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Register a new userDetection and amplification of spin noise using scattered laser light in a quantum-dot microcavity
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Fundamental properties of the spin-noise signal formation in a quantum-dot microcavity are studied by measuring the angular characteristics of the scattered light intensity. A distributed Bragg reflector microcavity was used to enhance the light-matter interaction with an ensemble of n-doped (In,Ga)As/GaAs quantum dots, which allowed us to study subtle effects of the noise signal formation. Detecting the scattered light outside of the aperture of the transmitted light, we measured the basic electron spin properties, like g-factor and spin dephasing time. Further, we investigated the influence of the microcavity on the scattering distribution and possibilities of signal amplification by additional resonant excitation.
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We report on the first experimental observation of spin noise in a single semiconductor quantum well embedded into a microcavity. The great cavity-enhanced sensitivity to fluctuations of optical anisotropy has allowed us to measure the Kerr rotation and ellipticity noise spectra in the strong coupling regime. The spin noise spectra clearly show two resonant features: a conventional magneto-resonant component shifting towards higher frequencies with magnetic field and an unusual nonmagnetic component centered at zero frequency and getting suppressed with increasing magnetic field. We attribute the first of them to the Larmor precession of free electron spins, while the second one being presumably due to hyperfine electron-nuclei spin interactions.
We theoretically study the coupled modes of a medium-size quantum dot, which may confine a maximum of ten electron-hole pairs, and a single photonic mode of an optical microcavity. Ground-state and excitation energies, exciton-photon mixing in the wave functions and the emission of light from the microcavity are computed as functions of the pair-photon coupling strength, photon detuning, and polariton number.
We consider a double quantum dot in the Pauli blockade regime interacting with a nearby single spin. We show that under microwave irradiation the average electron occupations of the dots exhibit resonances that are sensitive to the state of the nearby spin. The system thus acts as a spin meter for the nearby spin. We investigate the conditions for a non-demolition read-out of the spin and find that the meter works at temperatures comparable to the dot charging energy and sensitivity is mainly limited by the intradot spin relaxation.
Mean-field evolution equations for the exciton and photon populations and polarizations (Bloch-Lamb equations) are written and numerically solved in order to describe the dynamics of electronic states in a quantum dot coupled to the photon field of a microcavity. The equations account for phase space filling effects and Coulomb interactions among carriers, and include also (in a phenomenological way) incoherent pumping of the quantum dot, photon losses through the microcavity mirrors, and electron-hole population decay due to spontaneous emission of the dot. When the dot may support more than one electron-hole pair, asymptotic oscillatory states, with periods between 0.5 and 1.5 ps, are found almost for any values of the system parameters.
Shot noise of quantum ring (QR) excitons in a p-i-n junction surrounded by a microcavity is investigated theoretically. Some radiative decay properties of a QR exciton in a microcavity can be obtained from the observation of the current noise, which also gives the extra information about one of the tunnel barriers. Different noise feature between the quantum dot (QD) and QR is pointed out, and may be observed in a suitably designed experiment.
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