There is a good chance that at some stage in the past year you have come across the term ‘quantum’ used in any one of a variety of contexts. It could have been while watching movies like Palm Springs on Hulu, that (spoiler alert) reference quantum physics as the reason Andy Samberg and Cristin Milioti are stuck in an infinite time loop. It could have been a reference to quantum computing in an industry rag or technology blog, or a news story about how Google or IBM seek to revolutionize programming through quantum supremacy in the shift from bits to qubits. It could have been an episode of Rick & Morty; arguably the greatest animated show of all time.
Whatever the source, this term continues to pop up more and more. In reference to the legal and compliance world, these concepts will matter with reference to quantum computing alone. Something that will become as commonplace in our vocabulary as artificial intelligence has over the past decade or so. Given the rapidly evolving nature of the tools we use and sophistication of computer programming, it is essential that we go beyond the obvious and begin to understand the world of quantum this and quantum that. These tools will impact all our lives and there is no time to waste. So, let’s have some fun and explore the term quantum through the lens of quantum mechanics in as brief as concise a summary as possible. Trust me, it may seem dry and boring, but by then end of this post you will be scratching your head and googling for more.
Quantum entanglement (a primary feature of quantum mechanics) can be described with the example of two particles, far apart in space, which have behaviors that are correlated. This means if you do something with one particle it will have an instantaneous correlation with what happens to the other particle, regardless of how far apart they are. Albert Einstein referred to this as “spooky action at a distance”; you do something in Hong Kong and in some way, it has an impact on a quantum particle in Nairobi. This phenomenon can be described mathematically, but there is currently no layman’s explanation for what is occurring here. At least in the way one would describe gravity to a classroom. What the math can determine is that the particle in Hong Kong has a quantum wave that stretches to Nairobi (and way beyond). When you interact with the particle in Hong Kong you effect that probability wave instantaneously. Therefore, you change the wave in Nairobi, even though your action was in Hong Kong.
The math is solid. This has been demonstrated through making predictions that can be tested in the laboratory. All we really want from a physical theory is for it to give a rigorous articulation of what happens out there in the natural work. Erwin Schrodinger realized that if two particles have been together for a while and then separate, they can no longer be thought of as independent or autonomous. Schrodinger discovered in the math that what you did to one particle would have an effect in some quantum mechanical way on the other. In 1935 Einstein wrote a paper which leveraged this idea. In the paper, Einstein tried to prove that quantum mechanics cannot be the full story of the world because of this weird quality of what you do in one place having an impact on something far away.
It was not until the 1980s that the testing of these theories gained steam. Today, quantum mathematics is used all the time in the laboratory, making the leap from theoretical to applied physics. It is no longer theory, it is real. The difficulty with comprehending quantum entanglement is the human brain struggling for intuition. The reality is that we can physically demonstrate that two apples plus two apples equal four apples. Our intuition simply takes care of that. We can see it, understand it, and not require any further discussion. But quantum entanglement is not such a simple concept for our minds to adapt. What physicists have found is that everyday phenomenon is a small slice of the way the world is put together. But when you can see your life and your experiences as a tiny sliver of a reality that is bizarrely strange and utterly wonderous, from black holes to time dilation to quantum tunneling, it changes things.
So, what is actually happening here? Well, if you want to allow for the most exotic possibilities, some suggest that you are probing the many worlds of quantum mechanics. In quantum mechanics all you are really doing is predicting the probability of one thing happening or another; an electron has a 70% chance of being here or a 30% chance being there. If you measure the electron and you find it over here, what happened to the other electron? Some physicists are suggesting that it still exists, but in another world, where another copy of you finds the electron there. However, you are not aware of the other you, so you believe that you are the unique version of you. According to quantum mechanics there could be two of you, each found in one location or another. That is the way quantum mechanics works. The phrase many worlds could be substituted for alternate reality, multiverse, etc. Again, this has been proven in the math and tested in the laboratory, it just makes no sense to our intuition given how we presently understand the laws of physics and our experience of the phenomenon we can see and therefore comprehend.
The way we can improve understanding of this concept is to think of quantum mechanics as non-local. Non-local means that the influences are not limited to where they are applied. Our experiences and influences are local. For example, if I take a bite out of a sandwich, the physical influence on the substance is within my physical neighborhood (hence local). To me, taking a bite out of the sandwich did not affect something on the other side of the world. However, quantum mechanics stipulates that this intuition is built up from everyday experience, and everyday experience is grossly misleading when it comes to these ideas. It is, in a word, severely limiting.
For people who understand this quantum entanglement does not seem weird at all, because in one world you have a certain correlation between the particles and in another world you have a different correlation between the particles…and that’s just what happens. Again, we can demonstrate and prove this in the math, but our intuition and understanding of the physical world makes it a difficult concept to comprehend. Simply put, this explanation allows for the possibility of multiple universes. Have fun wrapping your walnut around that.