Abstract: In a battery power supply apparatus for low-noise measurement systems or ultra high-sensitivity sensor elements (ultra-sensitive light or microwave sensors, or SQUID, SIS/SNS or other Josephson effect devices, etc.), the power supply device that supplies power to the outside and the control device that controls the power supply device perform bidirectional communications by means of an optical communications circuit, and thus it is possible to prevent noise arising in the control device from reaching the power supply device. In addition, it is possible to prevent the introduction of noise from the optical communications circuit into the power supply device within a shield case. Accordingly, it is possible to control the operation of the power supply device enclosed within the shield case from the control device outside of the shield case without having external noise affecting the power supply device.

Abstract: In a battery power supply apparatus for low-noise measurement systems or ultra high-sensitivity sensor elements (ultra-sensitive light or microwave sensors, or SQUID, SIS/SNS or other Josephson effect devices, etc.), the power supply device that supplies power to the outside and the control device that controls the power supply device perform bidirectional communications by means of an optical communications circuit, and thus it is possible to prevent noise arising in the control device from reaching the power supply device. In addition, it is possible to prevent the introduction of noise from the optical communications circuit into the power supply device within a shield case. Accordingly, it is possible to control the operation of the power supply device enclosed within the shield case from the control device outside of the shield case without having external noise affecting the power supply device.

Abstract: The heterojunction magnetic field sensor is basically a heterojunction structure forming a two-dimensional electron gas layer having a high carrier mobility at the junction portion of at least two different kinds of semiconductor layers having a different band gap, respectively, and further, at least one semiconductor layer having a quantum well structure is provided adjacent to and in contact with the two dimensional electron gas layer, the energy level of the ground state subband thereof being higher than that of the two-dimensional electron gas layer. This heterojunction magnetic field sensor has a high sensitivity which is not saturated even under a high electric field and provides an enhanced output even under the high electric field.