CASCADE RELAXATION-BASED METHOD AND APPARATUS FOR READING SUPERCONDUCTING QUBIT

摘要

A cascade relaxation-based method and apparatus for reading superconducting qubits, the reading method comprising: before reading, extending in advance the time that it will take for a superconducting qubit to be measured to relax to a ground state; and reading the state of the superconducting qubit to determine a logic state corresponding to the superconducting qubit. In one embodiment, before reading, an excited state component of the unknown-state superconducting qubit is excited to a higher energy state in order to extend the time that it will take for the superconducting qubit to relax to the ground state. By suppressing the rate at which the qubit relaxes to the ground state, and especially the rate of relaxation to the ground state at the initial stage of measurement, the probability that the qubit will relax to the ground state within the reading time is greatly reduced, which ensures that during a measurement process, it is highly probable that the qubit will stay in the excited state or the ground state, which prevents measurement errors in which due to a very fast rate of relaxation to the ground state, the qubit will have already relaxed to the ground state by the time that readings are taken; additionally the foregoing helps to extend the reading time so as to improve the reliability in taking readings.