Quantum-Scale Schrödinger Cat: Protein-Size Superposition and US Science Funding Under Trump

In this episode, researchers push quantum superposition to the scale of protein-sized objects using a three-laser matter-wave interferometer to observe interference in sodium clusters 5–8 nm in diameter, a mass range comparable to large proteins and small viruses. The show also examines the first year of Donald Trump’s second presidency and its impact on US science funding, from thousands of grants being terminated or frozen to a tightened budget climate and rising political influence over grantmaking and immigration policies that affect researchers and international students.

Protein-scale quantum superposition

In this segment, researchers push quantum superposition to the scale of protein-sized objects by using sodium clusters (5 to 8 nanometers) in a center-of-mass superposition, separated by about 100 nanometers, and observed through a matter-wave interferometer formed by lasers. The interference fringes at the end of the apparatus indicate the particles behave as waves rather than classical particles, showing a mass scale close to large proteins and even small viruses. The macroscopicity metric places this work roughly an order of magnitude beyond earlier experiments, reflecting progress in mass, separation, and coherence time.

"the center of mass of these 5 to 8 nanometer nanoparticles is separated by about 100 nanometers and it is at both here and there at the same time" - Sebastian Petolino

Interpreting Schrödinger's cat at the nanoscale

Lizzie Gibney speaks with Petolino about the aim: whether quantum mechanics that governs light and atoms extends to larger objects, or if a new regime yields classical behavior. In the experiment the metal sodium clusters are prepared in a center-of-mass superposition, and the wave nature becomes evident only when interference fringes appear after the interferometer passes the particles through three laser gratings. Before fringes, the signal was flat, a sign that quantum effects could be masked by misalignment, laser power, or vacuum quality. A flat line is not conclusive evidence; fringes demonstrate the quantum phenomenon.

"before we had those interference fringes, it was basically just flat lines" - Lizzie Gibney

Macroscopicity and the road ahead

The discussion moves to how this work compares with other groups pursuing larger masses, different setups, or longer coherence times. The team uses a macroscopicity measure to combine mass, separation, and coherence time; the current result advances the macroscopicity by about an order of magnitude to 15.5. While other experiments claim higher masses or bigger separations, they trade off other parameters. The trio notes that a real achievement is integrating these aspects within a single interferometer and moving toward applying this tool to learn about the molecules or biological objects passing through the device. Petolino also envisions future work with genuinely large biological objects and the potential to tune fringe shifts with external fields to probe molecular properties.

"it's not so far out of reach anymore" - Sebastian Petolino

US science funding under Trump: a year in review

The program shifts to policy and funding, with Max Kozlov guiding a retrospective of the US science funding landscape under the Trump administration. The analysis highlights that about 8000 research grants were terminated or frozen in the year, a number the NIH and NSF found unprecedented. Courts reinstated roughly half, but many researchers could not revive funding within a budget period, leaving projects idle and potentially derailed. Overall, about $1.4 billion in funding was lost for projects not reinstated. The NSF and NIH issued roughly 25% fewer new grants in 2025 relative to the past decade due to a budgeting approach that front-loads large awards, creating a tighter funding climate and more intense competition. International researchers faced uncertainty and a notable drop in international students, with a 17% year-over-year decline attributed to policy changes and immigration restrictions.

"the politicization of science has been kind of cranked up to a maximum this past year" - Max Kozlov

Looking ahead: watchpoints for the coming year

The discussion closes with a look to 2026: NIH institute directors are in flux, peer-review scores may be weighed against agency priorities, and geographic considerations could play a bigger role in funding decisions. The team emphasizes that while biological objects pose challenges for interferometry, progress continues and new ideas, like Schrödinger's amoeba, appear more plausible with time. The conversation leaves listeners with a sense of ongoing progress and the potential for broader applications of interferometry in biology and materials science.

"not so far out of reach anymore" - Sebastian Petolino

Closing notes

Show notes provide links and context for further reading, with a prompt to follow the podcast on social media for updates and future episodes.