Diagnostic device
A diagnostic device includes a probe, a motor configured to scan the probe over a test circuit, a superconducting quantum interference device (SQUID) attached to the probe and configured to be coupled to the test circuit such that an electronic noise present in the test circuit induces a first current that flows through the SQUID, and a current path configured to receive a second current that flows through the SQUID. The SQUID 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, and a second voltage in response to the sum of the first current and the second current being greater than the threshold current.
1 . A diagnostic device comprising:
a probe;
a motor configured to scan the probe over a test circuit;
a superconducting quantum interference device (SQUID) attached to the probe and configured to be coupled to the test circuit such that an electronic noise present in the test circuit induces a first current that flows through the SQUID; and
a current path configured to receive a second current that flows through the SQUID, wherein the SQUID 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, and
a second voltage in response to the sum of the first current and the second current being greater than the threshold current.
2 . The diagnostic device of claim 1 , wherein the SQUID is configured to be inductively coupled to the test circuit.
3 . The diagnostic device of claim 1 , wherein the motor is configured to move the probe along a first axis and a second axis that are orthogonal to each other and parallel to the test circuit.
4 . The diagnostic device of claim 3 , wherein the motor is configured to move the probe along a third axis that is orthogonal to the first axis, the second axis, and the test circuit.
5 . The diagnostic device of claim 1 , wherein the first voltage is substantially equal to zero.
6 . The diagnostic device of claim 1 , wherein the first voltage is less than the second voltage.
7 . The diagnostic device of claim 1 , wherein the second voltage is greater than zero.
8 . The diagnostic device of claim 1 , wherein the test circuit comprises a complementary metal-oxide semiconductor (CMOS) circuit.
9 . The diagnostic device of claim 1 , wherein the probe comprises a scanning microscopy probe.
10 . The diagnostic device of claim 1 , wherein the SQUID comprises a superconducting loop, and wherein the SQUID is configured such that the first current flows around the superconducting loop.
11 . The diagnostic device of claim 10 , wherein the superconducting loop comprises a first Josephson junction and a second Josephson junction.
12 . The diagnostic device of claim 11 , wherein the superconducting loop further comprises a first superconducting material and a second superconducting material, and wherein the first superconducting material and the second superconducting material meet at the first Josephson junction and the second Josephson junction.
13 . The diagnostic device of claim 11 , wherein the threshold current is based on one or more of:
a length of the first Josephson junction and the second Josephson junction,
a width of the first Josephson junction and the second Josephson junction,
a shape of the first Josephson junction and the second Josephson junction,
a cross-sectional area of the first Josephson junction and the second Josephson junction,
a material that forms the first Josephson junction and the second Josephson junction, or
an operating temperature of the SQUID.
14 . The diagnostic device of claim 11 , wherein the current path comprises a superconducting material, and wherein the first Josephson junction and the second Josephson junction each comprise the superconducting material.
15 . The diagnostic device of claim 1 , further comprising:
a current source configured to provide the second current; and
a computing device configured to determine a magnitude of the second current at which the output of the SQUID transitions from the first voltage to the second voltage.
16 . The diagnostic device of claim 1 , further comprising:
a current source configured to increase a magnitude of the second current at a controlled rate; and
a computing device configured to determine a time at which the output of the SQUID transitions from the first voltage to the second voltage.
17 . A diagnostic apparatus comprising:
an array of superconducting quantum interference devices (SQUIDs) configured to be positioned over an array of test circuits, wherein each SQUID of the array of SQUIDs is configured to be coupled to a respective test circuit of the array of test circuits such that an electronic noise present in the respective test circuit induces a respective first current that flows through each SQUID; and
a current source configured to provide a second current that flows through each SQUID, wherein each SQUID is configured to generate a respective output in a form of:
a respective first voltage in response to a respective sum of the respective first current and the second current being less than a respective threshold current, and
a respective second voltage in response to the respective sum of the respective first current and the second current being greater than the respective threshold current.
18 . The diagnostic apparatus of claim 17 , further comprising:
a computing device configured to determine, for each SQUID of the array of SQUIDs, a respective magnitude of the second current at which the respective output of each SQUID transitions from the respective first voltage to the respective second voltage.
19 . The diagnostic apparatus of claim 17 , wherein the current source is configured to increase a magnitude of the second current at a controlled rate, the diagnostic apparatus further comprising:
a computing device configured to determine, for each SQUID of the array of SQUIDs, a respective time at which the respective output of each SQUID transitions from the respective first voltage to the respective second voltage.
20 . A diagnostic device comprising:
a superconducting quantum interference device (SQUID) configured to be coupled to a test circuit such that an electronic noise present in the test circuit induces a first current that flows through the SQUID; and
a current path configured to receive a second current that flows through the SQUID, wherein the SQUID 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, and
a second voltage in response to the sum of the first current and the second current being greater than the threshold current.