A magnetic field measuring apparatus includes an A/D conversion unit, an integration unit, and a post-processing unit. The A/D conversion unit is configured to sample a signal at a predetermined sampling frequency and perform conversion into digital data, the signal being based on an output voltage from a superconducting quantum interference device configure to detect a magnetic field emanating from a living organism. The integration unit is configured to obtain a biological magnetic field signal based on a value obtained by integrating the digital data, the biological magnetic field signal indicating a magnetic field emanating from the living organism. The post-processing unit is configured to perform decimation processing on the biological magnetic field signal output from the integration unit.

One example includes a superconducting latch system. The system includes a first input stage configured to receive a first input pulse and a second input stage configured to receive a second input pulse. The system also includes a storage loop configured to switch from a first state to a second state in response to receiving the first input pulse, and to switch from the second state to the first state in response to the second input pulse. The first state corresponds to no flux in the storage loop and the second state corresponds to a flux in the storage loop. The system further includes an output stage configured to generate an output pulse in the second state of the storage loop.

A magnetic field measuring element includes a Superconducting QUantum Interference Device magnetic sensors, the first sensor disposed either on a second plane perpendicular to a first plane including a coil surface of the third sensor and which includes the center of the third sensor, or in the vicinity of the second plane, and a second sensor disposed either on a third plane perpendicular to the first plane and the second plane, or in the vicinity of the third plane. The center of the first sensor is present either on a straight line which passes through the center of the third sensor and is perpendicular to the first plane, or in the vicinity of said straight line, and the center of the second sensor is present in a position displaced from a line joining the center of the third sensor and the center of the first sensor.

A magnetic field measuring element includes a Superconducting QUantum Interference Device magnetic sensors, the first sensor disposed either on a second plane perpendicular to a first plane including a coil surface of the third sensor and which includes the center of the third sensor, or in the vicinity of the second plane, and a second sensor disposed either on a third plane perpendicular to the first plane and the second plane, or in the vicinity of the third plane. The center of the first sensor is present either on a straight line which passes through the center of the third sensor and is perpendicular to the first plane, or in the vicinity of said straight line, and the center of the second sensor is present in a position displaced from a line joining the center of the third sensor and the center of the first sensor.

A magnetic field measuring apparatus that includes a first board having a plurality of first connecting parts, at least one second board connected to the plurality of first connection parts, and a power supply unit supplying power to the first board and the at least one second board so as to measure a magnetic field includes at least one first voltage regulator disposed on the first board to generate a first voltage using power from the power supply unit; and at least one second voltage regulator disposed on any one of the at least one second board to generate a second voltage using the first voltage.

A magnetic field measuring apparatus includes a digital FLL circuit including ADC that converts a periodically changing voltage output from a SQUID according to a change in a magnetic field into a digital value, a digital integrator that integrates the digital value output from the ADC, a DAC that converts an integrated value output from the digital integrator into a voltage, a converter that converts the voltage output from the DAC into a current, and a coil that generates the magnetic field received by the SQUID, based on the current output from the converter. A calculating device calculates a digital value indicating a flux quantum based on the digital value output from the ADC when the ADC converts the periodically changing voltage output from the SQUID upon receiving the magnetic field generated by a current that is obtained by converting a voltage generated by a voltage generator.

A magnetic field measuring apparatus includes a digital FLL circuit. The digital FLL circuit includes a first amplifier configured to amplify voltage output by a superconducting quantum interference device in accordance with strength of a magnetic field strength, an AD converter configured to, convert analog signals to first digital values, an integrator configured to integrate the first digital values output by the AD converter, a DA converter configured to receive an integral value output by the integrator as a second digital value, convert the second digital value to voltage, and output the converted voltage, a signal switcher configured to connect an output of the first amplifier or an output of the DA converter to an input of the AD converter, and a storage unit configured to store a correction value that corrects the integral value received by the DA converter.

A circuit includes a Superconducting Quantum Interference Array (SQIF), a bias circuit, and a coil. The SQIF generates an output voltage that is a transfer function of the magnetic flux perpendicularly passing through the SQIF. An external magnetic field and a bias magnetic field supply the magnetic flux. The bias circuit generates a bias current for biasing the SQIF at an operating point. The coil generates the bias magnetic field through the SQIF from the bias current of the bias circuit. The bias magnetic field provides nullifying feedback to the SQIF that counterbalances a low-frequency portion of the external magnetic field, such that the output voltage of the SQIF detects a high-frequency portion of the external magnetic field. The circuit can be a receiver with the output voltage of the SQIF detecting an electromagnetic signal while the receiver is moving with changing orientation relative to the Earth's magnetic field.

A circuit includes a Superconducting Quantum Interference Array (SQIF), a bias circuit, and a coil. The SQIF generates an output voltage that is a transfer function of the magnetic flux perpendicularly passing through the SQIF. An external magnetic field and a bias magnetic field supply the magnetic flux. The bias circuit generates a bias current for biasing the SQIF at an operating point. The coil generates the bias magnetic field through the SQIF from the bias current of the bias circuit. The bias magnetic field provides nullifying feedback to the SQIF that counterbalances a low-frequency portion of the external magnetic field, such that the output voltage of the SQIF detects a high-frequency portion of the external magnetic field. The circuit can be a receiver with the output voltage of the SQIF detecting an electromagnetic signal while the receiver is moving with changing orientation relative to the Earth's magnetic field.

A superconducting quantum interference device (SQUID) for mobile applications comprising: a superconducting flux transformer having a pickup coil and an input coil, wherein the input coil is inductively coupled to a Josephson junction; a resistive element connected in series between the pickup coil and the input coil so as to function as a high pass filter such that direct current (DC) bias current is prevented from flowing through the input coil; and a flux bias circuit electrically connected in parallel to the superconducting flux transformer between the pickup coil and the input coil so as to reduce motion-induced noise.