Physicists Discovered a New Form of Quantum Entanglement
The spooky action at a distance just got even spookier
Hiya!
Something is happening. Have you felt it? I’ve been sensing it for a few years now. It’s almost as though we’re going through some subtle yet revolutionary transition, many transitions, in fact. Socially, politically, morally, and even technologically. I’m in my mid-thirties and gave up long ago trying to keep up with the new gadgets and gizmos coming out every year.
But in the background of the louder shifts occurring, science is also having a moment. I mean, I’m learning about new scientific breakthroughs left and right! I can barely keep up with them. I’m learning so much I actually took a break from writing about physics to allow my brain to solidify again. Now I find out a new type of quantum entanglement was discovered during my break—pure insanity. So naturally, I have to tell you about it.
What is Quantum Entanglement?
First, we should probably revisit what quantum entanglement is. This way, we can better understand the physicists’ exciting discovery. At the very least, I’m sure you know that Albert Einstein called quantum entanglement “spooky action at a distance.”
You likely also know that entanglement involves an elusive connection between at least two particles resulting in them behaving as one, regardless of the distance between them. The exact moment one particle changes in any way, its entangled partners do too.
But how does entanglement happen in the first place? Actually, why does it happen at all? Those are tricky questions to answer, and in fact, we don’t really have the answers. Though, experts have made some headway with the former. They at least know enough to create entangled particles in a lab.
Traditionally, physicists create entangled particles by sending a single particle, let’s say a photon (light particle), through what’s known as a down-conversion crystal and having two photons come out. The two photons that emerged from the crystal are no different than any other photon in that they have a regular spin, lack an electric charge, possess wavelengths defined by their energy, and all the other standard quantum behaviors expected of a photon particle.
Except the particles are entangled, so they also have properties that connect them in a way our current understanding of quantum physics can’t explain.
For the sake of simplicity, examples of entanglement usually use photons and only use two particles or paired photons. But according to Caltech Science Exchange, entanglement can occur among “hundreds to millions or more particles.” Further, it’s thought to occur “throughout nature, among the atoms and molecules in living species and within metals and other materials.” This suggests quantum entanglement is far more common than I think many of us realized. At least, I didn’t know.
Until recently, scientists thought the only way to create entangled particles was by conducting experiments using particles identical in nature, which means the same types of particles — a photon entangled with another photon. But now, physics has discovered, for the very first time, that quantum entanglement can occur between fundamentally different particles. The particles don’t even have to have the same electric charges.
New Quantum Entanglement
Hold on to your seat, or maybe go top off your coffee before we dive into this next bit. It’s a little confusing if you’re not a physicist but don’t worry. I’ll walk you through it.
Let’s start with the particles involved in the discovery, called mesons, which are some of the easiest particles for physicists to produce. Mesons form from collisions between protons and/neutrons. The mesons (of which there are several “flavors” or types) are various combinations of quarks and antiquarks. They also carry the nuclear force within an atomic nucleus.
I won’t get into all the different kinds, though. What matters is that some mesons are lighter than protons or neutrons, with short lifespans, and decay quickly into even lighter particles.
The discovery involves two of these lighter mesons. One is pions, which are semi-stable mesons and have either a positive, negative, or neutral charge. A pion with a neutral charge will always decay to become two photons.
The other meson, called rhos, has aligned spins, unlike the other mesons, including pions. Rhos can also have negative, positive, or neutral charges. But while the pions become photons when they decay, when a rho meson decays, it becomes one positively charged pion and one negatively charged pion.
Still, following me?
So, based on what we’ve already discussed, it’s no surprise the two photons created by the split pion can be entangled. But the physicists discovered that negative and positive pions from the decayed rho meson were also entangled. This was the first time two non-identical particles of opposite charges became entangled. They also found that while pions and rhos are typically the results of a massive collision between protons, the collision isn’t mandatory. Turns out, entanglement can also occur if they are close enough when passing each other.
The research was done by physicists at Brookhaven National Laboratory (BNL) in New York and published in Science Advances on January 4, 2023. In an article about the discovery, Brookhaven physicist Zhangbu Xu said:
“We measure two outgoing particles and clearly their charges are different — they are different particles — but we see interference patterns that indicate these particles are entangled, or in sync with one another, even though they are distinguishable particles.”
Not only does their discovery unveil a new layer of quantum physics, but it also reveals the inner workings of atoms. Before this experiment, physicists thought atomic nuclei had lower energies, especially since any attempt to investigate them at higher energies had confusing results.
But this time, the researchers managed to measure the angle and speed of the pion’s impact when it struck the detectors inside the Relativistic Heavy Ion Collider (RHIC) where the experiment occurred. These measurements allowed them to analyze the shape, size, and arrangements of gluons — basically, a glue that binds quarks together — inside the atomic nuclei with remarkable accuracy.
So why does any of this matter?
Well, this knowledge could significantly impact the fields of astrophysics and quantum computing. Not to mention who knows what sort of new techno-gadgets they’ll come up with. Who knows, it might even lead to a new type of technology — which is wild to think about, considering we barely understand the technology we already use.
Perspective Shift
Granted, it’ll likely be a while before this discovery affects you or me in any tangible way. Still, knowing this new layer of quantum entanglement exists at all is tantalizing, to say the least. It’s also yet another example that we have no idea how much we don’t know. Even when it comes to entanglement, we don’t understand why it happens.
It’s clear now, though, that entanglement is abundant in the universe and happens all around us. Heck, as we previously discussed, some researchers think consciousness itself is a quantum system that uses entanglement. Now we know it can occur between dissimilar particles. So if entanglement occurs so often and in so many ways, it seems there’s a purpose behind it. Likely a vastly important one, too.
Thus far, most research focuses on one pair or group of entangled particles at a time. But, I wonder what we’d see if we observed several, even millions, entangled particle groups and/or pairs simultaneously. Maybe nothing, but sometimes I wonder if entanglement is part of a larger picture we’re missing.
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cool article! I was most intrigued by this statement "...the collision isn’t mandatory. Turns out, entanglement can also occur if they are close enough when passing each other"
I read through the Science Advances article, but my science-fu is too weak, and i was unable to find where that was mentioned. Could you please point it out, and advise, if you know, what the distance was between the two particles when passing that was enough to successfully entangle them?
It seems to me that if this can be done, then purposeful entanglement may become much easier, cheaper, and thus more readily utilised.