Breaking the tiny bounds of quantum mechanics, researchers at the Southern University of Science and Technology and the Quantum Science Center of the Guangdong–Hong Kong–Macao Greater Bay Area have created a massive Schrödinger cat particle under ultracold conditions, reaching nearly absolute zero.

In quantum mechanics, particles can exist in a superposition of uncertainty, only existing in a certain position once they are measured, most famously illustrated by Schrödinger’s cat, an example in which the condition of a cat inside a box cannot be known until opening it.

Now, in a recent paper published in Nature Physics, the team revealed how they developed a seven-atom cluster that, when passing through a barrier higher than its own kinetic energy, entered a superposition state on a new scale.

Quantum Superposition

When an object enters a quantum superposition, it theoretically occupies multiple points of space at once, with its precise location unsure until measurement occurs. Typically, this is relegated to extremely tiny sub-atomic systems. Yet in their new research, the Hong Kong and Chinese team produced quantum tunneling in a larger system, which could be a major boon to the development of quantum sensors at a larger scale.

In addition to spatial quantum superposition, the team identified quantum tunneling as the other core concept in their recent work. A particle’s ability to quantum tunnel, which references its ability to cross a solid or energy barrier that would typically be impenetrable based on classical physics, declines with mass.

The researchers wondered whether there was a way around this, allowing macroscopic objects to undergo quantum tunneling. Typically, quantum tunneling occurs at the subatomic scale, perhaps a single atom at most, yet the team sought to move several atoms joined together through a quantum tunnel in their new work. 

Quantum Activity at Large Scale

For their large-scale quantum tunneler, the team built a mass system on an optical lattice by cooling the atoms to near absolute zero and trapping them with laser beams. Many quantum technologies, such as quantum computers, require extremely low temperatures, as cooling atoms to this degree enhances their quantum properties.

While the added mass complicates quantum tunneling due to inefficiency, creating a superposition in such a relatively large object could have fascinating repercussions for fundamental physics, especially in the poorly understood relationship of quantum mechanics and gravity.

The key to the team’s success was using a relatively weak bond between atoms rather than the tighter bonds typically used, allowing them to exploit the object to achieve a tunneling strength closer to that of a single atom.

With this new method, the team has developed a highly scalable process that is theoretically capable of achieving the same results with about 100 atoms. Further work to confirm their results could lead to the generation and detection of even larger spatial quantum superpositions.

Future Applications

The work may enable future researchers to investigate quantum effects at even larger scales and facilitate the development of quantum sensors and measurement devices. Additionally, atomic interferometry, which measures motion, gravity, time, and more based on the atom’s wave-like behaviors, could benefit from the technique by pushing it past the normal quantum limit.

This could be especially useful in investigating the weak relationship between gravity and mass, which is hard to detect at very small scales.

In the near future, the researchers have identified specific elements of their work that they will continue to pursue. Their success with the experiment also enabled the team to observe peculiar quantum phenomena, such as long-lived, strongly interacting states and many-body interactions, which they hope to investigate further.

Moving forward, they also aim to push beyond the current theoretical limit of 100 atoms in their work to several hundred atoms.

The paper, “Scalable Generation of Massive Schrödinger Cat States Via Quantum Tunnelling,” appeared in Nature Physics on May 11, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.

The strange quantum nature of time moves one step closer to being untangled, thanks to new research on optical ion clocks that could allow scientists to test the flow of time in a new way.

Since Albert Einstein first presented his theory of relativity, scientists have known that the flow of time is not absolute. Yet quantum theory takes this further, suggesting that time may exist in a superposition, flowing both slower and faster concurrently, not being set until it is measured.

Now, a research team from the Stevens Institute of Technology, Colorado State University, and the National Institute of Standards and Technology (NIST) has published a paper in Physical Review Letters describing how optical ion clocks could be used to evaluate whether time itself can exist in a quantum superposition.

Atomic Clocks and Quantum Time

In an atomic clock, the device is tuned to the steady vibration of an atom, which acts as a natural metronome, keeping time with extraordinary precision. Thanks to their stability and accuracy, atomic clocks underpin GPS and global communications systems, ensuring that everything is precisely synchronized. Now, researchers are exploring how that same precision might be applied at the quantum level.

These clocks rely on motion—the vibration of an atom. Yet in quantum theory, motion itself can exist in a superposition, remaining uncertain until it is measured. This makes atomic clocks a promising tool for investigating whether the same uncertainty applies to the flow of time.

“Time plays very different roles in quantum theory and in relativity,” said co-author Igor Pikovski, Assistant Professor of theoretical physics at Stevens Institute of Technology. “What we show is that bringing these two concepts together can reveal hidden quantum signatures of time-flow that can no longer be described by classical physics.”

Quantum Relativity

Relativity shows that time is not absolute or independent, but instead depends on the clock measuring it. Velocity and position are key factors that determine how quickly time passes relative to a given observer. For example, a clock moving at a different speed will experience time differently—a phenomenon confirmed by atomic clock experiments.

This idea is often illustrated by the twin paradox: if one identical twin travels at high speed while the other remains on Earth, they will age at different rates. In quantum theory, however, this concept gives rise to the so-called quantum twin paradox, in which a single system can experience multiple timelines simultaneously in a superposition. While this idea is theoretically sound, experimental tests have remained out of reach with current technology.

Atomic Clocks and Relativity

In their new research, the team demonstrated that combining advanced atomic clock technology with quantum computing techniques could enable quantum time research. 

“Atomic clocks are now so sensitive, they can detect tiny differences in time caused by just the thermal vibrations at minuscule temperatures,” said co-author Gabriel Sorci, a PhD candidate at Stevens Institute of Technology. “But even at the absolute zero temperature, the ground state, the ticking rate will still be affected by just the quantum fluctuations alone.”

The researchers showed that cooling techniques used in quantum computing can produce so-called squeezed states, where quantum behavior becomes detectable within the clock. In theory, this could allow a single clock to measure time as both faster and slower simultaneously.

“Physics is still full of mysteries at the most fundamental level,” Pikovski concluded, adding that “Quantum technologies are now giving us new tools to shed light on them.”

The paper, “Quantum Signatures of Proper Time in Optical Ion Clocks,” appeared in Physical Review Letters on April 20, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.