What are the limitations of quantum computers?
Quantum computers are exceedingly difficult to engineer, build and program. As a result, they are crippled by errors in the form of noise, faults and loss of quantum coherence, which is crucial to their operation and yet falls apart before any nontrivial program has a chance to run to completion.
What quantum computers can not do?
Real-time control. Not having any ability for I/O of any sort, a quantum computer has no capability for controlling real-time devices, such as process control for an industrial plant. Any real-time control would have to be made by a classical computer.
How are quantum sampling problems related to combinatorial problems?
Their argument revealed a deep connection between the complexity of sampling from quantum computers and conjectures regarding the average-case complexity of a range of combinatorial problems.
Are there any problems that can be solved by quantum mechanics?
SampBQP is the class of problems that can be solved when we are allowed to measure all of the output qubits. It is known that quantum mechanics produces statistics which cannot be recreated classically as in the case of quantum entanglement and Bell inequalities.
Do you need a quantum computer for quantum sampling?
The proposed quantum sampling problems do not require a quantum computer capable of universal operations and also permit physically realistic errors in their operation. This is an encouraging step towards an experimental demonstration of quantum algorithmic supremacy.
What does p x mean in a quantum circuit?
1. In the 1990s it was shown that there are families of quantum circuits for which computing p x is #P-hard in the worst-case. 18, 19 The suffix “-hard” is used to indicate that the problem can, with a polynomial time overhead, be transformed into any problem within that class. #P-hard includes all problems in NP.