As Avagadro states: "One mole of an ideal gas at STP occupies 22.4 liters." This doesn't seems counterintuitive since we know that we need a volume to compress the gas. But how can we explain quantum ideal gases. Especially in my case, Bose gases. Since well-known example is Helium 4, we might think this as our classical example in 3D (even that I'm not sure how much it is true). Interesting question that I came up with this is: What is the correspondence of 'compressing' in other dimensions? A few searchs takes me to the some definitions; quantum wire, quantum well, quantum dots. Furthermore, for my cases I found that anyons (type of quasiparticles) can occur only in two dimensional systems. I know that it's nearly impossible to give this a physical picture but maybe you can help me to undertand the meaning of the dimensions in quantum mechanics.