Asymmetric Noise in Carbon Nanotube Quantum Dots

We report on low-temperature noise measurements of carbon nanotube quantum dots. The dots are asymmetric, having one ferromagnetic and one superconducting lead. Our measurements indicate that the noise is also asymmetric with respect to current, apparently depending on the direction of electron tunneling. Additionally, we observe that the gate voltage modulates the noise. We discuss these results relative to the standard model for quantum dots as well as spin blockade.