Re:The Machine of Tomorrow Today: Quantum Computing on the V...
by reikonomusha on Wednesday June 14, 2017 @12:40PM
(#14553901)
Universal quantum computers do indeed exist. It's true that some quantum devices are special purpose (e.g., D-Wave's annealers), but most groups doing quantum computation are doing universal gate-based machines (e.g., Rigetti, Google, IBM, etc.). They're just being made at small scales right now (2-50 qubits).
Re:The Machine of Tomorrow Today: Quantum Computing on the V...
by nabla9 on Wednesday June 14, 2017 @02:45PM
(#14554984)
These are still using quantum circuit model. Universal quantum gates are universal because they can be can be used to build any circuit.
Programming the quantum computer means designing the circuit. Gates are reconfigured for each algorithm.
These models are computationally equivalent of course.
Each quantum computer is special purpose circuit implementing single algorithm.
Because quantum computation works trough destructive interference, there is no interaction during execution. You insert the input, run it trough circuit and extract the result as classical output at some point. The whole setup science experiment looking gadget sitting in the lab (with the exception of Dwave).
Universal quantum computer (aka Quantum Turing Machine) is concept used in computational complexity theory. I'm not aware of any suggested physical implementation of universal programmable quantum computer. I don't even know if it makes any sense.