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2.1 Key Concepts


Through blocks, items and objects you can construct, qCraft represents three fundamental concepts of quantum science in the Minecraft world. In the real world, these concepts happen on scales no bigger than a molecule, but in qCraft, they happen on the scale of entire blocks (or bigger).

Observational Dependency

Some of the earliest experiments that lead to modern quantum physics showed a surprising result: observing certain things on the subatomic level (like photons) actually caused them to have different properties. And it isn’t just that the things appear different depending on how we observe them -- like looking at the world through sunglasses makes it appear darker -- it’s that the things actually are different depending on if (or how) they are observed: as if you put on the glasses and the world itself actually became darker.

In the Minecraft world, you could think about this as a block that, when you look at it from the west, is stone but when you look at it from the south it is a pumpkin.


In the everyday, large-scale world, we tend to think things are one way or the other. For example, if I flip a coin, it’s either heads or tails. As Drs Preskill and Michalakis point out in this video, even if I cover up the coin with my hand, you know that it is either heads-up or tails-up, one or the other, even though you can’t see which one it is.

On the quantum level, however, things aren’t so simple. Quantum systems exhibit superposition: they exist in all of their possible states at the same time until they are observed. It’s as if the coin was both heads-up and tails-up while I have it covered with my hand. When I lift my hand up and you look at the coin, it then resolves to either heads or tails.

The superposition state of a quantum system (like an electron) doesn’t have to be made of up of two possibilities -- there could be many. Superposition is also central to quantum information theory and quantum computers, which process and store information using things called qubits that can be in a superposition of both a 0 and a 1, unlike the bits in a regular computer, which are always either a 0 or a 1.

Imagine placing a block in the Minecraft world that could be either a block of stone or a pumpkin. If no player was observing that block, it would exist in a superposition of stone and pumpkin. As soon as it was observed, it would become either a block of stone or a pumpkin.


Quantum entanglement refers to fact that pairs or groups of particles created together can have a special relationship to each other: their states are correlated (that doesn't mean that they have to be the same, just that they are related to each other). Experiments have demonstrated entangled behavior many times and shown that the entangled particles ‘sync up’ their quantum states instantly, no matter how far apart they are. That’s a little surprising because the particles are exchanging information faster than the speed of light, and nothing is supposed to go faster than the speed of light.

Scientists are actively researching entanglement and some belive it could lead to breakthroughs in computing and even quantum teleportation.

In Minecraft terms, this is like having an entangled pair of our superposition stone/pumpkin blocks and placing them on opposite sides of the map. As soon as one of them is observed -- let’s say it becomes a pumpkin -- we observe it's entangled counterpart and find that it, too, is a pumpkin.