key is created between the two parties through a public channel. Quantum cryptography can be considered a state of entanglement between two multi-dimensional systems, also known as two-qudit (quantum digit) entanglement. See also Bell test experiments Bell's inequality EPR paradox GHZ state Superdense coding Quantum teleportation Quantum cryptography Quantum circuits Notes References , pp. 25. , pp. 75. . Quantum information science