Fredkin Gate
| Entrances | Outputs | |||||
|---|---|---|---|---|---|---|
| C. | I 1 | I 2 | C. | O 1 | O 2 | |
| 0 | 0 | 0 | 0 | 0 | 0 | |
| 0 | 0 | 1 | 0 | 0 | 1 | |
| 0 | 1 | 0 | 0 | 1 | 0 | |
| 0 | 1 | 1 | 0 | 1 | 1 | |
| 1 | 0 | 0 | 1 | 0 | 0 | |
| 1 | 0 | 1 | 1 | 1 | 0 | |
| 1 | 1 | 0 | 1 | 0 | 1 | |
| 1 | 1 | 1 | 1 | 1 | 1 | |
The Fredkin Gate is a circuit invented by Edward Fredkin that is used for reversible computing . Input and output consist of three bits . If the first bit = 1, the other two bits are swapped with one another; if it = 0, no exchange takes place.
An important property is that the Fredkin Gate is "conservative", that is, the output has the same number of ones as the input. Since there is no loss of information, the operation is completely reversible.
Logical function with exclusive-OR and AND - gates
O 1 = I 1 XOR S
O 2 = I 2 XOR S
with S = ( I 1 XOR I 2 ) AND C
literature
- Joachim Stolze, Dieter Suter: Quantum computing. A short course from theory to experiment . Wiley-VCH, Weinheim 2008, p. 33, ISBN 978-3-527-40787-3 .