Fast sensitive amplifier for two-probe conductance measurements in single molecule break junctions.

We demonstrate an amplifier based on the Wheatstone bridge designed specifically for use in single molecule break junctions. This amplifier exhibits superior performance due to its large bandwidth, flat frequency response, and high sensitivity. The amplifier is capable of measuring conductance values from 102 to 10-6G0 (G0 = 2e2/h), while maintaining a bandwidth in excess of 20 kHz, and shows remarkable resolution in the molecular conductance regime of 10-2 to 10-5 G0.