Diagnostic apparatus

A diagnostic system comprising:

• a first array of test circuits;
• a second array of superconducting quantum interference devices (SQUIDs), wherein each SQUID of the second array is coupled to a test circuit of the first array such that an electronic noise present in the test circuit induces a first current that flows through each SQUID of the second array;
• and
• a current source configured to provide a second current for each SQUID of the second array such that the second current flows through each SQUID of the second array, wherein each SQUID of the second array is configured to generate an output in a form of:
• a first voltage in response to a sum of the first current and the second current being less than a threshold current,
• wherein a magnitude of the second current that flows through the SQUID is increased at a linear rate while generating the first current, and
• a second voltage in response to the sum of the first current and the second current being greater than the threshold current.

A method of operating a diagnostic apparatus, the method comprising:

• generating, by the diagnostic apparatus and for each superconducting quantum interference device (SQUID) of a first array of SQUIDs and a corresponding test circuit of a second array of test circuits, a first current within the SQUID in response to detecting an electronic noise within the corresponding test circuit;
• increasing, by the diagnostic apparatus and for each SQUID of the first array, a magnitude of a second current that flows through the SQUID while generating the first current;
• and
• determining, by the diagnostic apparatus and for each SQUID of the first array, the magnitude of the second current at which an output of the SQUID transitions from a first voltage to a second voltage,
• wherein determining the magnitude of the second current comprises:
• using a magnitude of the first current and a time elapsed between a time of the first current to the transition to infer the magnitude of the second current when the SQUID transitions from the first voltage to the second voltage,
• wherein the first voltage is output in response to a sum of the first current and the second current being less than a threshold current, and
• wherein the second voltage is output in response to the sum of the first current and the second current being greater than the threshold current.