Quantum mechanics might seem completely far removed from our day-to-day life but its properties are used in plenty of devices we commonly use. Even its most outlandish phenomena might soon become part of familiar technology.
This could be the case for new research that has achieved quantum entanglement in a hot and messy system of 15 trillion atoms, that's 100 times more than the previous record. The researchers believe that having such an entangled state could be used to detect extremely faint magnetic signals in the brain, improving scans of what’s happening inside our heads. The breakthrough is published in Nature Communication.
Quantum entanglement is a unique quantum phenomenon that has no comparable analogy in classical physics. Entanglement is the physical phenomenon that occurs when you have particles in pairs or groups sharing the same space in a way that means you can not distinguish them independently but have to take them as a single quantum state. Even if they are far apart you have to consider them as a whole rather than individual elements, and the most curious thing is that measuring one will influence the other. Instantaneously. Even if they were on the other side of the universe.
Entanglement has been proven correct in experiments time and time again, but it is a fragile state so researchers have to take good care in creating a system of just a few atoms at very low temperatures, close to absolute zero, to not disturb it. However, if you want to look at only some of the properties of entanglement, like the researchers here, you can certainly get more creative.
They focused on vaporized rubidium heated to 177°C (350°F) where the atoms were not at all isolated but bouncing off each other. Despite the chaotic system, the researchers found an enormous number of entangled atoms – almost one-third of all the atoms in the gas, about 100 times more than has ever been seen before. They also found the entanglement was "non-local", meaning between two entangled atoms, there were thousands of others, in a big, hot mess of an entangled state.
That wasn't the most surprising element, though. The entanglement would break in a fraction of a second but then new entanglements would form.
“If we stop the measurement, the entanglement remains for about 1 millisecond, which means that 1,000 times per second a new batch of 15 trillion atoms is being entangled,” lead author Jia Kong, from ICFO, Barcelona, explained in a statement. “And you must think that 1 millisecond 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”.
Atoms can act as little magnets, and the entanglement enhances these "sensing" capabilities. A quantum entangled system could be used to detect faint magnetic fields like those produced in the brain. The ultra-cool setup for most quantum entanglement experiments are not ideal for biological-orientated sensors, but something like this could well end up in new applications in fundamental brain science and neurosurgery.
“This result is surprising, a real departure from what everyone expects of entanglement,” senior author Professor Morgan Mitchell said. “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.”