By linking two atomic clocks using the phenomenon of quantum entanglement, Oxford researchers have paved the way for significant progress in fundamental physics.

Researchers affiliated with the University of Oxford have managed to put two atomic clocks into a state of quantum entanglement, all at a distance of nearly two meters. It’s the first time this phenomenon has been confirmed experimentally at this distance, and this startling new record could have profound implications for research, especially in relation to mysterious dark matter.

To understand the ins and outs of this feat on a quantum scale, we must first look at the particularities of atomic clocks. It’s a concept born in the 1950s, with the aim of offering an exceptionally precise method of recording time.

## Even atomic clocks have their limits

And this is not an exaggeration. Standard quartz watches typically exhibit a deviation of the order of a second every few days. In atomic clocks, on the other hand, this deviation is of the order of**one second… every 100 million years.**

To achieve this incredible degree of precision, there is no question of using a quartz crystal and gears. Instead, atomic clocks rely on the extremely precise periodicity of certain phenomena that take place on the scale of the atom, within the framework of nuclear reactions. For example, the cesium-133 atom oscillates exactly 9,192,631,770 times per second; this measure has been used as the official definition of the second since 1967.

Suffice to say that this instrument has already radically changed the face of our civilization. The time provided by an atomic clock is today the basis of all modern communication and navigation systems. The same is true for scientific research, particularly in fundamental physics; without this ability to measure time very precisely, humanity would have been deprived of many very important discoveries.

## Synchronization based on quantum entanglement

But even these incredibly regular and stable atomic phenomena are not perfect. Atomic clocks also exhibit some degree of inaccuracy, albeit ridiculously small. Obviously, some researchers have taken it into their heads to push this already phenomenal level of precision even further. And as often in physics, this race for precision has pushed specialists to venture into the strange world of quantum physics.

In particular, they explored the potential interest of a mysterious phenomenon, quantum entanglement. Very briefly, it is a quantum state where two particles are linked by an inextricable link independent of their distance, so much so that they can no longer even be described independently of each other.

Technically, if one of the two particles undergoes the slightest modification, the other member of the tandem will undergo precisely the same effects, even if it is located at the other end of the universe. This notion gave rise to a famous phrase by Albert Einstein, who referred to quantum entanglement as a “frightening action at a distance”.

## Two entangled atomic clocks two meters apart

Researchers have therefore asked themselves a question which, at first glance, might seem absurd; would it be possible to use quantum entanglement to improve the precision of atomic clocks? And unexpectedly, the answer turned out to be a resounding “yes”.

Several teams of physicists have shown that it is possible to integrate two atomic clocks in the same system, then to “synchronize” them by forcing certain particles to pass into a state of quantum entanglement. On paper, this approach achieves an even greater level of precision than a normal atomic clock.

This was already an interesting advance in theory; but Oxford researchers have just taken this field of research into a whole new dimension. In their work published on September 8, they showed that it was possible to play on quantum entanglement to link two atomic clocks in distinct and even physically separate systems!

In practice, therefore, they have created the very first quantum network in good and due form. Admittedly, this is only a proof of concept for the moment. Their testing has yet to achieve revolutionary levels of accuracy. But that was not the goal of the researchers in this specific case; and the implications of this work are nonetheless particularly profound.

## Deep Implications for Fundamental Physics

And for good reason: by exploiting this phenomenon at a distance of the order of a metre, the Oxford researchers have reached a stage where we can **begin to consider practical and concrete applications** for this technology, which was simply unthinkable for experiments that worked at the nanometer scale.

This paves the way for the construction of **large-scale arrays of perfectly synchronized atomic clocks** ; once this technology matures, it will quantify the passage of time with startling precision, far beyond the best atomic clocks today.

This study could therefore serve as the basis for a whole host of other work which will themselves lead to revolutionary discoveries. For example, North American researchers have already suggested that a system of this type – still hypothetical at the time – could help physicists in their** dark matter tracking**. We can also imagine applications in the context of quantum computing, for example.

And that’s just the tip of a huge iceberg of possibilities. More broadly, this work paves the way for **great ** **progress in quantum physics,** with all that this implies for our overall understanding of the universe. It will therefore be necessary to follow the results of this work with particular attention.