Spin Lifetimes in Quantum Dots from Noise Measurements

We present a method of obtaining information about spin lifetimes in quantum dots from measurements of electrical transport. The dot is under resonant microwave irradiation and at temperatures comparable to or larger than the Zeeman energy. We find that the ratio of the spin coherence times T(1)/T(2) can be deduced from a measurement of current through the quantum dot as a function the applied magnetic field. We calculate the noise power spectrum of the dot current and show that a dip occurs at the Rabi frequency with a linewidth given by 1/T(1)+1/T(2).