Algorithmic cooling
A qubit (or quantum bit) is a unit of information that can be in a superposition of two states, denoted as formula_1 and formula_2. The general superposition can be written as formula_3where formula_4 and formula_5. If one measures the state of the qubit in the orthonormal basis composed of formula_1 and formula_2, one gets the result formula_1 with probability formula_9 and the result formula_2 with probability formula_11.
Quantum bus
A quantum bus for superconducting qubits can be built with a resonance cavity. The hamiltonian for a system with qubit A, qubit B, and the resonance cavity or quantum bus connecting the two is formula_1 where formula_2 is the single qubit hamiltonian, formula_3 is the raising or lowering operator for creating or destroying excitations in the formula_4th qubit, and formula_5 is controlled by the amplitude of the D.C. and radio frequency flux bias.