Testing the context-independence of quantum gates

Understand

The actual gate performed on, say, a qubit in a quantum computer may depend, not just on the actual laser pulses and voltages we programmed to implement the gate, but on its {\em context} as well.

• For example, it may depend on what gate has just been applied to the same qubit, or on how much a long series of previous laser pulses has been heating up the qubit's environment.
• This paper analyzes several tests to detect such context-dependent errors (which include various types of non-Markovian errors).
• A key feature of these tests is that they are robust against both state preparation and measurement (SPAM) errors and gate-dependent errors.