What The Hell Is ”Quantum?”
2 May 2024

A Quantum In Solace: a Quantum On Its Own

You don’t know what it is, and neither do most of the folks talking about it. All you know is that it is the cutting edge beyond the cutting edge, and that ‘thought-leaders’ get teary eyed and stare off into the nothingness when they utter the word in a respectful tone. Quantum Physics upsets everything we know… Quantum computing is like the next, next, next thing. People throw it into speeches and presentations and nobody dares to ask what they mean, or test how far their actual knowledge goes or if they are simply phrase-dropping their way to fame.

Quantum. All it means is ‘the smallest possible discrete unit of any physical property’. A car is made up of parts. Parts are made out of materials. Materials out of thingies, thingies out of molecules, molecules out of atoms. And so on and so forth. This ‘so on and so forth’ – at one stage of thinking – threated infinite regression, ever smaller and smaller and smaller bits making up larger bits. Quantum Physics puts a stop to it all:

Quantum Theory & Mechanics

Quantum theory describes how particles, such as photons (particles of light), electrons, and other elementary particles, behave at the smallest scales. One of the key principles of quantum theory is that these particles exhibit both particle-like and wave-like properties, a concept known as wave-particle duality.

For instance, photons can behave like discrete particles, carrying energy and momentum, but they also exhibit wave-like properties, such as interference and diffraction patterns. This duality is fundamental to understanding many phenomena in quantum mechanics.

Moreover, in quantum mechanics, properties like energy, momentum, and angular momentum are quantized, meaning they can only take on specific discrete values rather than any value within a continuous range. These discrete units are referred to as quanta (singular: quantum).

Spooky Stuff: Quantum Entanglement

In the vast and mysterious realm of quantum physics, few phenomena are as enigmatic and intriguing as quantum entanglement. This phenomenon, which Albert Einstein famously referred to as “spooky action at a distance,” lies at the heart of some of the most perplexing questions about the nature of reality itself. This is one of those deep and meaningful discussions the Quantum people always have about… the ones that make their eyes glaze over and their voices trail of in wonderment in the distance.

At the level of quanta… (at the quantum level, as the smart folks would say) particles such as electrons, photons, and even entire atoms behave in ways that defy classical intuition. Instead of possessing definite properties like position and momentum, these particles exist in a state of superposition, meaning they can simultaneously occupy multiple states until measured.

Furthermore, quantum mechanics dictates that particles can become entangled, a phenomenon that occurs when the properties of two or more particles become correlated in such a way that the state of one particle instantaneously influences the state of another, regardless of the distance separating them. This interconnectedness lies at the heart of quantum entanglement and challenges our classical understanding of cause and effect.

In short, two quanta can be entangled. And if they are, then what you do to the one, you do to the other. The freaky bit is that the quanta don’t need to be next to each other. It’s like pricking a voodoo doll with a needle in one room, to have a person in the next room over, or on the other side of the earth, feel a stabbing pain in their chest.

Except just with quanta, not with people and not with voodoo dolls.

The concept of quantum entanglement was first proposed in the early 20th century, but its implications remained largely unexplored until the mid-20th century. Even then, its significance was not fully appreciated until the groundbreaking work of physicists such as John Bell in the 1960s. However, one notable skeptic of quantum entanglement was none other than Albert Einstein himself.

Einstein, along with colleagues Boris Podolsky and Nathan Rosen, formulated the famous EPR paradox in 1935, which highlighted what they saw as the absurd consequences of quantum entanglement. According to their argument, if two particles were entangled and then separated by a great distance, measuring the state of one particle would instantaneously determine the state of the other, violating the principle of locality and suggesting the existence of “hidden variables” that governed the behavior of particles.

It wasn’t until the 1960s that physicist John Bell proposed a theoretical framework for testing the predictions of quantum mechanics against those of classical physics. Bell’s theorem provided a mathematical inequality that, if violated by the results of certain experiments, would indicate the presence of entanglement and rule out the possibility of hidden variables.

Subsequent experiments, beginning with the work of physicist Alain Aspect in the 1980s, confirmed Bell’s predictions and provided compelling evidence for the reality of quantum entanglement. These experiments, which involved measuring the correlations between entangled particles separated by large distances, consistently demonstrated results that were incompatible with classical physics and supported the predictions of quantum mechanics.

Despite decades of experimental validation, the phenomenon of quantum entanglement remains deeply puzzling and continues to challenge our understanding of the nature of reality. One of the most perplexing aspects of entanglement is its apparent violation of the principle of locality, which states that objects can only be influenced by their immediate surroundings.

In the case of entangled particles, however, measurements performed on one particle instantaneously affect the state of the other, regardless of the distance between them. This instantaneous correlation, which defies the constraints of both space and time, has led some to describe quantum entanglement as “spooky action at a distance,” echoing Einstein’s own skepticism.

Quantum Computing

Beyond its philosophical implications, quantum entanglement also holds great promise for practical applications in the emerging field of quantum information science. The phenomenon lies at the heart of quantum cryptography, a method for secure communication that exploits the inherent randomness and privacy guaranteed by entangled particles.

Moreover, entanglement plays a crucial role in quantum computing, a revolutionary technology that harnesses the power of quantum superposition and entanglement to perform calculations exponentially faster than classical computers. By encoding information in the quantum states of entangled particles, quantum computers have the potential to solve complex problems in cryptography, drug discovery, and optimization that are currently intractable for classical computers.

From its humble beginnings as a theoretical curiosity to its pivotal role in the emerging field of quantum information science, entanglement remains one of the most profound and elusive phenomena in the universe.

As we strive to unravel the secrets of quantum entanglement and harness its power for practical applications, we are reminded of the profound admission of physicist Richard Feynman: “I think I can safely say that nobody understands quantum mechanics.” So next time someone mentions  Quantum on its own, or Quantum -Mechanics, -Physics, -Entanglement or -Computing – rest assured they are probably as clueless as you are. Indeed, the quest to understand the true nature of reality and the mysterious connections that bind the universe together is an ongoing journey—one that promises to inspire awe and wonder for generations to come.