Lateral computing
In a quantum computer, the fundamental unit of information (called a quantum bit or qubit), is not binary but rather more quaternary in nature. This qubit property arises as a direct consequence of its adherence to the laws of quantum mechanics, which differ radically from the laws of classical physics. A qubit can exist not only in a state corresponding to the logical state 0 or 1 as in a classical bit, but also in states corresponding to a blend or quantum superposition of these classical states. In other words, a qubit can exist as a zero, a one, or simultaneously as both 0 and 1, with a numerical coefficient representing the probability for each state. A quantum computer manipulates qubits by executing a series of quantum gates, each a unitary transformation acting on a single qubit or pair of qubits. In applying these gates in succession, a quantum computer can perform a complicated unitary transformation to a set of qubits in some initial state.
Superconducting quantum computing
where formula_23 is the shape of the microwave pulse in time, formula_24 is the resonance frequency of the second qubit, formula_25 are the Pauli matrices, formula_26 is the coupling coefficient between the two qubits via the resonator, formula_27 is the qubit detuning, formula_28 is the stray (unwanted) coupling between qubits and formula_29 is Planck constant divided by formula_30. The time integral over formula_23 determines the angle of rotation. Unwanted rotations due to the first and third terms of the Hamiltonian can be compensated with single qubit operations. The remaining part is exactly the controlled-X gate.