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Ket 0 and Ket 1

The quantum mechanical version of a bit is a qubit, and has two basic states, ket 0 and ket 1. You write it as

|0⟩  and  |1⟩



That looks much like the well-known numbers 0 and 1, which you can save in a bit. A bit has a value of 0 or 1 (on or off - whatever you want to call it) but not both values.

By superposition of several qubits, different strings can be expressed simultaneously. In this way, four qubits can have both the value 1010 as well as 1101. In a quantum byte (8 qubits) you can store 256 series, which then again can be read out separately.

You will say that this is not possible.

Yet it is like that. Researchers at the Technical University (TU) of Delft managed in 2007 to perform operations with two qubits. These are the first steps on a long road to a quantum computer.

There is only one word – incomprehensible.


Additional information

The British quantum physicist Paul Dirac invented this notation.


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