- In current designs, the quantum processors require storage at low temperatures in a cryostat leading to a distinct physical separation between the classical and quantum hardware. - Coupling takes place by exchanging classical information. - In application of this hybrid quantum/classical approach, the quantum processor acts like a **coprocessor with the quantum processor dealing with selected computationally demanding tasks** - The quantum processor receives information from the CPU, and this is used to initialize the quantum state in the quantum processor. - During the quantum simulation, the quantum state is transformed by application of quantum gates in quantum circuits. - Then measurement operations are used to extract classical information from this quantum state, and this is subsequently passed to the CPU.  - Since in quantum mechanics a measurement leads to the (partial) collapse of the quantum state, in the hybrid classical/quantum approach, typically multiple realizations of the quantum state are needed to obtain classical information with acceptable levels of noise and [[uncertainty]]. - It is important to recognize that, since initializing a particular quantum state in quantum computer can be a significant challenge, this hybrid approach can only be expected to lead to significant computational speedups in case the quantum simulation is significantly faster for the selected problem than conventional solution methods.