Pikovski, assistant professor at Stevens Institute of Technology, and collaborators reported work in Nature Communications showing that graviton detection is possible using modern quantum technologies. In their analysis, they demonstrated that previous no go arguments fail once advances in quantum control and measurement of macroscopic systems are taken into account, reframing graviton detection as an experimental challenge rather than an absolute impossibility.
The new approach combines two major experimental breakthroughs. The first is the direct observation of gravitational waves, the ripples in space time produced by collisions of black holes or neutron stars that Einstein predicted more than a century ago and which were first observed in 2015. In a quantum picture, these classical looking waves can be viewed as large ensembles of gravitons acting collectively, so conventional detectors see only their macroscopic effect, not the individual quanta.
The second breakthrough arises from quantum engineering of massive systems. Over the past decade, researchers have learned to cool, control and read out increasingly heavy objects in genuine quantum states, extending quantum behavior far beyond atoms and molecules. In 2022, Jack Harris and his team at Yale University reported a landmark experiment in which they controlled and measured individual vibrational quanta of superfluid helium with a mass exceeding a nanogram, showing that macroscopic quantum motion can be resolved one quantum at a time.
Pikovski recognized that combining gravitational wave sources with such macroscopic quantum sensors opens a pathway to single graviton detection. In this scheme, a passing gravitational wave can transfer exactly one quantum of energy one graviton into a large, ultra sensitive quantum system, producing a tiny but measurable shift in its vibrational energy. The main obstacle is that gravitons interact extremely weakly with matter, but theory indicates that gram to kilogram scale quantum systems exposed to intense waves from merging black holes or neutron stars could absorb individual gravitons at detectable rates.
Building on these theoretical insights, Pikovski and Harris have launched a first of its kind experimental program explicitly aimed at detecting individual gravitons. Supported by the W. M. Keck Foundation, they are developing a centimeter scale superfluid helium resonator engineered to approach the regime where single gravitons from astrophysical gravitational waves can be absorbed and converted into measurable mechanical excitations. This work moves graviton detection from an abstract concept toward a concrete laboratory platform.
The experimental design centers on a gram scale cylindrical resonator immersed in superfluid helium and cooled to its quantum ground state so that even a single added vibrational quantum can be resolved. Laser based measurements probe the resonator to detect individual phonons, the discrete vibrational quanta into which absorbed gravitons would be converted. The detector extends systems already operating in the Harris laboratory, but pushes them into a new regime by scaling the mass to the gram level while preserving the extremely high quantum sensitivity needed to see single quanta.
Successfully operating this platform will provide a blueprint for future detectors capable of reaching full graviton sensitivity. The team expects that once the gram scale device is demonstrated, subsequent generations can be scaled up and optimized to match the signal strengths from strong astrophysical gravitational wave sources. Such progress would open an experimental window on quantum gravity, enabling direct tests of how spacetime behaves at the most fundamental level.
Pikovski notes that the history of quantum physics began with carefully designed experiments on light and matter that revealed photons and other quanta. The new graviton detector project seeks to bring gravity into this same experimental domain, targeting gravitons with the same level of precision that early twentieth century physicists brought to photons. If successful, the effort could transform quantum gravity from a largely theoretical endeavor into a data driven science anchored in laboratory observations.
Related Links
Stevens Institute of Technology
The Physics of Time and Space
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