Is Quantum Physics used in manufacturing CPUs? If I remember correctly, I heard some people saying that the transistors on CPUs today are so small, that they have to use quantum physics to make CPUs. Is that correct?
 A: There will be several teams of CPU designers - Logic Designers, Logic Implementation, Data Integrity, Data Storage, Data Transmission, materials research and then a management team. logic implementation will most likely have physics specialists who advise on a plethora of issues. They would be expected to look at new designs and decide whether the implementation would fail due to the physical constraints and effects of the materials they use. They have to have a firm grasp of all aspects of microelectronic physics - Thermodynamics, Quantum Physics, Electromagnet effects etc. things like alteration of electron speed as it passes through different materials has to be considered so data arrival times are consistent. It is very likely that that the CPU Caches use Quantum Tunnelling for data retention, and the  Cache blocks are probably kept seperate from the Transistor arrays to minimise quantum interference.
A: Quantum mechanics is part and parcel of understanding the function of any transistor, and therefore any integrated circuit.
As component sizes have gotten smaller, tunneling has become an increasingly important limiting factor in the design and layout of chips.
A: Well, they are not using it, but taking into account.
Tunneling is one of the most important:
1) As gate oxide thickness is just 1-2nm, electrons can tunnel through it -> power consumption increases (or transistor might turn itself on if gate is not connected at the moment). So if you replace usual SiO2 with high-K dielectric (like HfO2) you would be able to increase gate oxide thickness (=dramatically reduce tunneling) but electromagnetic field will remain the same (i.e. transistor would work exactly as with thin oxide)
2) Flash memory directly rely on quantum tunneling effect - electrons into strong electromagnetic field tunnel right into middle of dielectric, and form 'trapped' charge, which may stay there for years.
A: Otherwise instead of "fight" these phenomena, like tunnelling, you can think a new solution :
From http://en.wikipedia.org/wiki/Quantum_computer

A quantum computer is a device for computation that makes direct use
  of quantum mechanical phenomena, such as superposition and
  entanglement, to perform operations on data.

On the Wikipedia page you can see the photograph of a chip constructed by D-Wave Systems Inc., designed to operate as a 128-qubit superconducting adiabatic quantum optimization processor.
I am not an expert, I understand that quantum computing can be explained as :


*

*put in the N input data as a physical quantity of the system,
repeated N times

*let's the physical system evolves and finds its natural quiet
state

*measure the N new values of the chosen physical quantity : this
set is a possible solution of the problem ( and reading it is also the most
challenging task )

*repeat from 1. until you find satisfactory output data sets


For certain classes of problems, quantum computing seems to be the best path to solve them.
An example, solving a classical search problem - see the demo on the marvellous Wolfram web site :
http://demonstrations.wolfram.com/QuantumComputerSearchAlgorithms/
