Quantum Definitions for the Common Good: The First List

For those folks who are well traveled and/or have been to locations akin to Iceland, Uyuni, Waipu, or other "out of this world" places, this world of quantum gives those same vibes. 

It is amazing, seems unexplainable, and basically makes you take a step back and REALLY evaluate what reality is, and where we fit within a very delicate (but robust) framework. Oh, and btw, we've yet to work it all out. Some of it's still theoretical, lots of it is scattered across the world in the labs of smart folks, and a LOT of us are planning out the future. For everyone else, there's this quick reference guide: 

Some reading material that might help 

• Douglas Adams; Restaurant at the End of the Galaxy (Improbability, Whales, and Petunias)
• Whiteson/Cham; We have no Idea: A guide to the Unknown Universe
• Phillip Kaye, Raymond Laflamme, and Michele Mosca; An Introduction to Quantum Computing
• Quantum Computing for Everyone; Chris Bernhardt
• WWT's website; You know I had to blow our own trumpet for a moment… ton of good material on Q!

Quantum computing: What is it? 

• The turbo button (for those of you old enough to remember those on the old 386's)
• The engine being built TO speed it all up (Once we can untangle AI)
• It's our FFWD button to answers (IF we can work out the right questions)
• It'll be the core compute later in the next evolution of how we use and interact with technology

Some basics to consider

• Particles are waves, and waves are particles, everywhere, everything, all at once (until we look at it…)
• Quantum states are discrete, everything likes its order and exactness, there's no "ish" when counting
• It's ALL probability and prediction. Will the sun come up tomorrow? "Probably" is always the answer
• It's not certain until someone measures it (and nails it down), AND then it (the particle) stays that way
• Spooky IS a word used when we talk about entanglement. Two particles, separate BUT connected
• Everything not forbidden IS not only possible but mandatory, no matter how absurd
• There IS a grounding in classical physics, it's not magic, but it DOES kinda look like it sometimes
• Classic world: "There's no such thing as a ½ integer" Quantum Mechanics: "Hold my beer". I rest my case.

A shout-out to WWT's Atom AI and the team behind it for the help in refining and double-checking some of the answers and ways to phrase them. 

Coherence: 

• Coherence is the delicate state in which quantum particles can fully express their uniquely quantum behaviors — remaining in superposition, sustaining entanglement, and enabling powerful effects like interference, amplification, cancellation, and complex quantum computation. It is the essential ingredient that allows a quantum system to function as something fundamentally different from a classical machine.
• However, coherence is extraordinarily fragile. Any interaction with the outside world — heat, vibration, stray electromagnetic fields, cosmic rays, or tiny imperfections in the engineered hardware — can disturb a qubit's quantum state and cause it to lose its special properties. This collapse into classical behavior is known as decoherence, and it remains one of the primary constraints holding back large‑scale quantum computing.
• Because coherence is limited, modern quantum technologies must operate within the narrow window of time that coherence survives. Different hardware platforms (such as superconducting qubits, trapped ions, photonics, spins, and neutral atoms) exhibit different coherence times, creating diverse engineering strategies across the industry. As systems scale to larger numbers of qubits, maintaining coherence becomes even more challenging due to noise, crosstalk, and the complexity of controlling many qubits simultaneously.
• In short: coherence is the cornerstone of quantum technology — without it, the "quantum" in quantum computing disappears.

Coherence Times: 

• T₁ (Relaxation Time) 
  How long a qubit retains its energy state before it naturally "relaxes" (Decays). This reflects energy loss to the environment.
  • Think of it like a kid standing on a chair pretending to be tall. T₁ is how long they can stay standing before they flop back down into the normal seated state. That flop is the qubit losing energy.
• T₂ (Dephasing Time) 
  How long a qubit maintains its relationships — crucial for interference and superposition. T₂ captures the loss of quantum information due to noise, fluctuations, and environmental disturbance even when energy levels stay the same.
  • Imagine two dancers perfectly in sync. T₂ measures how long they stay coordinated before one of them gets distracted, looks at the audience, or forgets the move. The dancers are still on stage, but the harmony — the phase — is gone.

Decoherence: 

• It is when the quantum state of a system loses its quantum properties, such as superposition and entanglement, due to interactions with its environment. This causes the system to behave more like a classical system (normal rules and laws we understand), where quantum effects are no longer observable.
  • Imagine a spinning top, when it's spinning smoothly; it represents a quantum state with all its unique properties. However, if you poke the darn thing or nudge it into another object then it will encounter friction, at which point it'll start to wobble, slow down, and eventually fall over. This interaction with the environment is akin to decoherence, where the quantum state is disturbed and loses its special characteristics.
• Quantum kryptonite. When you can find AND measure the damm thing, it loses its cape and becomes Clark Kent.
  • Changing states (and focus/profile/etc.)
• This is the Monday morning when we all must go back to being "normal" after a weekend of fun and chaos.
• CAN happen on its own; the whole "quantum state" is as fragile as an ostrich egg balanced on a burning 
  match.

Electrons: 

• The Leatherman of the quantum realm because of the numerous ways they are used as the basic unit of information (bits/qubits). Some of the applications are listed below (and described separately under their own definitions elsewhere in this doc).
  • Qubits: In traditional computing, information is stored in bits, which can be either 0 or 1. In quantum computing, information is stored in qubits, which can be both 0 and 1 at the same time, thanks to superposition. Electrons can be used to create qubits because they have properties that allow them to exist in multiple states simultaneously. (Welcome to the whole particle/wave/etc.)
    • Unlike electrons, protons, or neutrons — which are particles — Qubits are not a particle but a framework that particles operate in. Electrons are a popular particle to use for qubits because they are easily measured and can exist in multiple quantum states at once, making them ideal for representing the "0 and 1 at the same time" superposition that quantum computing relies on. By choosing different physical systems (electrons, photons, ions, neutral atoms, superconducting circuits, and more), we can build qubits in many forms — each with its own strengths, weaknesses, and engineering headaches.
  • Superposition: Imagine an electron as a tiny sphere that can spin in different directions. In quantum computing, this "spin" can represent different states. An electron can be in a state where it's spinning both up and down at the same time, which is what allows qubits to hold more information than classical bits. (Especially relevant when you have multiple qubits working on a problem simultaneously)
  • Entanglement: Electrons can also become entangled, meaning the state of one electron is linked to the state of another, no matter how far apart they are. This property is used in quantum computing to perform complex calculations much faster than classical computers. (A digital take on identical twins)
  • Quantum Gates: Just like classical computers use logic gates to process information, quantum computers use quantum gates to manipulate qubits. Electrons, with their quantum properties, are manipulated using these gates to perform calculations.
• Using electrons also allows for interacting with the following:
  • Silicon spins where individual electrons are confined in a nano-scale silicon structure (basically a molecular prison cell) and monitored. This tends to leverage existing types of semiconductor manufacturing for scale/cost, etc. (Good for rapid prototyping, testing, and analysis.)
  • Helium, no, they're not breathing and speaking in a funny voice, they're held on the liquid helium surface, which helps a ton with longevity of the measurements/experiments/qubit state/etc. It's an interesting field that's getting a lot of focus because it can "hold" a quantum state (and therefore quantum information) for an extended time (compared to current alternatives).
  • Trapping (catch and release for qubits) using ruddy great magnet fields

Entanglement: 

• Entanglement is one of those concepts in quantum physics that makes sense right up to the point where you go "how" at which point you need to (like the rest of us) suspend your existing beliefs and accept things "just work" sometimes. So, what is it?
  • It's where two or more particles become linked in such a way that the state of one particle instantly influences the state of the other, no matter how far apart they are. This connection is so strong that even if the particles are separated by vast distances (think practical earth-space, theoretical across the universe), a change in one will result in a change in the other.
  • Imagine you have a pair of dice. When you roll one die, and it lands on a number, the other die, no matter where it is in the universe, will instantly show the same number. This happens without any discovered communication between the two dice. In the quantum world, this is a real phenomenon and is a fundamental aspect of how particles behave.
• Other ways to think about it, look at it, or try to understand it:
  • Twin (moody) identical teenagers, poke one of them, the other one goes "ow!" instantaneously, BUT you don't know about it (or hear about it) until you receive a message confirming it the traditional way (thus not breaking FTL (Faster Than Light) and causality…
  • In summary: The process of entanglement happens instantaneously; the revelation of it does not. We must use good old-fashioned not-faster-than-light communication methods to piece together the correlations that quantum entanglement demands, thus maintaining causality and avoiding the end of the universe (just yet…)

Heart of Gold: 

• It's a fictional (at least in this universe) spaceship featured in Douglas Adam's 'The Hitchhiker's Guide to the Galaxy'. Its main feature is that its propulsion systems works through an Infinite Improbability Drive. (How does this tie into Quantum? See next note…) This starship is the first to make use of an Infinite Improbability Drive and features top-of-the-range Genuine People Personalities (or GPPs), courtesy of the Sirius Cybernetics Corporation, who are known for being an inept company that creates largely useless devices.
• Quantum mechanics is a probabilistic theory, while improbability is often used in a statistical sense. Quantum Improbability can refer to events with extremely low probabilities predicted by quantum mechanics. (With me so far?) Quantum probability is calculated using complex numbers (numbers that have both real AND imaginary parts…don't ask, we'll cover that in a moment!) called probability amplitudes whose squared moduli (fancy way of saying we measure things) give the actual probabilities. This means quantum theory predicts probabilities for all possible outcomes of an event, rather than a single deterministic outcome.
• What this means in English is that somewhere, somehow there IS a bowl of petunias wondering why they're afraid of heights, and a whale that's finally found a friendly landing spot on the ground.

Heisenberg uncertainty principle:  

• Let's break this down…. In the "real" world, when you get stopped for speeding, the officer knows it's you, where you were, what you are driving, AND what speed you were going… yes?
• In "our" quantum world, when you get stopped by the officer, and they tell you, "You were going 100mph… we don't know where, but dammit, you were speeding! OR they come up to the window and ASK you what speed you were going because they know it was you, but heck if they know what speed you were doing… THAT's Heisenberg in practice. HENCE, next time you get stopped and they ask you, "Do you know what speed you were doing?" You can honestly answer that "According to Heisenberg's uncertainty principle, because WE are now here talking about it, I cannot honestly say NEITHER of us knows what speed I might have been doing" (PS, I am NOT a lawyer, etc.)
• Simply put, in the normal world, we can measure ALL sorts of things (speed, location, etc.) BUT in the quantum world, the closer we get to measuring one thing (location/position), the harder it is to pin down the other (speed/momentum)
• To further elaborate/break it down: In the quantum world, certain pairs of measurements—like position and momentum for particles, or phase/flux and charge in superconducting circuits—are fundamentally linked so that the more precisely you pin down one, the more the other becomes smeared out.
  • It's not a failure of our instruments; it's the way nature itself is wired. A helpful analogy is squeezing a balloon: the tighter you grip one end, the more the other end bulges unpredictably. That's exactly how quantum "conjugate variables" behave—control one, and the other becomes inherently uncertain. Superconducting‑qubit designers exploit this on purpose: instead of fighting uncertainty, they shape it. For example, in transmon qubits, engineers deliberately make the charge highly uncertain so that the phase becomes stable and robust, giving them a qubit that's easier to control and less sensitive to noise. In short: in quantum physics, some quantities simply don't have sharply defined values at the same time, and modern qubit architectures harness that fact—rather than struggle against it—to build reliable quantum hardware.

Interference: 

• Behavior again, this time talking about waves.
  • Ironically, the same type of behavior you get when looking at the sea or a lake.
  • Waves (wet ones) help each other, or cancel each other out when they collide
  • Just like a surfer, you are looking for JUST the right wave…
  • Oh, and most of the other stuff we've talked about hinges on this part, so it's important!
• In classical engineering, "interference" usually means an unwanted disturbance, but in quantum systems, it's the central tool scientists intentionally use to shape outcomes. Quantum particles behave like waves, and when these waves overlap, they can reinforce or cancel each other. By engineering these interference patterns, researchers amplify desirable results and suppress undesirable ones, enabling powerful capabilities across quantum technologies. Interference guides algorithms that reveal hidden periodicity in mathematical structures (as in the phase‑estimation step of Shor's algorithm), strengthens the signal of correct answers in search spaces (as in Grover's amplitude‑amplification techniques), and enhances quantum sensing by making tiny physical changes more detectable.

LHC (Large Hadron Collider) 

• It's a high-speed molecular NASCAR track (or F1 for those in Europe/Rest of the world)
• It is the world's largest and most powerful device for smashing protons (Lego blocks of the universe) together.
• Located at CERN on the Franco-Swiss border, a 27,000-meter (underground) ring of superconducting (bloody cold) magnets that recreates conditions from the moments after the Big Bang.
• It's collaboration in action. Over 10,000 scientists, 100+ countries, all working together to explore and understand the building blocks of our universe.
• Why? Because sometimes we must tear things apart to work out how they work (and would go back together)

Petunias (Bowl thereof) 

• Probability states that (famous last words) anything and everything is possible (and given the ridiculous number of galaxies out there, it's probable too), therefore, when the Heart of Gold (from Douglas's book) is fired upon by a defense system, the two missiles find themselves unexpectedly turned into a bowl of petunias and a whale.
• The whale is covered elsewhere, yet the petunias simply think "oh no, not again" thus two things are deduced… firstly this existential existence we live in is maddeningly ridiculous, complex, and absurd (because we don't fully understand it) AND (spoiler) we've met this poor character before in other guises and they always manage to suffer for no apparent reason.

Photons: 

• The Lamborghini of the molecular world, no mass, no charge, just buzzing around with that "look at me" attitude
• One of the building blocks of quantum computing, as they are good at room temperature operations
• Great for certain experiments, but challenges with interactions, scale, and losses (hmmm, Lamborghini again)

Quantization: 

• The Babel fish of mathematics. This is where we take what we know and wrap it around the quantum realm
• Energy and momentum can ONLY exist in specifics, no faffing around trying to work out what it is…
  • Rounding and truncating, think of this as digital signal processing…
• This is where our moody, indecisive teenagers got to plan and pick a value/focus/effort/etc.
  • But it must be all in, no 1/2 efforts!
• At an atomic level, it's rather handy as it means things stick together and are stable
  • No, the potted plant isn't going to turn into a whale (just yet…)
• However, by moving data from high to lower precision, despite speeding things up we DO get accuracy issues

Quantum Circuits: 

• Same basic principle as a normal electronic circuit, built with logic gates and used just like Legos.
• More specialized than your normal silicon circuit, you CAN practice in the comfort of your office (Qiskit/Cirq)

Quantum Hardware: 

• The stuff that makes it all work, AND (like our normal silicon computers) there's a host of options:
  • Superconducting Quantum Computers
    • The ones we're used to seeing on TV. Supercooled, looks like alien tech, and geeky as all heck!
    • Need ultra cool, complex systems to work, still lots of noise and interaction challenges
• Topological Quantum Computers
  • This makes Quantum look sane. Based on two-dimensional, exotic particles, they can be more stable
  • Good error resilience and fault tolerance, but a LOT of work to do, complex as heck and limited development
• Trapped Ion Quantum Computers
  • Think of this as another approach to beating up on atoms, this time with lasers and vacuums!
• Photonic Quantum Computers
  • Light particles (photons) are used with optics. No need for supercooling, but bloody complicated
• Neutral Atom Quantum Computers
  • Using lasers as chopsticks to trap certain atoms, yeah, it's harder than it sounds.
• Quantum Dots Quantum Computers
  • Uses stuff we understand (existing semiconductor tech) BUT still trapping electrons is hard work!

Quantum Measurement: 

• This is where we take ALL the gubbins you've read about and get to apply "classical" mathematics to it.
• Oh, just because we measured something as "x" once doesn't mean it'll do the same again if we re-run it
• Classical flip a coin, it's in the air, it could be ANYTHING, once it lands, it's measured…

Quarks: 

• Quarks are fundamental particles that are the very basic (as far as we currently know) building blocks of matter. They combine in specific ways to form protons and neutrons, which in turn make up the nucleus of an atom. Quarks are, as far as we can tell, never found alone in nature; they always exist in groups, bound together by a force called the strong nuclear force.
• Thinking of them as the tiny Lego bricks that snap together to build the larger structures of matter often helps with visualizing them. Just as you can't always see the individual Lego bricks inside a completed model, you can't see quarks directly, but they are essential for forming the particles that make up everything around us.
• There are six types, or "flavors," of quarks: up, down, charm, strange, top, and bottom. The most common quarks, up and down, combine to form protons and neutrons. The other types of quarks are found in more exotic particles and are usually produced in high-energy environments, such as those in particle accelerators. (We'll talk about Leptons at some point, I promise!)

Schrödinger Equation: 

• The cookbook for understanding some of this peculiar world
• Quantum's version of Newton's laws of motion, a guide to working out how (and why) things happen
• Simply put, it's a 100-year-old way of looking at how the very basic building blocks of our universe work
  • Or should work, or might work, or at least work when we're looking at them

Spin: 

• Spin is a fundamental property of particles, similar to charge or mass. However, unlike a spinning top or a planet rotating on its axis, quantum spin doesn't refer to actual physical spinning. Instead, it's an intrinsic form of angular momentum carried by particles.
• To explain it a little differently, imagine it as a tiny arrow that points in a specific direction. This arrow can point up or down, and these directions are used to describe a particle's spin state. For example, electrons, which are particles that orbit the nucleus of an atom, have a spin that can be either "up" or "down."
• It's also crucial in quantum mechanics because it affects how particles interact with each other and with magnetic fields. It's a key factor in the behavior of atoms and molecules, influencing everything from the structure of the periodic table to the properties of materials. (Which is why we complicate things even more by giving them additional rotational behaviors to work out what they're doing and what they are…)
• Congratulations, you exist, you have brown hair, dark complexion, blue eyes, and ½ Integer spin, you're an electron (and a fermion family member).

Superposition: 

• Moody non-committal teenager that wants to do both everything and nothing on a family holiday
• You know that "does a falling tree make a sound if nobody hears it…." Yea, this is quantum's version
• It's when we turn assumptions into reality, where do you think the teenager is vs. where ARE they…

Uncertainty Principle: 

• You know that moment when you're trying to swat a fly or a mosquito, this IS that.
• You know where it IS the moment you try to squash it, but you underestimated its speed
• OR you see it coming towards you, swat where it should be, and the damm things buzzing in your ear…

Wave-particle Duality: 

• This is the "oh, for crying out loud! Make up your mind" portion of quantum
• Is it a bird, a plane, Superman, or just a particle that can't make up its mind…
• Basically, this IS that part of science where you DO influence something by just looking at it…

More things to expand upon: 

• An overall "where are we, and what's still being worked on/discovered?"
  • Rishon Model
  • Topological Braid Models
  • Unified Hyperparticle Models
  • Technicolor, Haplons and Leptoquarks, where do we stand?
• Grovers' Algorithm
• Complex Numbers
• Fermions
• Leptons
• Plank, Planks, Planc, we'll work it out...
• Probabilistic Theory
• Probability
• Quantum
• Squared Moduli
• Standard Model of Particle Physics (Mass, Charge, Spin, ½ Integers)

More about the lead authors

Before we forget: Who to blame for this? 

Valentino Esposito: 

Hi! My name is Valentino Esposito. I'm a Technical Associate within the World Wide Technology Associate Academy, having joined the team in 2025. Some facts about me: I served in the U.S. Army, working in leadership and satellite communications. I live in the country and love the lifestyle. Outside of work, I'm a full-time husband and love my job. Learning about quantum concepts to share with others is a passion of mine, and I've had the great pleasure of working with Chris Roberts to develop material we think is readable and digestible for our WWT population.  

To the readers of this material, I hope that you learned something and that your curiosity has been sparked! 

Chris Roberts:

Chris has been at WWT since 2025 and has been lurking around our industry since before its inception (the lack of hair helping to identify this). His most recent projects have been focused on the aerospace, deception, deepfake, identity, cryptography, AI/Adversarial AI, and services sectors.