What is the current qubit reset mechanism on IBM Quantum devices before running a new circuit? One could either wait long enough (as much as 2 ms perhaps) in order to ensure that all qubits decay to the ground state, or could perform a soft reset by measuring each qubit and applying an X gate in case the measurement result is 1 and possibly wait some smaller amount of time before running a new circuit. The first method is definitely more robust but wastes time that could be used for running circuits. The second method is faster but not perfect, since the soft reset could fail either due to an incorrect measurements or due to a failed application of the X gate.
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According to the paper "A Thorough Study of State Leakage Mitigation in Quantum Computing with One-Time Pad" by Xu et la,[1]
Thermal Relaxation: This reset approach simply idles the qubit for a long time to allow decoherence to occur. Currently, quantum computers on most cloud platforms, such as IBM Quantum, are mainly using this approach.
reset instruction: The typical implementation of a “reset instruction” is based on a mid-circuit measurement followed by a conditional Pauli-X[...] IBM Quantum adopts this implementation.
So, thermal relaxation is used as a reset mechanism before running a new circuit, and measurement followed by a conditional-X is used for mid-circuit reset operations.
answered Feb 3 at 11:05