Quantum Gate
Quantum computing logic gate.
A Quantum Gate is the equivalent of a classical logic gate (like AND, OR, NOT) but adapted for the principles of quantum mechanics. Unlike classical gates, which are often dissipative and irreversible, all quantum gates (except for measurement) are Unitary and Reversible. They operate on superpositions of states, allowing for the parallel transformation of quantum information. Mathematically, a gate is a unitary operator $U$ that acts on a state vector $|\psi angle$, such that the total probability is conserved ($U^{\dagger}U = I$).
graph LR
Center["Quantum Gate"]:::main
Pre_linear_algebra["linear-algebra"]:::pre --> Center
click Pre_linear_algebra "/terms/linear-algebra"
Pre_qubit["qubit"]:::pre --> Center
click Pre_qubit "/terms/qubit"
Rel_decoherence["decoherence"]:::related -.-> Center
click Rel_decoherence "/terms/decoherence"
Rel_bit["bit"]:::related -.-> Center
click Rel_bit "/terms/bit"
Rel_linear_optical_quantum_computer["linear-optical-quantum-computer"]:::related -.-> Center
click Rel_linear_optical_quantum_computer "/terms/linear-optical-quantum-computer"
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🧒 Explain Like I'm 5
In a normal computer, gates are like switches that turn electricity on or off (1 or 0). A quantum gate is like a magic mirror that can flip a [qubit](/en/terms/qubit), tangling it with others, or put it in two states at once. They are the 'tools' used to do quantum math.