Hyperfine interaction induced decoherence of electron spins in quantum dots

Abstract

We investigate in detail, using both analytical and numerical tools, the decoherence of electron spins in quantum dots ͑QDs͒ coupled to a bath of nuclear spins in magnetic fields or with various initial bath polarizations, focusing on the longitudinal relaxation in low and moderate field and polarization regimes. An increase of the initial polarization of nuclear-spin bath has the same effect on the decoherence process as an increase of the external magnetic field, namely, the decoherence dynamics changes from smooth decay to damped oscillations. This change can be observed experimentally for a single QD and for a double-QD setup.Our results indicate that substantial increase of the decoherence time requires very large bath polarizations, and the use of other methods ͑dynamical decoupling or control of the nuclear spins distribution͒ may be more practical for suppressing decoherence of QD-based qubits.

Universal quantum control of two-electron spin quantum bits using dynamic nuclear polarization

“…Here we take advantage of the interaction of 1 the electrons with the nuclear magnetic field of the Ga and As sublattices of the host material in order to generate the required magnetic field gradient. While fluctuations of this hyperfine field are known to be a major source of decoherence [8][9][10][11][12] , in this letter we demonstrate the possibility of building up a gradient in the hyperfine field that significantly exceeds the fluctuations and can be sustained for times longer than 30 min. This is done by employing pumping schemes that transfer spin and thus magnetic moment from the electronic system to the nuclei.…”

Quantum Effects in Higher-Order Correlators of a Quantum-Dot Spin Qubit

“…2(a) and (b), respectively, for timescales where t 1,2 are in the nanosecond range. Figure 2(a) shows that the amplitude of g 2 (t) oscillates with the Larmor 2 owing to contributions of randomly oriented Overhauser fields [20,[28][29][30]. The red line shows the application of Eq.…”

Long-term dynamics of the electron-nuclear spin system of a semiconductor quantum dot

“…35 We neglect the part of Eq. (9) proportional to the square of the mean electron spin. 36 This saturation value is determined by the fluctuation of the electron spin along Ω.…”