Quantum Voltage Noise Source (image) National Institute of Standards and Technology (NIST) Share Print E-Mail Caption This quantum voltage noise source (QVNS) provides a fundamentally accurate voltage signal that can be compared to the voltage noise from electrons in a resistor. Measuring the voltage noise enabled researchers to determine the Boltzmann constant, which relates an energy of a system to its temperature. Credit Dan Schmidt/NIST Usage Restrictions OK to republish in editorial articles with credit. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.