Optical Spin Noise of a Single Hole Spin Localized in an (InGa)As Quantum Dot

We advance spin noise spectroscopy to the ultimate limit of single spin detection. This technique enables the measurement of the spin dynamic of a single heavy hole localized in a flat (InGa)As quantum dot. Magnetic field and light intensity dependent studies reveal even at low magnetic fields a strong magnetic field dependence of the longitudinal heavy hole spin relaxation time with an extremely long $T_1$ of $\ge$ 180 $\mu$s at 31 mT and 5 K. The wavelength dependence of the spin noise power discloses for finite light intensities an inhomogeneous single quantum dot spin noise spectrum which is explained by charge fluctuations in the direct neighborhood of the quantum dot. The charge fluctuations are corroborated by the distinct intensity dependence of the effective spin relaxation rate

Integrated quantized electronics: a semiconductor quantized voltage source

The Josephson effect in superconductors links a quantized output voltage Vout = f \cdot(h/2e) to the natural constants of the electron's charge e, Planck's constant h, and to an excitation frequency f with important applications in electrical quantum metrology. Also semiconductors are routinely applied in electrical quantum metrology making use of the quantum Hall effect. However, despite their broad range of further applications e.g. in integrated circuits, quantized voltage generation by a semiconductor device has never been obtained. Here we report a semiconductor quantized voltage source generating quantized voltages Vout = f\cdot(h/e). It is based on an integrated quantized circuit of a single electron pump operated at pumping frequency f and a quantum Hall device monolithically integrated in series. The output voltages of several \muV are expected to be scalable by orders of magnitude using present technology. The device might open a new route towards the closure of the quantum metrological triangle. Furthermore it represents a universal electrical quantum reference allowing to generate quantized values of the three most relevant electrical units of voltage, current, and resistance based on fundamental constants using a single device.Comment: 15 pages, 3 figure