They got about 15 trillion atoms to share the space in a chamber of gas set at untypical temperatures, which sets a new record. Entangled states are incredibly fragile as in most cases, even a tiny commotion can undo the entanglement.
For those unfamiliar with the theory, quantum entanglement is the phenomenon at the core of quantum physics, where two particles can affect each other, irrelevant to the distance between them. Therefore, measuring one of them offers scientists the measurement of the other right away.
Setting a New Record
Although researchers do not completely understand why this event takes place, it does happen. However, demonstrating quantum entanglement is still a sensitive and challenging process. Entangled conditions require very specific settings in order to exist and survive, with the majority of the experiments in this field of research being performed at temperatures reaching absolute zero.
And this is why the new study is such a successful attempt. The physicists were able to design a hot, chaotic gas of atoms heated to approximately 450 Kelvin (177 degrees Celsius or 350 degrees Fahrenheit), filled with around 15 trillion entangled atoms, which is about 100 times more than have ever been analyzed before.
These atoms were not isolated as calculations made by lasers depicted them crashing into each other, and there were, at times, thousands of other atoms between entangled couples. The analysis also showed the state of entanglement might be more powerful than earlier thought.
“If we stop the measurement, the entanglement remains for about one millisecond, which means that 1,000 times per second, a new batch of 15 trillion atoms is being entangled,” says quantum physicist Jia Kong from the Institute of Photonic Sciences in Spain (ICFO).
“You must think that 1 ms is a very long time for the atoms, long enough for about 50 random collisions to occur. This clearly shows that the entanglement is not destroyed by these random events. This is maybe the most surprising result of the work.”
Although most quantum entanglement experiments utilize ultra-low temperatures to maintain the interference like these clashes to a minimum, this research that used rubidium metal and nitrogen gas, shows that entanglement can thrive in much hotter conditions.
Using the Method in Brain Imaging
If this event would be usable in the next-generation of communication systems and quantum computers, we have to get it functioning in warmer, noisier settings, and that is something this new study paves the way towards.
One of the ways these discoveries could be helpful in the future is in magnetoencephalography or magnetic brain imaging, a technique that employs similar hot, high-density atomic gases to identify magnetic fields generated by brain activity. Entanglement could then make the method more delicate. However, for now, physicists have understood more about the laws of quantum entanglement, and what it can and cannot resist.
“This result is surprising, a real departure from what everyone expects of entanglement,” says ICFO quantum physicist Morgan Mitchell. “We hope that this kind of giant entangled state will lead to better sensor performance in applications ranging from brain imaging to self-driving cars, to searches for dark matter.”
The research has been published in the journal Nature Communications.