Physicists Harness Quantum Time Reversal to Detect Dark Matter and Gravitational Waves

MIT Researchers Used A System Of Lasers To First Entangle, Then Reverse The Evolution Of A Cloud Of Ultracold Atoms.

MIT Researchers Used A System Of Lasers To First Entangle, Then Reverse The Evolution Of A Cloud Of Ultracold Atoms.

Digital Visualization Art of an Atom
Digital Visualization Art of an Atom (Image: Unsplash)

It is hypothesized that quantum vibrations in atoms hold a whole world worth of information. If the scientists somehow can make something that is able to measure these vibrations accurately, their atomic oscillations, plus their evolution over time, they can hone the atomic clocks which are systems of atoms whose fluctuations can indicate the presence of dark matter, a passing gravitational wave, or even new, unexpected phenomena.

Limitations to the Procedure

One of the biggest hurdles in measuring these vibrations is the noise from the classical world, which if not kept in check can overwhelm these already hard to detect vibrations, thus contributing to the increasing difficulty.


MIT scientists have found a way which would significantly amplify quantum changes in atomic vibrations, by putting the particles through two key processes: quantum entanglement and time reversal. Although the men at MIT haven’t found a way to reverse time itself however, they have manipulated quantumly entangled atoms in a way that the particles behaved as if they were evolving backward in time. Furthermore, these changes in the atomic oscillations are amplified, so that they could easily be measured.

The Technique

To amplify and measure the amplified atomic vibrations that fluctuate within the quantum realm, MIT scientists developed SATIN (for signal amplification through time reversal). The technique could improve the accuracy of current state-of-the-art atomic clocks by a factor of 15, making their timing so precise that over the entire age of the universe the clocks would be less than 20 milliseconds off.

A System of Lasers to Reverse the Evolution of Atoms

Additionally, there is one more application of this technique that is to further focus quantum sensors that are designed to detect gravitational waves, dark matter, and other physical phenomena.

The Lester Wolfe Professor of Physics at MIT says; “We think this is the paradigm of the future, any quantum interference that works with many atoms can profit from this technique”.

Application of the New Technique

To surpass the Standard Time Limit in atoms, scientists at MIT, instead of trying to improve the resolution of existing readout tools, the team looked to boost the signal from any change in oscillations, such that they could be read by current tools. They did so by harnessing another curious phenomenon in quantum mechanics i.e., time reversal.

This new method would isolate the atoms from the classical noise which would make these atoms evolve forward in time in a predictable manner, and the atoms’ interactions (such as their oscillations) should be described precisely by the system’s “Hamiltonian”, essentially a mathematical description of the system’s total energy.

Professor Vladan Vuletić said; “A cloud of dark matter floating by Earth could change time locally, and what some people do is compare clocks, say, in Australia with others in Europe and the U.S. to see if they can spot sudden changes in how time passes,” Vuletic says. “Our technique is exactly suited to that, because you have to measure quickly changing time variations as the cloud flies by.”

by Talha Shaikhani