A Quantum Processing Unit (QPU) is a physical or simulated processor that contains a number of interconnected qubits that can be manipulated to compute quantum algorithms. It's the central component of a quantum computer or quantum simulator.
Quantum devices are still an emerging technology, and not all of them can run all Q# code. As such, you need to keep some restrictions in mind when developing programs for different targets. Currently, Azure Quantum and the QDK manage three different profiles for QPUs:
* Full : This profile can run any Q# program within the limits of memory for simulators or the number of qubits for physical quantum computers.
* No Control Flow : This profile can run any Q# program that doesn't require the use of the results from qubit measurements to control the program flow. Within a Q# program targeted for this kind of QPU, values of type Result don't support equality comparison.
* Basic Measurement Feedback : This profile has limited ability to use the results from qubit measurements to control the program flow. Within a Q# program targeted for this kind of QPU, you can only compare values of type Result as part of conditions within if statements in operations. The corresponding conditional blocks might not contain return or set statements.
