This does not prevent quantum circuits for the discrete Fourier transform from being used as intermediate steps in other quantum circuits, but the use is more subtle. We are building a full stack of flexible software to run novel and complex algorithms, exploiting the full potential of quantum computation. Join our team Be part of delivering a truly revolutionary product to the world. Read Edit View history. This issue is carefully discussed in Kitaev's article. This condition assures that intermediate "garbage" is not created the net physical effect would be to increase entropy, which is one of the motivations for going through this exercise. Cambridge: Cambridge University Press. Anti-gravity Acoustic levitation Cloak of invisibility Digital scent technology Force field Plasma window Immersive virtual reality Magnetic refrigeration Phased-array optics Thermoacoustic heat engine. Specifically, such a subcircuit looks like:. This difference can at times lead to confusion, so it is important to note this significant difference between the linear algebraic notation and quantum circuit diagrams.