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An ultralow noise current amplifier based on superconducting quantum interference device for high sensitivity
C Granata1, A Vettoliere, M Russo
1Istituto di Cibernetica "E. Caianiello" del Consiglio Nazionale delle Ricerche, Pozzuoli, Napoli, Italy. c.granata@cib.na.cnr.it.
The Review of Scientific Instruments
|February 2, 2011
Summary
A novel niobium direct current superconducting quantum interference device (SQUID) current amplifier offers ultrahigh sensitivity. This advanced sensor achieves a record low current noise of 110 fA/√Hz, enabling precise measurements for applications like gravitational wave detection.
Area of Science:
- Physics
- Superconductivity
- Quantum Electronics
Background:
- Superconducting Quantum Interference Devices (SQUIDs) are sensitive magnetic flux detectors.
- Ultrahigh sensitive current amplifiers are crucial for various scientific applications.
- Existing SQUID-based amplifiers have limitations in sensitivity and noise performance.
Purpose of the Study:
- To develop an integrated ultrahigh sensitive current amplifier using a niobium DC SQUID.
- To achieve a significantly lower current noise level compared to existing SQUID amplifiers.
- To demonstrate the sensor's capability in noise thermometry applications.
Main Methods:
- Designed a sensor with a multiturn signal coil tightly coupled to a SQUID magnetometer's flux transformer.
- Fabricated the sensor using niobium material.
- Characterized the sensor's performance in liquid helium using low-noise readout electronics.
- Measured current noise levels and voltage-flux characteristics.
Main Results:
- Achieved a current sensitivity of 62 nA/Φ(0).
- Obtained a low current noise of 110 fA/√Hz at 4.2 K, a factor of two lower than comparable SQUIDs.
- Demonstrated stable and reliable operation with a smooth voltage-flux characteristic.
- Successfully applied the sensor for Nyquist noise measurements of integrated resistors.
Conclusions:
- The developed niobium DC SQUID current amplifier provides unprecedented sensitivity.
- Its low noise performance makes it suitable for demanding applications.
- Potential applications include gravitational wave detector readout and advanced noise thermometry.
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